{"1": {"fulltext": "MACHINE DESIGN\\nPART I.\\nAmerican\\nSchool of Correspondence\\n(Chartered by the Commonwealth of Massachusetts\\nCopyright 1900\\nBY\\nAmerican School of Correspondence.\\nBOSTON, MASS.,\\nU. S. A.", "height": "4759", "width": "3316", "jp2-path": "machinedesign00amer_0001.jp2"}, "2": {"fulltext": "", "height": "4372", "width": "2816", "jp2-path": "machinedesign00amer_0002.jp2"}, "3": {"fulltext": "MACHINE DESIGN\\nPART I.\\nINSTRUCTION PAPER\\nAmerican\\nr\u00c2\u00bb\\nSchool of Correspondence\\n(Chartered, by the Commonwealth of Massachusetts.)\\nCopyright 1900\\nBY\\nAmerican School of Correspondence\\nBOSTON, MASS.,\\nU. S. A.", "height": "4659", "width": "3028", "jp2-path": "machinedesign00amer_0003.jp2"}, "4": {"fulltext": "TWO COPIES RECEIVED,\\nLibrary of CeBgpefi^\\nOffice o f tfc\u00c2\u00ab\\nAPR 2 61800\\n\u00e2\u0080\u00a2\u00e2\u0080\u009c\u00e2\u0096\u00a0sl tor of Copyrights,\\nTJ\u00c2\u00a350\\n,Asz\\nA\\nSECOND COPY,\\nffVZ-\\n00", "height": "4659", "width": "3028", "jp2-path": "machinedesign00amer_0004.jp2"}, "5": {"fulltext": "MACHINE DESIGN.\\nMachine design treats of the design and construction of\\nmachines and their various parts.\\nA machine is a combination of movable parts, arranged on a\\nsupporting frame, and placed between the source of power and the\\nwork.\\nThe object of a machine is to transform the energy supplied\\nat the point where the machine receives its motion, into work at\\nthe point where the resistance is overcome.\\nThe various parts may be arranged to change the direction or\\nvelocity of the power or to overcome great resistance with small\\nforce. For instance, a steam engine changes rectilinear to circular\\nmotion while a planer changes circular to rectilinear. A lathe\\nis a familiar example of the change in velocity. Hydraulic presses\\nand testing machines illustrate the overcoming of a great resistance\\nby a small force.\\nA machine cannot move of itself nor create power. According\\nto the law of the conservation of energy, no increase of power can\\nbe obtained from any machine. If a machine were frictionless,\\nthe product of the force exerted at the driving point and the\\nvelocity of the driving point would equal the product of the\\nresistance and the distance through which the resistance is over\u00c2\u00ac\\ncome in the same time.\\nThe operation of machines depends upon two conditions the\\ntransmission of certain forces and the production of definite result\u00c2\u00ac\\nant motions.\\nIn designing machinery both of these conditions must be con\u00c2\u00ac\\nsidered. The machine must be constructed so that each part will\\nbear the strains placed on it and also have the proper relative\\nmotions.", "height": "4659", "width": "3028", "jp2-path": "machinedesign00amer_0005.jp2"}, "6": {"fulltext": "4\\nMACHINE DESIGN.\\nThe nature of these relative movements is independent both\\nof the power transmitted and of the dimensions of the parts. We\\nsee that this is true for in the model of a machine, the dimensions\\nof the parts may vary considerably from those requisite for strength.\\nAt the same time, the relative motions of the parts of a model\\nwhich may be worked by hand, are the same as those of the larger\\nmachine which perhaps transmits 1000 H. P.\\nPure riechanism treats of the motion and form of parts of\\nmachines and the manner of supporting them.\\nConstructive Mechanism treats of the calculation of the\\nforces acting on these parts. It involves the selection of materials,\\nand the calculation of the dimensions for requisite strength and\\nstiffness.\\nA riechanism is a portion of a machine where two or more\\nparts are so arranged and connected that the motion of one com\u00c2\u00ac\\npels a definite motion of others.\\nMachines are made up of trains of mechanisms. The sewing\\nmachine, watch and printing press are examples.\\nnotion and rest are relative terms. If we consider some\\npoint or body as fixed, motion may be either relative or absolute.\\nFor this work the earth is assumed to be fixed and motion referred\\nto it absolute.\\nA point moving in space follows a line, either curved or straight\\nwhich is called its path.\\nDirection, like motion, is relative to continuous motion. If\\na point continues to move indefinitely in the same direction, it is\\nsaid to have continuous motion. In this case, the path must be a\\nclosed curve. A shaft turning on its bearings or the crank-pin of\\nan engine, is an example of this motion.\\nIntermittent notion. When a part of a machine has motion\\nin alternate directions and definite periods of rest, it has intermit\u00c2\u00ac\\ntent motion.\\nReciprocating Motion, If a point travels in the same path,\\nalternately in opposite directions, its motion is said to be recipro\u00c2\u00ac\\ncating. If the motion is reciprocating and also ciroular, it is called\\nvibration.\\nVelocity. The ratio of space to the time is called linear vel\u00c2\u00ac\\nocity, if the path of the moving body is a straight line. If the", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0006.jp2"}, "7": {"fulltext": "MACHINE DESIGN.\\n5\\npath of the body is a curve the ratio of space to time is called\\nangular velocity.\\nVelocity may be uniform or variable according as the spaces\\ntraversed in equal times are equal or unequal.\\nVelocity -P a _ e\\nTime\\nSpace Time X Velocity.\\nThe unit of space is usually one foot; the unit of time, one\\nsecond. Hence velocity is expressed in feet per second.\\nAngular velocity is measured by the number of units of\\nangular space passed over in a unit of time. Angular space is\\nmeasured by circular measure of the ratio of the arc to the radius.\\nThe unit angle is the angle subtended by an arc equal in length to\\nthe radius. Angular velocity may be expressed in number of\\nrevolutions in a unit of time; one revolution is represented by 2 7 r\\nin circular measure.\\nLinear velocity\\nAngular velocity\\nLinear velocity\\nRadius\\nAngular velocity X Radius.\\nSuppose we wish to find the linear velocity of some point on\\nthe periphery of a fly-wheel. Evidently the point will travel,\\nduring one revolution, a distance equal to the circumference\\nof a circle of the given radius. The circumference is, from\\ngeometry, tt d or 2 it r. Let n be the number of revolutions per\\nminute, then the linear velocity is 2 it r n.\\nA fly-wheel is 20 feet in diameter and revolves at the rate of\\n50 revolutions per minute. Find the linear velocity of a point on\\nthe periphery.\\nLinear velocity 2 tt r n 2 X 3.1416 X 10 X 50\\n3141.6 feet per minute.\\nHow far from the centre of this wheel must a point be tr\\nhave a velocity of 20 feet per second\\ny\\nV 2 7r r n, or r\\n2 7 rn\\nThen, r\\n1200\\n2 X 3.1416 X 50\\n3.82 feet. Ans.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0007.jp2"}, "8": {"fulltext": "6\\nMACHINE DESIGN.\\nEXAMPLES FOR PRACTICE.\\n1. A wheel 3 feet in diameter makes 25 revolutions per\\nminute. What is the linear velocity of a point on the circumfer\u00c2\u00ac\\nence Ans. 235.62 feet per minute\\n2. A wheel makes 300 revolutions per minute. How far\\nfrom the center must a point be to have a linear velocity of 2827.44\\nfeet per minute Ans. IT feet.\\n3. Find the linear velocity of a fly-wheel when the angular\\nvelocity is 188.5 revolutions per minute, the wheel being 10 feet\\nin diameter. Ans. 942.5 feet per minute.\\nRevolution. A point revolves about an axis when it describes\\na circle the center of which lies within, and its plane of rotation is\\nperpendicular to, the axis. If the axis passes through the body,\\nas in the case of a wheel, the motion is called both rotation and\\nrevolution.\\nA body, like the earth for instance, may rotate about its own\\naxis and also revolve in an orbit about another axis.\\nCycle of JTotions- In case the parts of a mechanism go\\nthrough a series of motions which are repeated, each time the\\norder of the motion of the several parts being the same, the series\\nis called a cycle of motions. In the steam engine every revolu\u00c2\u00ac\\ntion is a cycle because each series of motions is repeated for every\\nrevolution. Two revolutions of the crank are necessary for one\\ncycle in some types of the gas engine.\\nThe part or piece of mechanism which causes motion, or to\\nwhich the power is applied is called the driver and the part whose\\nmotion is caused by the movement of the driver is the driven or\\nfollower.\\nFrame. The structure which supports or holds in position\\nthe moving parts and regulates the path of motion is called the\\nframe. The motions are often referred to the frame, as it is\\nusually fixed, that is, without motion. An exception to this is the\\nlocomotive frame.\\nTransmission. One object cannot move another unless the\\ntwo are in contact or are connected by some body that is capable\\nof communicating motion from one to the other. The above state-", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0008.jp2"}, "9": {"fulltext": "MACHINE DESIGN.\\n7\\nment does not take into account the action of natural forces, such\\nas gravity, magnetism, etc.\\nMotion transmitted by contact is seen in friction gearing, gear\\nwheels, etc. Belts, rope gearing, levers, links, etc., are examples\\nof motion by intermediate connection. Connectors are either rigid\\nor flexible.\\nnotion. Mechanism may be used to change the motion of\\nthe follower from that of the driver. It may differ in direction,,\\nkind, or velocity.\\nWork is the overcoming of resistance through distance. It\\nis the product of the resistance and the space through which it is-\\novercome. If a body is lifted from the earth, against the attrac\u00c2\u00ac\\ntion of gravity, the resistance is the weight of the body and the\\ndistance is the height to which the body is raised*. The work\\ndone is equal to the weight of the body multiplied by the distance.\\nThe Unit of Work is the foot-pound, that is, the amount of\\nwork done in lifting one pound through one foot. If F equals\\nthe force or weight and S equals the space or distance through\\nwhich F is moved, then work F X S. S velocity multi\u00c2\u00ac\\nplied by time V X T. Then if we raise 5 pounds to a height\\nof 20 feet we do 5 X 20 100 foot-pounds of work.\\nEnergy is the capacity for doing work. There are two kinds?\\nof energy, potential and kinetic.\\nPotential Energy is energy of position; water stored in a\\nreservoir for example. The water is capable of doing work by\\nmeans of a water wheel. Potential energy is measured in foot\u00c2\u00ac\\npounds, that is, it is the weight of the body multiplied by the dis\u00c2\u00ac\\ntance through which it is capable of acting.\\nPotential energy may also exist as stored heat or chemical\\nenergy, as in fuel, gunpowder or electric energy.\\nKinetic or Actual Energy is the energy of a moving body..\\nThe energy in a moving body is the work which it is capable of:\\nperforming against a resistance before it is brought to rest. It is-\\nequal to the work required to bring it from rest to its actual\\nvelocity. Kinetic energy is measured as the product of the weight\\nof the body and the height through which it must fall to acquire\\nthe actual velocity. From the laws of falling bodies this height", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0009.jp2"}, "10": {"fulltext": "8\\nMACHINE DESIGN.\\nequals the square of the velocity divided by twice the value of\\nthe earth\u00e2\u0080\u0099s attraction. Then\\nA\\nand energy.\\nE wh\\n2 g\\nThe weight of a body divided by g is called the mass, i. e\\nm\\nw\\nV\\nthen substituting m for in the equation\\n9\\n1 W V i I t\\nE it becomes E\\n*9\\nmv 2\\nEnergy is the capacity of doing work. The units of work\\nand energy are the same; then\\nF S ivh\\nmv 2\\nPower is the rate of performing work. It is equal to the\\nwork done divided by the time and is expressed as foot-pounds per\\nminute or per second. Thus horse-power is a measure of power,\\nbeing equal to 33,000 foot-pounds per minute or 550 foot-pounds\\nper second.\\nPower\\nFS\\nMATERIALS,\\nThe principal materials used in the construction of machinery\\nare cast and wrought iron, copper, wood, brass and other alloys.\\nThe properties and processes of manufacture for iron and steel\\nhave been described in Metallurgy.\\nCAST IRON.\\nCast iron is used to a considerable extent in the construction\\nof machines. For the heavy massive parts, the frames of lathes,\\nsteam-engines, planers, etc., for example, it is the best, material.\\nIt is not suitable for parts requiring strength, elasticity or those", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0010.jp2"}, "11": {"fulltext": "MACHINE DESIGN.\\n9\\nsubjected to shocks. For this reason piston-rods, connecting-rods,\\nshafts, etc., are usually made of steel or wrought iron.\\nMany complicated shapes that cannot be forged are readily\\ncast. The ease with which parts may be given the desired shape\\nmakes cast iron valuable.\\nCast iron contains 3 to per cent, of carbon with a little\\nsilicon. The hard and white varieties are used in the manufac\u00c2\u00ac\\nture of wrought iron. The gray irons are used in the foundry.\\nCast iron is made into the desired forms by melting it in a\\ncupola and pouring into moulds. The moulds are made in sand\\nor loam from patterns of pine wood. Patterns are made a little\\nlarger than the required casting because iron in solidifying con\u00c2\u00ac\\ntracts about i inch per foot in each direction. This contraction\\nis called shrinkage. In making a pattern a shrinkage rule is used\\nwhich is about inch longer per foot than the standard.\\nCastings are likely to be put into a state of internal stress\\nbecause of contraction when cooling. If some parts of the casting\\ncontract more than others, the casting may become twisted. Thin\\nparts of the castings solidify first. The contraction of the fluid\\nparts strains the portions already set and their resistance to\\ndeformation causes stresses to be set up in the parts which are\\nsolidifying.\\nFor example, the form shown in Fig. 1 has a rigid flange\\nFig. l. Fig. 2.\\nsurrounding the inner part. If the contraction of the cross piece\\ntakes place more slowly than the rim, it is likely to fracture. In\\na thick cylinder, as shown in section in Fig. 2, the outer portions\\nsolidify and begin the contraction. The contraction of the inner\\ninduces pressure in the outer portion, which being rigid causes a\\nresistance to contraction of the inner layers and puts them in ten-", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0011.jp2"}, "12": {"fulltext": "10\\nMACHINE DESIGN.\\nsion. A cylinder so constructed is not strong to resist bursting\\npressure. If the cylinder is cast while water circulates through\\nthe core, the reverse distribution of initial strains is set up. This\\ninsures a stronger cylinder because the inner layers are in a state\\nof compression and the outer portions are in tension.\\nThe arms of pulleys may be broken by tension if the rim is\\nthin and rigid. If the arms set first the rim may break near\\nthem. To have successful castings, the designer must carefully\\nconsider the dimensions of the various parts.\\nOn account of these initial strains, that cannot be calculated,\\ncast iron is unreliable. Cast iron structures usually have exces\u00c2\u00ac\\nsive dimensions to insure safety.\\nIn cooling, the crystals of cast iron arrange themselves per\u00c2\u00ac\\npendicularly to the surfaces from which heat radiates. For\\nthis reason all corners should be well rounded as shown in\\nFig. 3, so that the arrangement of the crystals will make the\\ncastings strong.\\nChilled Castings. If castings are cooled rapidly during\\nsolidification, the graphite is prevented from separating from the\\niron. This causes the iron to become harder. In order to chill\\nthe cast iron, the mould is made of or lined with this same mate\u00c2\u00ac\\nrial. The mould which is lined with loam for protection, is a\\ngood conductor of heat and the molten cast iron is cooled or chilled\\nduring solidification.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0012.jp2"}, "13": {"fulltext": "MACHINE DESIGN.\\n11\\nThe chilling usually extends to a depth of to of an inch\\nfrom the surface the interior remaining soft.\\nMalleable Cast Iron. Malleable cast iron is made by sur\u00c2\u00ac\\nrounding castings with oxide of iron, powdered red hematite or\\nperoxide of manganese; keeping them at a high temperature for\\na considerable time according to the size of the casting. The\\nelimination of carbon converts the cast iron into a crude form of\\nwrought iron. Malleable castings will stand blows better than\\nordinary castings.\\nCast iron is stronger than wrought iron when under press\u00c2\u00ac\\nure but it is much weaker under tension and impact.\\nWROUGHT IRON.\\nWrought iron is made from cast iron by eliminating part of\\nthe carbon. It is strong and tough and can easily be welded.\\nFor these reasons it is used for parts of machines and structures\\nrequiring strength and of simple form. Wrought iron parts are\\nshaped by forging and finished in the machine shop; steam ham\u00c2\u00ac\\nmers being used on the heavy portions.\\nWrought iron is rolled into plates, round and square bars,\\nangle, tee, channel, I beam sections, etc. Large wrought iron\\nstructures are built up of bars or plates riveted or bolted together.\\nWrought iron that has been rolled when cold has a greater\\ntensile strength than before rolling; but its ductility and tough\u00c2\u00ac\\nness is reduced. Annealing, or heating the iron to a red heat and\\nallowing it to cool slowly, restores it to the original condition.\\nCompression of iron when cold increases its strength but\\nreduces its ductility and toughness; annealing reduces strength\\nand increases toughness and ductility. If the iron is rolled or\\nhammered when hot, compression and annealing are carried on at\\nthe same time.\\nWrought iron is used for piston-rods, shafts, connecting-rods,\\nbolts, nuts, chains, etc.\\nSTEEL.\\nSteel is far the most useful material used in machine design.\\nIts properties depend upon the percentage of combined carbon,\\nsilicon, manganese, phosphorus, etc. Steel contains from .15 to\\n1.5 per cent, of carbon.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0013.jp2"}, "14": {"fulltext": "12\\nMACHINE DESIGN.\\nFormerly it was difficult to get sound castings, but by the use\\nof silicon, aluminum and other elements and prolonged annealing,\\nthe internal stresses are destroyed.\\nSteel can be welded, but greater care is necessary than in the\\nwelding of wrought iron.\\nTempering greatly increases the usefulness of steel, since it\\nbecomes hard if heated and cooled suddenly. With good steel\\nalmost any desired hardness may be obtained. The steel is heated\\nto the temperature indicated by the color of the oxide which forms\\nr.tits surface and is then quenched in oil or water. Hardness\\nmakes it suitable for cutting tools. When tempered it is hard,\\nstrong, has high elastic limit and little ductility.\\nCOPPER.\\nCopper is a reddish metal of great ductility and malleability.\\nIt is usually rolled or hammered into shape because it doesn\u00e2\u0080\u0099t cast\\nwell. Copper can be welded, but as it requires considerable care\\nto make a good joint, pieces are more often joined by brazing. It\\ncan be drawn into wire. The tensile strength of cast copper is\\nabout 20,000 pounds per square inch; of forged copper about 30,000\\npounds per square inch.\\nHammering, rolling and wire-drawing increases the tensile\\nstrength, but makes it hard and brittle. It can be made soft and\\ntough by annealing. It is expensive and is used for wire, fittings\\nand tubing. Its strength is less than that of wrought iron and\\ndecreases rapidly with rise of temperature.\\nALUniNUM.\\nAluminum is a soft, ductile, malleable metal of bluish white\\ncolor. It is very\u00e2\u0080\u0098light; next to magnesium the lightest of the\\nuseful metals. Its strength is about one-third that of wrought\\niron. Aluminum casts well, the shrinkage being about the same\\nas brass. The readiness with which aluminum unites with other\\nmetals makes it valuable for alloys. It can be electrically welded\\nbut doesn\u00e2\u0080\u0099t solder well.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0014.jp2"}, "15": {"fulltext": "MACHINE DESIGN.\\n13\\nBRONZE.\\nBronze, or gun-metal, is an alloy of copper and tin about 90\\nparts copper and 10 parts tin. It makes good castings. Bronze\\nis harder and less malleable than copper. Copper-tin alloys are\\nused for bearings because it is softer and wears faster than wrought\\niron or steel shafts.\\nThe hardness of bronze depends upon the proportion of tin\\nto increase hardness increase the amount of tin. An alloy of 92\\nparts copper and 3 parts tin is a soft bronze used for gear wheels.\\nPhosphor-bronze is made by mixing 2 or 3 per cent, of phos\u00c2\u00ac\\nphorus with ordinary bronze. Soft phosphor-bronze has a tensile\\nstrength of about 45,000 pounds per square inch; harder varieties\\nhave about 65,000 pounds and hard unarinealed wire has about\\n150,000 pounds. It is used for pump-rods, propellor-blades, etc.\\nManganese bronze, called white bronze, is an alloy of ordinary\\nbronze and ferro-manganese. Like phosphor-bronze it is used in\\nmarine work, because it resists the corroding action of sea-water.\\nManganese bronze is equal in tensile strength and toughness to\\nmild steel and can be easily forged.\\nBRASS.\\nThe alloy of copper and zinc is called brass sometimes tin\\nand a little lead are added. For bearings it has about 60 per cent,\\ncopper, 10 per cent, zinc and 30 per cent, tin and lead. Naval\\nbrass has 62 per cent, copper, 1 per cent, tin and 37 per cent. zinc.\\nRed brass consists of about 37 per cent, copper and for the rest\\nabout equal parts of tin, zinc and lead. Brass is used for bear\u00c2\u00ac\\nings, wire, fittings and ornamental work. Its tensile strength is-\\nabout 23,000 pounds per square inch.\\nFUSIBLE ALLOYS.\\nFusible alloys are made of tin, lead and bismuth. The melt\u00c2\u00ac\\ning point varies with the percentages of the various constituents.\\nIf made of 2 parts lead and 1 part tin, it melts at 475\u00c2\u00b0 F.; if 1\\npart lead, 1 part tin and 4 parts bismuth, the melting point is\\nabout 200\u00c2\u00b0 F. An alloy of 1 part cadmium, 4 parts bismuth, 1\\npart tin and 2 parts lead melts at 165\u00c2\u00b0 F.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0015.jp2"}, "16": {"fulltext": "14\\nMACHINE DESIGN.\\nBEARING ALLOYS.\\nThe principal constituents of bearing alloys are copper, tin,\\nlead, zinc, antimony and aluminum. The bronzes contain a\\nlarge per cent, of copper. A good bearing alloy is made of cop\u00c2\u00ac\\nper, 77 parts by weight, tin 3 parts and lead 15 parts.\\nBabbit metals have various proportions hard babbit haviijg\\nabout 89 per cent, tin, 4 per cent, copper and 7 per cent, antimony.\\nThere are many other alloys containing the metals in varying\\nproportions according to the intended use.\\nWOOD.\\nWood is but little used in machine construction. Soft woods\\nlike pine are used for patterns; hard varieties, oak and lignum-vitae\\nfor examples, are used for bearings. Sometimes levers are made\\nof wood and the pulleys of some lathes are constructed of the same\\nmaterial. The cogs of mortise wheels are often made of beech or\\nhorn-beam.\\nSHOP PROCESSES.\\nIn designing machinery it is necessary that the parts may be\\neasily made. A finely finished pattern is of no value if it cannot\\nbe taken from the mould. Complicated castings and forgings\\nshould be used only when absolutely necessary. Simple designs\\nare usually the best.\\nFor casting, patterns or models are made from wood in the\\npattern shop. The pattern maker has to consider and make allow\u00c2\u00ac\\nance for shrinkage in casting, for turning, boring and finishing.\\nHe arranges the patterns in such manner that the moulding, cast\u00c2\u00ac\\ning and finishing may be most cheaply done. Some parts can be\\nmoulded only by the use of cores. Parts to be finished by cutting\\ntools must be so placed that they will not be unsound by reason of\\nblow T holes. The founder follows the specifications of the draw\u00c2\u00ac\\nings mixing the pig iron in different proportions so as to get the\\nrequired strength and softness.\\nForging is the operation of shaping wrought iron or steel\\nwithout melting. These materials become plastic without fusing.\\nThe pieces are hammered or rolled into shape. If the work fo", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0016.jp2"}, "17": {"fulltext": "MACHINE DESIGN.\\n15\\nlight the smithing is done by hand; but when large forgings are\\nmade, steam hammers are used. When the pieces are very large,\\ngreat skill is required to arrange the operation so that the result\\nshall be a homogeneous sound piece.\\nFitting, finishing, boring and turning are the operations of\\ncutting the rough products of the foundry and forge to accurate\\ndimensions. Fitting, boring and turning are done by steel cutting\\ntools which shape the metal when cold. Cutting operations in\u00c2\u00ac\\nclude chipping and filling, drilling, turning, planing, shaping and\\nmilling.\\nConical surfaces, screws and nuts can be made in the lathe.\\nSTRAINS IN HACHINES.\\nThere are forces acting on the several parts of a machine\\nwhich will cause them to give way if they are not sufficiently\\nstrong. Among these forces are the following\\n1. The useful load caused by the power transmitted from\\nthe point of receiving the energy to the point where the useful\\nwork is accomplished.\\n2. Resistance due to friction in the machine.\\n3. Forces due to inertia caused by change of velocity of the\\nmoving parts.\\n4. Weight of parts of machines.\\n5. Centrifugal forces caused by changes in direction of\\nmotion.\\nThe total action caused by the above forces is called the\\nstraining action on whatever part is considered. This straining\\naction varies with the changes of working load, with the variation\\nof position of the parts, with the change in speed, etc. In design\u00c2\u00ac\\ning the various parts it is necessary to consider under what con\u00c2\u00ac\\nditions the straining actions are greatest and calculate the dimen\u00c2\u00ac\\nsions of those parts to safely stand that action.\\nIt is obvious that the maximum working load must be less\\nthan the breaking load. In most cases it should be very much\\nless. Generally it is much easier to determine (by means of test\u00c2\u00ac\\ning machines) the breaking strength than it is the working stress.\\nIn order to be sure of sufficient strength, it is customary to divide\\nthe breaking strength by the factor of safety, to find the allowable", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0017.jp2"}, "18": {"fulltext": "16\\nMACHINE DESIGN.\\nworking load. Results from actual cases provide us witli average\\nfactors of safety for various conditions. In case the straining\\nactions are well known and the stresses are steady, the factors are\\nsmall. A large factor is necessary when the straining actions are\\nlikely to be greatly in excess of the calculations, when the material\\nis not reliable and when the parts are liable to shock. Some\\ndesigners never use the term factor of safety, but know from\\nexperience that the various materials will safely carry a certain\\nload under given conditions.\\nIn most cases a permanent set would be injurious; it might\\nprevent the movements of some parts of a machine. Under these\\nconditions it is evident that the working stress must be less than\\nthe elastic limit.\\nriACHINE DRAWINGS.\\nMachines are designed from principles obtained by successful\\npractice and from mathematical calculations. In order that both\\nthe designer and the mechanic may have a clear idea of the work,\\nthe designer makes a drawing of the machine. The drawing\\nindicates the size and shape of the various parts and how they are\\nto be put together. By means of the drawing, the designer calcu\u00c2\u00ac\\nlates the relative motions of the parts and arranges them so that\\nthey will not interfere with each other. He calculates the sizes\\nfor strength and considers the modifications which will produce\\nthe greatest efficiency, or least cost of manufacture. The drawing\\nindicates how the work is to be performed and distributed in the\\ndifferent shops. All dimensions, names of materials and finish\\nmarks should be clearly shown so that the workman, by carrying\\nout accurately the ideas of the designer, may produce the desired\\nmachine.\\nUsually several views of the part to be made are shown.\\nSometimes it is necessary to show sections in order that the inter\u00c2\u00ac\\nnal construction or sectional shape may be easily understood.\\nThese sections are usually drawn through the axis, or center, but\\nit is sometimes advisable to show sections of other portions.\\nWhere the drawing shows a section, the portions of metal or wood\\nsupposed to be cut are covered with parallel lines at equal dis\u00c2\u00ac\\ntances and usually oblique. These sections are called hatched\\ncross hatched, or simply sectioned. The character of the li nes", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0018.jp2"}, "19": {"fulltext": "MACHINE DESIGN.\\nIT\\nfull lines? dotted, broken, light or heavy, indicate the material sup\u00c2\u00ac\\nposed to be cut. One kind indicates cast iron, another steel,\\nanother brass, etc. There is no standard for cross hatching, differ\u00c2\u00ac\\nent draughtsmen using lines of various character. There is likely\\nto be a confusion unless the parts have the name of the material\\nprinted on or near it, or a key is provided.\\nFig. 4 shows the lines as generally used; those representing\\nSTEEL\\nBRASS\\nCOPPER\\nLEAD OR\\nBABBITT\\nWOOD\\nCAST IRON\\nCOMBINED\\nFh\\n4\\ncast iron, brass, wood and lead being almost universal, the others\\nare subject to more change. The lines may run from left to right,\\nor right to left; in case two or more parts of the same metal are-\\nbrought together it is necessary to avoid confusion by varying the\\ndirection and angles of the lines. If the hatching were to be the\\nsame, the parting line would be confused and one might think it\\nall one piece.\\nWhen drawing designs of the details, it is well to make them\\nas large as is convenient. The scales in general use are full size;\\nhalf size, 3 inches or 1J inches 1 foot. A drawing is never\\nmade 1 size or by such scales as 2 inches or 1 inch 1 foot.\\nA working drawing is one that shows all the dimensions of\\nan object in such manner that the object may be made by refer\u00c2\u00ac\\nence to the drawing. It is a practical application of the study of\\nprojections. Usually three views are sufficient, elevation, plan or\\nhorizontal projection and end view. Besides these views, sections\\nto show the interior construction are added.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0019.jp2"}, "20": {"fulltext": "18\\nMACHINE DESIGN.\\nIt is not sufficient to draw the various views and sections the\\ncorrect size; the dimensions also should be placed on the draw\u00c2\u00ac\\ning. The workman can tell immediately the size of any given\\npart without scaling it from the drawing. Although desirable, it\\nis not necessary that a drawing be made accurately, provided all\\nthe dimensions are put in correctly. The chances of error are\\ngreatly reduced by removing the necessity to scale off dimensions.\\nDimensions should be used systematically and wherever nec\u00c2\u00ac\\nessary. In placing dimensions on drawings, a line should be\\ndrawn from one point to the other. The number representing the\\ndimension is placed in the space left for it at the centre of the\\nline. These lines should be either fine full lines or dashes about\\ninch long. Arrow heads are placed on the ends of the line,\\nthe heads or vertex of the arrow just touching the points or\\nlines. In case the dimensions are very small, the arrow heads may\\nbe outside instead of between the lines, or pointing toward each\\nother. The dimensions should be written in feet, inches, halves,\\nquarters, eighths, sixteenths, etc. of inches. Fractions should be\\nreduced to lowest terms. Write not T 6 g, nor r fhe dividing\\nline of the fraction should be parallel to the direction of the\\ndimension line never an oblique line because the oblique line\\nmay be mistaken for some part of a number. Feet are repre\u00c2\u00ac\\nsented by the symbol inches by The inch marks should be\\nplaced after the fraction not between the whole number and the\\nfraction; thus, eight feet, seven and three quarters inches should\\nbe written 8 7f not 8 7 When the length is even feet it\\nis usual to write it 8 0 in order that the workman may know\\nthat the inches were not left off by mistake.\\nIt is necessary to get in all the important dimensions, espe\u00c2\u00ac\\ncially the over-all dimensions, so that the workman will not be\\ncompelled to add up several small dimensions in order to select\\nhis stock.\\nDimensions are often placed between two views and usually\\noutside the several views. When placed outside, extension lines\\nare used, that is, a fine or dash line is drawn as a continuation of\\nlines or edges.\\nIn placing the dimensions of a circle, give the diameter, not\\nthe radius. When an arc is used, give the radius. Holes mav be", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0020.jp2"}, "21": {"fulltext": "MACHINE DESIGN.\\n19\\nlocated by giving the dimensions from the outside, or from the\\ncenter of figure, to the center of the hole. The distance from\\ncenter to center shows their distance apart. In case the holes are\\narranged in a circle, as in a cylinder head for instance, give the\\ndiameter of the circle whose circumference passes through the\\ncenter of the holes.\\nIn making sectional views the plane of the section passes\\nthrough the center line of a shaft, bolt, screw, or cylinder, and\\nthe cylinder part is not represented in section but in full.\\nSometimes, in addition to the above views an isometric or\\noblique projection is made. In the isometric projection only one\\nview is used. The object is placed in such a position that its lines\\nor edges are parallel to three rectangular axes. The dimensions\\nare measured accurately on these lines, or lines parallel to them,\\nand the lengths are true, not foreshortened, as in perspective\\ndrawing. Lines which represent length and breadth make angles\\nof 30\u00c2\u00b0 with the horizontal and those representing thickness are\\nvertical lines.\\nOblique projections are similar to isometric projections except\\nthat the lines which make angles of 30\u00c2\u00b0 with the horizontal in the\\nisometric projection make angles of 45\u00c2\u00b0 in the oblique.\\nIt is usual when making mechanical or working drawings to\\ndo the work in pencil first, and then ink in the necessary lines, or\\na piece of tracing cloth is placed over the pencil drawing and the\\nlines which show through are then inked. The latter method is\\nused in case a number of blue prints are desired for the shops or\\noffice.\\nIn the pencil work, accuracy is necessary. Some beginners\\nthink they can correct inaccuracies in pencil by care in inking.\\nThe lines should be located exactly of the required length. A\\nhard pencil; 4 H or 6 H is generally used. A hard pencil, when\\nsharp, makes a depression in the paper which cannot be erased.\\nFor this reason press lightly on the pencil.\\nIn inking, it is better to make circles, arcs of circles and\\ncurved lines first It is much easier to make straight lines meet\\narcs, or to make them tangent to circles or arcs, than the reverse.\\nTo indicate an edge or intersection of two planes a full line\\n_is used; edges of intersections which are concealed are", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0021.jp2"}, "22": {"fulltext": "20\\nMACHINE DESIGN.\\nrepresented by dotted lines. Dot and dash lines*\\n_. _ ._._. or_. _. ._ ._. indicate center lines\\nor axes. A fine line or a series of long dashes-\\n-is used for dimension lines. Titles, various views, sections,\\nnames of materials, etc., are lettered on the drawings. The styles\\nand the care taken in this work varies with the draughtsman or\\nwith the amount of time at his disposal. In every case all let\u00c2\u00ac\\ntering should be neatly done and of some clear cut simple form.\\nMarks indicating in which shop the work is to be done and for\\nclassification are also placed on drawings. Fig. 5 shows a work\u00c2\u00ac\\ning drawing of a three inch pillow block which illustrates the\\nabove principles. The three views side, plan and end are half in\\nsection.\\nDESIGN.\\nParts of machines are designed from rules derived from\\nStrength of Materials,\u00e2\u0080\u009d other rules are based on the wear of the\\nparts, while others depend on the size or thickness necessary for\\nstiffness or a sound casting. In case theory doesn\u00e2\u0080\u0099t accord with\\nthe practice of successful designers, it is safe to follow the latter.\\nSome parts of machines, bolts, nuts, screws, pipes, etc., can\\nbe obtained in standard sizes from various factories. The designer\\nshould know these standard sizes and make his details of such\\nshapes that they will conform. The designer must also keep in\\nmind the processes and tools to be used so that the construction\\nwill not be too difficult or expensive.\\nUsually dimensions are expressed in feet and inches and such\\nfractions of inches as i, Ag, A^. i, i, i or Ag are never used\\nsince the scales in shops are not divided in these fractions.\\nDecimals are used only for great accuracy or in the design of gear\\nteeth.\\nAll machines are made up of different combinations of simple\\nprinciples. The designer must know these principles and the rela\u00c2\u00ac\\ntions they bear to one another. He must also have a thorough\\nknowledge of the machine the work it is to do; the character of\\npower to be applied and in some cases the location and surround\u00c2\u00ac\\nings. A study of machines that have been designed to do similar\\nwork will be of great assistance. A wide knowledge of machines", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0022.jp2"}, "23": {"fulltext": "MACHINE DESIGN.\\n21", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0023.jp2"}, "24": {"fulltext": "22\\nMACHINE DESIGN.\\npermits the designer to have many ideas of details for the new\\nmachine.\\nOften several complete drawings are necessary before the final\\nresult is attained. An idea that seems desirable may not prove so\\nwhen the details are worked out. Sometimes the relative motions\\nare all right, but when the parts are designed for strength, they\\nare found to interfere with each other. The expense of construc\u00c2\u00ac\\ntion or the difficulties of manufacture may render a good design\\nimpracticable.\\nAll notes, calculations and sketches of details and combina\u00c2\u00ac\\ntions should be carefully preserved for reference. Ideas worthless\\nfor some particular machine may be found very valuable for an\u00c2\u00ac\\nother. It is well to keep sketches, calculations and memoranda in\\nbooks rather than on loose sheets of paper that may become lost\\nor misplaced.\\nThe estimates for weights and cost of machinery are made\\nfrom drawings. The volume is found by mensuration and when\\nmultiplied by the weight of a cubic unit of the material gives the\\nweight. Considerable skill and experience is sometimes necessary\\nto estimate the volumes of irregular shaped parts. If the weights\\nare known the cost is estimated from market values. The time\\nnecessary for completion is also judged from the amount of work\\nand the ease with which it can be accomplished.\\nAt the beginning an inexperienced designer is usually taught\\nby making drawings of details which have been designed by others.\\nOften he is employed for some time simp\u00e2\u0080\u0099y tracing drawings.\\nAfter a little he is given the principal dimensions of the simpler\\nparts and instructed to make working drawings for the pattern,\\nforge or machine shops. During this time he becomes familiar\\nwith methods adopted in shops, standard dimensions, allowable\\nstresses for the various materials, methods of adjusting wear and\\nlubrication, necessary dimensions for sound castings, etc.\\nThe following are a few practical rules or suggestions that are\\nunconsciously kept in mind by the successful engineer, but are\\noften forgotten by the inexperienced.\\nMeans for adjusting all parts subject to wear, should be pro\u00c2\u00ac\\nvided.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0024.jp2"}, "25": {"fulltext": "MACHINE DESIGN.\\n23\\nMake the motion of all parts positive if possible avoid the\\nuse of springs and weights for producing motion.\\nProvide means for lubrication wherever necessary.\\nConstruct the parts that may wear or break so that they will\\nbe accessible for adjustment or repairs.\\nCranks, belts, levers and gear wheels are preferable to cams,\\nscrews and worm-wheels.\\nAvoid the use of tap bolts and studs use through bolts or T\\nhead bolts if possible.\\nIf convenient make the pressure per square inch on slides\\nsmall.\\nFASTENINGS.\\nBolts, Nuts, Keys, Cotters, etc.\\nA screw is a cylindrical bar, upon the surface of which a Heli\u00c2\u00ac\\ncal projection called the thread has been formed. A cylindrical\\nhelix is the curve generated by the revolution of a point about the\\nsurface of a cylinder, while moving along the axis at a constant rate.\\nA nut is a short hollow prism, upon the inside of which are\\nformed grooves which corre\u00c2\u00ac\\nspond accurately to the\\nthreads of the screw.\\nThe screw and nut when\\nused for fastening is called a\\nbolt. Screws are also used to\\ntransmit motion and to adjust\\nthe relative positions of two\\npieces. Screw threads are\\nusually triangular or square\\nin section. The Whitworth\\nand U. S. standard threads\\nare triangular. Square\\nthreads are used chiefly to\\ntransmit motion. There is\\nless friction and less wear\\nthan with triangular threads,\\nbut they are more expensive.\\nThe Standard Thread, Fig. 6, shows the American or Sellars\\ntriangular thread. The construction is shown enlarged by Fig. 7.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0025.jp2"}, "26": {"fulltext": "24\\nMACHINE DESIGN.\\nThe sides of the thread are inclined at an angle of 60\u00c2\u00b0. The sec\u00c2\u00ac\\ntion of the thread is an equilateral triangle having its top cut off\\nso that the flat portion is of the pitch in width. The angles at\\nthe bottom are filled in similarly. The real depth of the thread\\nis a little less than the altitude p of the triangle it is .65 p.\\nSharp Y threads are those cut without the flat top and bottom;\\nthe section being an equilateral triangle.\\nThe pitch of a screw is the distance the screw advances dur\u00c2\u00ac\\ning one revolution; it is the distance from one thread to the next.\\nAnother method of indicating the pitch is to give the number of\\nthreads per inch. For instance we say a screw has 11 threads\\nper inch; that is, it will advance one inch during 11 revolutions\\nor the pitch is -A- of an inch, or .091 inch.\\nThe pitch of threads depends upon the diameter of the bolt.\\nThe following equations give approximately the pitch, and the\\ndiameter at the bottom of thread in the U. S. standard.\\np .^4 d .625 .175 inch,\\nd 1 d 1.3 p d 2 p x\\nIn these formulas p pitch, d diameter of bolt, d x\\ndiameter at the bottom of the thread, and p 1 real depth of the\\nthread.\\nLet n the number of threads per inch then\\nn JL and d, d UL\\nP n\\nThe external diameter of a bolt is 1| inches, to find the pitch,\\nthe number of threads per inch, the diameter at root of threads\\nand the depth of thread we proceed as follows\\np .24 y/l.875 -J- .625 .175 .204 inch.\\nU 5 (about) which makes the pitch .20.\\nd 1 d 2 p x\\n2\\\\ Pl d dj\\nThen the pitch is or .2 inch: there are 5 threads per\\ninch, diameter at root of threads is 1.615 inches and the depth of\\nthread equals .13 inch.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0026.jp2"}, "27": {"fulltext": "MACHINE DESIGN.\\n25\\nThe following table gives the principal dimensions of U. S.\\nstandard or Sellars threads.\\nDiameter\\nof\\nBolt\\n(Inches;\\nNumber\\nof\\nThreads\\n(Per Inch.)\\nDiameter\\nat Bottom\\nof Thread.\\n(Inches.)\\nArea at\\nBottom of\\nThread\\n(Square Inches.)\\n1\\n20\\n.185\\n.0269\\nA\\n18\\n.240\\n.0452\\n3\\n\u00e2\u0080\u00a2g\\n16\\n.294\\n.0679\\nA\\n14\\n.345\\n.0935\\nh\\n13\\n.400\\n.1257\\nA\\n12\\n.454\\n.1619\\nI\\n11\\n.507\\n.201?\\ni\\n10\\n.620\\n.3019\\ni\\n9\\n.731\\n.4197\\nl\\n8\\n.838\\n.5515\\nn\\n7\\n.939\\n.6925\\nH\\n7\\n1.064\\n.8892\\nit\\n6\\n1.158\\n1.0532\\nH\\n6\\n1.283\\n1.2928\\nif\\n5*\\n1.389\\n1.5153\\nif\\n5\\n1.490\\n1.7437\\nH\\n5\\n1.615\\n2.0485\\n2\\nH\\n1.711\\n2.2993\\n2J\\n4\u00c2\u00a3\\n1.961\\n3.0203\\n4\\n2.175\\n3.7154\\n2|\\n4\\n2.425\\n4.6186\\n3\\n2.629\\n5.4284\\n8*\\n3i\\n2.879\\n6.5099\\n8j-\\n8J\\n3.100\\n7.5477\\n3|\\n3\\n3.317\\n8.6414\\n4\\n3\\n3.567\\n9.9930\\n4j\\nn\\n3.798\\n11.3292\\n4i\\n2i\\n4.027\\n12.7366\\n4 i\\n2*\\n4.255\\n14.2197\\n5\\n2*\\n4.480\\n15.7633\\n5j\\n4.730\\n17.5717\\n5*\\n2f\\n4.953\\n19.2676\\n5}\\n2f\\n5.203\\n21.2617\\n6\\n2J\\n5.423\\n23.0978\\nThe Whitworth triangular thread shown at D, Fig. 10, is\\nused in England. The angle between the surfaces is 55\u00c2\u00b0, and J\\nof the depth or altitude of the triangle is rounded off instead of", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0027.jp2"}, "28": {"fulltext": "26\\nMACHINE DESIGN.\\nbeing flat as in the Sellars thread. The pitch and diameter at\\nthe bottom of the thread is found as follows:\\np Md .04,\\nd, d .M .05.\\nn\\nA screw with a square thread is shown in Fig. 8 and an\\nenlarged section of the thread in Fig. 9. The pitch of the square\\nthread is usually double that of the triangular or V thread for a\\nbolt or screw of the same diameter. The pitch is about the\\nFig. 8.\\nFig. 9.\\ndiameter of the screw; the diameter at the bottom of the thread is\\nthe diameter of the screw and the depth of thread the pitch or\\n-jo tlie diameter of the bolt. The edges of the square thread are\\nslightly rounded to prevent flattening and to prevent binding of\\nthe nut.\\nIf the thread is to be subjected to very rough usage the\\nrounding is carried further so that the section of the thread is like", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0028.jp2"}, "29": {"fulltext": "MACHINE DESIGN.\\n27\\nthat shown at A, Fig. 10. The thread shown at B is like a square\\nthread, but instead of having a square section the thread tapers\\nfrom the root to the point. This taper is given to the thread\\nbecause it is easier to cut than a square thread. This form is\\noften used as lead screws for lathes. The taper allows the nut,\\nwhich is in two parts, to engage and disengage easily. The\\nA B C D\\nFig. 10.\\ntrapezoidal or buttress thread is shown at C. It is used for\\ntransmitting motion or when the force acts always in the same\\ndirection. One face is normal to the axis of the screw and the\\nother is inclined at an angle of 45 degrees. The top is usually\\ncut off and the bottom filled in as in the U. 8. standard thread;\\nthe amount being about the same, that is, about 4- the depth. The\\npitch is equal to the theoretical depth since the angle of the face\\nis 45 degrees. The real depth is about f the altitude of the\\ntriangle.\\nThe relative advantages of the various forms of threads; and\\nthe uses to which they should be put may be understood by con\u00c2\u00ac\\nsidering the forces which act on the faces.\\nIt has been proved that the greater the angle of the screw", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0029.jp2"}, "30": {"fulltext": "28\\nMACHINE DESIGN.\\nthread the greater the friction between the bolt and nut, and the\\ngreater the force tending to burst the latter.\\nThe friction of the square thread is less than that of the tri\u00c2\u00ac\\nangular thread because the angle between the sides is zero; there\\nis moreover, no force tending to burst the nut. The triangular\\nthread is, however, nearly twice as strong as the square thread.\\nFor the above reasons the square thread is better for transmitting\\nmotion and the triangular for fastening.\\nThe trapezoidal thread should be used only when the pressure\\ncomes on the side perpendicular to the axis. In this case the thread\\nhas the same friction as the square thread and the same strength as\\nthe V thread. If the pressure is put on the inclined side the friction\\nand bursting force are greater than is the case with the Sellars\\nthread having angles of 60\u00c2\u00b0 between the sides.\\nThreads are formed for both right handed and left handed\\nmotion. Usually they are right handed. To determine the motion,\\nhold the bolt or screw horizontal and turn it in the direction in\\nwhich the hands of a watch revolve. If it advances into the nut\\nor wood it is right handed. If when vertical the slope of the\\nthread is from right to left it is right handed. For nuts reverse\\nthe above rule.\\nriultiple Threads. In tracing the thread about the screw,\\nthe next thread is reached in one revolution, if the screw is single\\nthreaded. In other words, the nut will advance a distance equal\\nto the pitch for every revolution of the screw. If in tracing the\\nthread through a turn one thread is missed, it is a double threaded\\nscrew if two are missed it is a triple threaded screw, and so on.\\nMultiple threaded screws are used for transmitting motion,\\nwhen it is desirable to have the nut advance a considerable dis\u00c2\u00ac\\ntance for each revolution. This could also be accomplished by\\nmaking the pitch large; but the multiple thread is better. The\\ndiameter at the root of the multiple thread is greater than that of\\na single thread and therefore stronger. The pitch is the distance\\nthe screw advances during one revolution, or it is the distance\\nbetween two consecutive threads, if double threaded; or the dis\u00c2\u00ac\\ntance between three threads, if triple.\\nGas Pipe Threads. The Sellars thread is not suitable for\\nthe threads on gas pipe, for the calculated depth of thread would", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0030.jp2"}, "31": {"fulltext": "MACHINE DESIGN.\\n29\\nbe greater than the thickness of the pipe\\nsystem has been adopted having smaller\\npitch and cutting less deeply into the\\nmetal.\\nProportions of Bolts and Nuts.\\nThe diameter of the bolt determines the\\ndimensions of the nut. These dimen\u00c2\u00ac\\nsions may va!ry to suit circumstances.\\nSometimes in cramped places the nut\\nmust be made thin, or there must be\\nlittle metal around the screw threads, or\\nit must be made of peculiar shape. In\\naltering the shape or size of a nut, the\\ndesigner considers the strain put on it,\\nThe standard form is shown in Fig. 11.\\nThe head of the bolt is square. Some\u00c2\u00ac\\ntimes the neck (the portion next the\\nhead) is made square also, to prevent\\nrotation of the bolt when the nut is\\nbeing screwed up.\\nThe nut is hexagonal and the\\nwasher circular. The washer is used\\nwith rough castings to give a smooth\\nsurface on which to turn the nut. The\\nfollowing are the formulas for dimen\u00c2\u00ac\\nsions corresponding to the figure, d being\\nthe diameter of the bolt.\\nFor this work a special\\nFor Rough Work.\\nD l\\\\d 1\\nDj 1.73c? -f .14 for hex\u00c2\u00ac\\nagonal\\nD 1 2.12 d -f- .18 for square\\nd\u00e2\u0080\u009e n d\\nh d\\nt .15 d\\nFor Finished Work.\\nD =l|d J f\\nDj 1.73 d -f .07 for hex-\\nagonal\\nT 1 2.12 d .09 for sq.\\n1 2 U D,\\nt .15 d", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0031.jp2"}, "32": {"fulltext": "30\\nMACHINE DESIGN.\\nSTRENGTH OF SCREW BOLTS.\\nBolts are generally used when the straining force is in the\\ndirection of the axis of the bolt; that is, bolts are used for tension\\nstresses. It is evident that the effective area is not the area of the\\ncross-section of the bolt, but the area at the root of the thread.\\nLet P the total load on the bolt.\\nd 1 diameter at root of thread.\\na area of cross-section at root of thread.\\nS w safe working stress in pounds per square inch.\\nThen for tension\\nP a S w 7r _ ^1 S w f I\u00e2\u0080\u0099oni which a JL.\\n4 S w\\nThen d 1 2\\nThe values of a are found directly from the preceding table.\\nThe value of P we can usually calculate from the machine.\\nS w varies with the material and the conditions of stress if it is\\nconstant a good wrought iron bolt will stand 7,000 or 8,000 pounds\\nper square inch. For variable stresses, S w may be taken as about\\n5,000 or 6,000 pounds. Usually S w is taken as 4,000 or 5,000\\npounds. For bolts used in cylinder heads, S w varies from 3,000\\npounds per square inch for small to 6,000 pounds for large\\ncylinders.\\nSuppose we wish to find the diameter of a bolt to sustain a\\nsteady stress of 15,000 pounds, allowing 8,000 pounds as the work\u00c2\u00ac\\ning stress.\\nP _ 15,000\\nS w 8,000\\n1.875 square inches.\\nThe number 1.875 lies between 1.7437 and 2.0485 of the\\ntable. The larger value should be chosen, the diameter of the bolt\\nbeing 1-J inches.\\nEXAMPLES FOR PRACTICE.\\n1. What is the safe working stress on a bolt 1 inch in\\ndiameter, if the value of P is 3,850 pounds\\nAns. 7.000 pounds (about).", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0032.jp2"}, "33": {"fulltext": "MACHINE DESIGN.\\n31\\n2. Find the size of bolt used for varying stress. P 14,000\\npounds and S w 4,000 pounds. Ans. 2| inch holt.\\n3. An engine cylinder head is bolted to the\\ncylinder by 12 bolts. If the total steam pressure\\nis 48,000 pounds, what is the diameter of the bolts\\nS w being 4,250 pounds. Ans. 1| inches.\\nIt would take considerable time to make the\\nthreads of all the screws and bolts of working-\\ndrawings accurately. To save time a conventional\\nform, shown in Fig. 12, has been adopted. The\\nthreads are represented by alternately light and\\nheavy lines. The distance between these lines\\nneed not be equal to the pitch of the threads,\\nbecause, the diameter being given, the number\\nof threads per inch is found from the table. If\\nthe threads are not standard the number of threads\\nper inch is noted on the drawing.\\nWRENCHES.\\nForms of solid wrenches or spanners are\\nshown in Fig. 13. The dimensions are given in\\ndecimals of the diameter of the bolt. They\\nFisc. 12.\\nare made in many sizes, with ends shaped for hexagonal and\\nsquare nuts. The unit for the proportions is D.\\nFORMS OF NUTS.\\nThe most common form of nut is the hexagonal shown at A,\\nFig. 14 B shows the square nut. Usually both square and", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0033.jp2"}, "34": {"fulltext": "32\\nMACHINE DESIGN.\\nhexagonal nuts are chamfered off at an angle of 30 to 45.\u00c2\u00b0 Some\u00c2\u00ac\\ntimes they are finished with a spherical bevel, having a radius of\\nabout twice the diameter of the bolt. C shows a round nut hav\u00c2\u00ac\\ning holes in the sides into which a bar is inserted for tightening\\nFig. 14.\\nthe nut. The nut shown at D is called a cap nut; it is used to\\nprevent leakage past the screw thread. A thin copper washer is\\nsometimes used with this form of nut. E represents a flange nut\\nwhich is used when the hole in which the bolt is placed is consider\u00c2\u00ac\\nably larger than the bolt. The flange covers the hole and gives\\ngreater bearing surface.\\nFORMS OF BOLT HEADS.\\nFig. 15 shows several forms of bolt heads. The hemispheri\u00c2\u00ac\\ncal or cup-shaped head, a common form, is shown at A. At B is\\nFig. 15.\\nshown the hexagonal form. It is similar to the hexagonal nut\\nand has about the same dimensions except the height which is\\nusually less; it is from f d to d. The cylindrical bolt head is", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0034.jp2"}, "35": {"fulltext": "MACHINE DESIGN.\\n33\\nshown at C; rotation of the holt is prevented by the square neck.\\nD shows the spherical head; the bearing surface rests on a seat of\\nthe same shape. It is used when the bolt tends to lean toward\\none side. The head remains in contact with the seat for every\\nposition of the bolt. E shows a bolt with countersunk head;\\nrotation is often prevented by a set-screw.\\nFig. 16 is the hook bolt. It is used when a piece would be\\nFig. 16.\\nFig. 17.\\nweakened or is too small to have a drilled hole. Fig. 17 is a\\nT=headed bolt.\\nSet=screws are screws or bolts used to prevent by friction\\nrelative rotation between pieces. Set-screws are often used to\\nprevent the hub of a pulley from turning on the shaft. They\\nare screwed through the hub and prevent rotation by pressing\\nagainst the shaft. At A, Fig. 18, is shown the cone point set\u00c2\u00ac\\nscrew. The one shown at B is called the cupped set-screw; C,\\nthe headless cone point set-screw; and D, the roimd point set-\\nscrew.\\nA stud bolt is one that has threads cut on both ends. One", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0035.jp2"}, "36": {"fulltext": "34\\nMACHINE DESIGN.\\nend is screwed into one of the pieces to be connected and remains\\nin position when the nut is\\non or off. Fig. 19 shows a\\nstud bolt. They are some\u00c2\u00ac\\ntimes used for cylinder-heads\\nand valve-chest covers. A\\nstud with a collar is shown\\nin Fig. 20. The collar may\\nbe square or round; if square\\nit is a convenient place for a\\nwrench. The collar forms a Flgt 19, Fig. 20.\\nshoulder against which the stud may be screwed.\\nFig. 21 shows an ordinary method of\\nfastening a bolt to stonework. The head,\\nwhich is long, is made jagged with a cold chisel.\\nThe hole is made larger at the bottom than at\\nthe top and after the head is placed, the space\\naround it is filled with melted lead or sulphur.\\nFoundation bolts, which are used to fasten\\nan engine-bed to its foundation, are often fixed\\nas shown in Fig. 22. The head is formed by\\na cast iron washer and a cotter. This cotter\\npasses through a slot and has gib ends to pre-\\nFio 4 1 vent slipping. The washer jjrovides a large\\nbearing surface. The bolt, washer, and cotter\\nare placed in a recess in\\nthe wall and are acces\u00c2\u00ac\\nsible. The size of the\\nwasher is easily deter\u00c2\u00ac\\nmined. The area of the\\nwasher multiplied by the\\ncompressive or crushing\\nstrength of the stone or\\nbrick should be equal to\\nthe pull on the bolt.\\nThe tensile strength of\\nwrought iron is about Fi g. 22\\n55,000 pounds per square inch and the compressive strength of", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0036.jp2"}, "37": {"fulltext": "MACHINE DESIGN.\\n35\\nbrick is about 2,500 pounds per square inch, or about of that\\nof the bolt. Therefore, the bearing surface of the washer should\\nbe about 22 times the area of the cross-section of the bolt.\\nScrews. The three most common forms of machine screws\\nare shown in Figs. 23, 24, and 25. Fig. 23 is the countersunk\\nhead screw; Fig. 24, the fillister head and Fig. 25 the button\\nhead. The countersunk head is used when the head is not to\\nproject above the plate.\\nLOCKING ARRANGEMENTS FOR NUTS.\\nNuts never fit the bolt accurately; some clearance is neces\u00c2\u00ac\\nsary to permit them to turn freely. If a nut is subject to frequent\\nchanges of load and vibration it gradually unscrews or slacks\\nback. To prevent nuts from becoming loose various locking\\ndevices are used.\\nOne of the most common is the double nut called a locknut\\nFig. 28.\\nor jam nut shown in Fig. 26. There are two nuts, one about", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0037.jp2"}, "38": {"fulltext": "86\\nMACHINE DESIGN.\\ntwice as thick as the other. The outer nut should be the thicker\\nbecause the load is thrown on it. However, the thin one is often\\nplaced on the outside because the wrench is often too thick to act\\non it when it is inside. When the nuts are screwed home they\\nare locked together by being turned in opposite directions.\\nIn Fig. 27 the nut is kept in place by a split pin or cotter.\\nA hole is drilled through the bolt and the pin driven through and\\nthe ends turned over to prevent it from backing out. This is not\\na very good method because the nut must always be close to the\\npin.\\nAnother method is shown in Fig. 28. The nut is sawed\\nabout half way through and the parts closed slightly by a set\u00c2\u00ac\\nscrew, after the nut is screwed home. The nut then grips the\\nthread tightly. For small nuts the set-screw is not used but the\\nparts are closed, just before it is set, by a slight blow of a\\nhammer.\\nAt A big. 29 is shown a Grover\u00e2\u0080\u0099s spring washer. The upper\\nFig. 29.\\nportion of the figure shows the washer when not held down by the\\nnut. When the nut is screwed down tightly, the washer becomes\\nnearly flat and its elasticity increases the friction between the\\nthreads of the bolt and nut.\\nIn the device shown at B, Fig, 29, a stop plate is used. It\\nis fixed by a set-screw to one of the pieces through which the bolt\\npasses. It is shaped so that the nut may be locked at intervals of", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0038.jp2"}, "39": {"fulltext": "MACHINE DESIGN.\\n37\\niV \u00c2\u00b0f a revolution. The set screw may have a diameter equal to\\nd being the diameter of the bolt. The other dimensions are also in\\nterms of the diameter. For bolts set in a circle, the bolts of a\\ncylinder head for example, a circular stop plate, shown at C, Fig.\\n29, is used. It is placed inside the nuts and bears against one of\\nthe parallel sides.\\nThere are numerous methods of locking by set-screws, their\\nforms depending on the position of the pieces.\\nUsually bolts are used in tension, that is, when the strain\u00c2\u00ac\\ning force is parallel to the axis of the bolt. The joint pin is a\\nFig. 30.\\nbolt placed so as to be in shear. Fig. 30 shows a knuckle joint.\\nThe joint pin is made the same size as the rods because of wear.\\nIf the pin were subjected to simple shear at the two sections it\\nneed be only about .7 the diameter of the rod, but it soon wears\\nand is subjected to bending stresses also.\\nThe other proportions are in terms of the diameter of the rods.\\nd diameter of the rods.\\na =1.2 d\\nb 1.1 d\\nc .75 d\\ne .S d\\ni .6 d\\no 1.5 d", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0039.jp2"}, "40": {"fulltext": "38\\nMACHINE DESIGN.\\nKeys are small wedges, usually made of iron or steel, used to\\nfix wheels, cranks and pulleys to shafts. It is the duty of keys to\\nprevent the wheel or crank from rotating otherwise than with the\\nshaft on which it is keyed. For example, a crank is keyed to the\\nshaft in order that the shaft and crank will rotate together.\\nUsually the friction of the key in the keyway will also prevent the\\nwheel from sliding along the shaft.\\nKeys are usually plain rectangular pieces with their lateral\\nsides parallel and a tapering thickness. In case the small end is\\ninaccessible, that is, the arrangement is such that it cannot be\\ndriven out, the key is made in the form shown in Fig. 31. A\\ngib head is made at the large end which forms a shoulder to drive\\nagainst.\\nFig. 32 shows several forms of keys. The concave, or saddle\\nkey, is shown at A. The slot or keyway is cut in the wheel and\\nthe key hollowed to fit the shaft which is not cut at all. As the\\nkey holds by friction, it is suitable only for light work. The flat\\nFig. 32.\\nkey is shown at B. A flat surface is planed on the shaft having\\na breadth equal to that of the key. This form is more secure than\\nthe saddle-key. The sunk key shown at C is more effective than\\neither of the above forms because slipping is prevented unless the\\nkey shears. There are two forms of sunk keys, the rectangular\\nand the square. The rectangular form is used for fastening", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0040.jp2"}, "41": {"fulltext": "MACHINE DESIGN.\\n39\\ncranks, gear wheels, pulleys, etc. They are driven in tightly and\\nfit both at the top and bottom as well as the sides. As they fit\\non all sides they should not be used in accurate work because they\\nare likely to spring the work out of true. Square keys are used\\nfor accurate work; they fit accurately only on the sides. In case\\na pulley is accidentally bored a little too large for the shaft it is\\nfastened securely by using both a flat key and a sunk key as\\nshown at D. The two keys are placed at about right angles.\\nThe pulley and the shaft have a bearing at three points on the\\ncircumference of the shaft.\\nSometimes large wheels are keyed to the shaft by two, three\\nor four keys. When the shaft is square eight keys may be used.\\nIf they are arranged as shown in Fig. 33 no keyways need be cut\\non the shaft, and only the key seats are planed.\\nPin=keys. A round taper pin is used in place of a key for\\nsmall shafts; handles on valve stems for instance. The pin is\\nsunk half in the shaft and half in the piece, as shown in Fig. 34.\\nSometimes a secure connection, where the parts are not to be\\nseparated, is desired, as is the case with small cranks. The crank\\nis bored slightly smaller than the crank shaft, then expanded by\\nheat and shrunk on. It is further secured by a key or pin.\\nIn order that keys may be easily driven in and removed\\nthey are tapered slightly. The taper is about 1 in 64 to 1 in 150.\\nThe more accurate the work the less the taper. This method of\\nexpressing taper means that the decrease in thickness is -fa to\\nof the length. Sometimes taper is expressed in inches to the foot\\nas inch per foot.\\nSliding Keys. Sliding or feather keys are used if the piece", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0041.jp2"}, "42": {"fulltext": "40\\nMACHINE DESIGN.\\nis to be prevented from rotating but at the same time is to be\\nallowed to slide along the shaft. The key may be fastened to the\\npiece and free to slide in the keyway of the shaft, or it may be\\nfast to the shaft and the wheel free to slide. Figs. 85 and 36\\nshow the various methods of fixing the key. In Fig. 36 the key\\nis dove-tailed in section and is fastened to the hub. The one\\nshown in Fig. 36 is used when the hub comes against a collar or\\nbearing, since it does not project from the hub. The feather\\nkey of Fig. 35 has gib heads.\\nStrength of Keys. Saddle keys are used most where the\\nstress between the pieces is usually small. No exact rules can be\\ngiven as they depend on friction to prevent rotation.\\nSunk keys must resist both shear and compression. The\\ntwisting of the shaft tends to shear the key and crush it.\\nLet b width of key in inches.\\nI length of key in inches.\\nt thickness of key in inches.\\nS 8 allowable shearing stress in pounds per square inch.\\nS c allowable crushing stress in pounds per square inch.\\nd diameter of the shaft in inches.\\nr radius of wheel or pulley in inches.\\nF force in pounds acting at the rim.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0042.jp2"}, "43": {"fulltext": "MACHINE DESIGN.\\n41\\nThe resistance to shearing is the shearing area multiplied by\\nthe shearing stress, bl$ 8 To find the diameter of the key, take\\nmoments about the center of the shaft and solve for hi\\n2 d X blS 8 F r, from which bl\\nd S s\\nThe sunk key usually has the thickness in the shaft and\\nin the hub. In case the key is designed to be equally strong to\\nresist shearing and crushing the shearing strength must be equal\\nto the crushing strength.\\nThe resistance to shearing is blS 8 and the resistance to crush\u00c2\u00ac\\ning is equal to the product of the bearing surface and the stress,\\nor 1 tlS c\\nIf the crushing stress is assumed to be twice the shearing\\nstress, S c 2S s then b t and the key is square in section.\\nUsually the key is made wider than the thickness so that the\\nshearing strength shall be greater than the resistance to compres\u00c2\u00ac\\nsion, as there is little danger of crushing.\\nLet H. P. the horse-power transmitted.\\nN the number of revolutions per minute.\\nr the radius of wheel in inches.\\nThen as the circumference of a circle is 2 it r, a point on the\\ncircumference will move 2 ir r N inches or\\n2 7r r N\\n~T2\u00e2\u0080\u009c\\nfeet\\nper\\nminute.\\nThe power transmitted (assumed to be constant) will be the\\nforce acting, F, multiplied by the distance or,\\nF X\\nN\\n12\\nfoot-pounds.\\nOne H. P.\\nThen H. P.\\n33,000 foot-pounds per minute.\\n2,rrNF 33,000\\n12 198,000\\nor,\\nTrrNF\\nFr\\n198,000 X H. P.\\n198,000 H. P.\\nH. P.\\nF r 63,025", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0043.jp2"}, "44": {"fulltext": "42\\nMACHINE DESIGN.\\nFor shearing of keys the usual factor of safety is about 10\\nwhich gives an allowable stress of about 5,000 pounds per square\\ninch for wrought iron and about 7,000 pounds per square inch for\\n2F r\\nsteel. Inserting these values in the equation bl\\nd S t\\nbl\\nThen bl\\nFr\\nd X 2,500\\nFr\\nd X 3,500\\n25.2 H. P.\\nd X N\\nfor wrought iron\\nfor steel.\\nfor wrought iron\\n18 H. P.\\n__, tor steel.\\nd X N\\nSuppose the pressure on a crank-pin is 15,000 pounds and the\\ncrank is 12 inches long. If the shaft is 6 inches in diameter and\\nthe length of key 6 inches, what should be the dimensions of the\\nwrought iron key\\n2,500 d\\nb\\nFr\\n2,500 X l X d\\n15,000 X 12\\n2,500 X 6 X 6\\n2 inches\\nThen the key should be 2 inches broad. Its thickness is\\nusually some fraction of the breadth. We will make it or 1-t\\ninches. Keys vary in thickness from 1 to J of the breadth.\\nIn designing machinery, the dimensions are usually deter\u00c2\u00ac\\nmined by empirical formulas. For the ordinary sunk key b\\nd Yi ail d the mean thickness, t P to b.\\nIf we use these formulas for finding the dimensions of the key\\nin the above example, 5=-|d -JX 6 If inches.\\nt f l 1^ inches.\\nWhen pulleys are keyed to large shafts which transmit only\\na small amount of power, the dimensions obtained from the above\\nformulas are larger than necessary. In such cases the following\\nformulas are used.\\n-y\\n100 H. P.\\nN\\nor,\\nFr\\n360\\nThese values of d are inserted in the above formulas.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0044.jp2"}, "45": {"fulltext": "MACHINE DESIGN.\\n43\\nA pulley transmits 3 horse-power. It is keyed to a shaft 6\\ninches in diameter, which makes 130 revolutions per minute find\\nthe dimensions of the key.\\n\\\\d-\\\\~Y -455 or inch (about).\\nt t b i inch.\\nEXAMPLES FOR PRACTICE.\\n1. A shaft is 4 inches in diameter what is the breadth of\\nthe sunk key? Ans. 1^ inches.\\n2. Find the breadth of a steel key, when the length of the\\nkey is 4 inches, the horse-power transmitted is 100, the shaft is\\n4J inches in diameter and makes 100 revolutions. Ans. 1 inch.\\nCOTTERS.\\nA cotter is an iron or steel bar driven through one or both\\nof two pieces to be connected. It prevents their separation by its\\nresistance to shearing at two transverse cross-sections. Cotters\\nsometimes adjust the length of the pieces connected. They should\\nbe so designed as to decrease as little as possible the strength of\\nthe connected pieces.\\nFig. 37.\\nA and B of Fig. 37 show two views of a simple cotter. In\\nthis form the cotter passes through the rod. The cotter resists\\ntension. The collar or enlargement prevents movement in the", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0045.jp2"}, "46": {"fulltext": "44\\nMACHINE DESIGN.\\nother direction, and therefore resists thrust. An arrangement\\ndesigned to resist tension only is shown at C, Fig. 37. The\\ncotter has gib ends to prevent its moving out of place.\\nA construction to resist tension alone is shown at D and E of\\nFig. 38. This cotter is divided; one part with hooked ends is called\\nFig. 38.\\nthe gib and the other a plain cotter. Such a construction is often\\ncalled the gib and cotter. At F of the same figure, the rod is\\ntapered to provide for thrust.\\nCotters like those shown at D and E in Fig. 38 are long\\nand tapered and therefore may be used to adjust the length of the\\nconnected pieces. By driving the cotter in, the total length of\\nthe pieces is made less.\\nA cotter is often used to connect two straps, a and b to the\\nrod Z, as shown in Fig. 39.\\nIf a plain cotter is used the\\nexcessive friction between\\nthe cotter and the straps,\\nwhen the former is driven\\ndown, causes the lower strap\\nto open as shown by the\\ndotted lines. To prevent this\\na gib and cotter are used, or\\ntwo gibs and a cotter. The\\ngib prevents the strap from\\nspreading. In Fig. 40 the\\nside, a b, of the gib and the side, c d of the cotter are parallel to\\neach other and are at right angles to the straps. The parts of\\nthe gib and cotter that are in contact are tapered.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0046.jp2"}, "47": {"fulltext": "MACHINE DESIGN.\\n45\\nTaper of Cotters. A cotter that has a taper of more than 1\\nin 7 is likely to slack back. In general, the taper is from 1 in 24\\nto 1 in 48. If the cotter has a fastening device it may have a\\nmuch greater taper, i. e., 1 in 6 or 1 in 8. The taper of the cotter is\\nfound by dividing the increase in width by the length. Thus if\\na cotter is 2| inches in width at one end and 2| at the other the\\nincrease is i inch and if the cotter is 10 inches long the taper is J\\ndivided by 10 Aq or 1 i n 20.\\nStrength and Proportions of Cotters. In designing cotters a\\nfew facts must be remembered.\\nIn the following demonstration the letters refer to Fig. 42.\\nThe cross-section, b t, must be sufficient to stand the shear\u00c2\u00ac\\ning stress.\\nThe thickness, must be large enough to prevent crushing.\\nThe diameters should be so designed that the rod will not be\\nweakened by the cutting of the slot for the cotter.\\nLet F the force in pounds on the rod,\\nS t allowable tensile stress of the rod in pounds per square\\ninch,\\nS c allowable compressive stress of the cotter or rod in\\npounds per square inch,\\nS s allowable shearing stress of the cotter in pounds per\\nsquare inch,\\nThe net area of the rod is the area of a cross-section minus\\nthe area of the slot or,\\nnet area\\n7T d 2\\ndt\\nThe shearing area of the cotter is 2 b t. The area subject to\\ncrushing is d t. The area of the socket subject to tension is\\n2L (D 2 d 2 (D d) t.\\n7T V\\n4\\nThe area of the rod itself is\\nThen, as each of these values when multiplied by its", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0047.jp2"}, "48": {"fulltext": "46\\nMACHINE DESIGN.\\nrespective allowable stress must be equal to the force, F,\\nf\\n(a)\\nF 2i(S s\\nO)\\nF i S c\\n00\\nF= j\\nj\\n(D d) t\\nJ St, (d)\\nF V S t\\n00\\nIf the cotter is subjected to a\\nallowable stresses may be,\\nforce in one direction only, the\\nWrought Iron\\nS t 10,000\\nS s 8,000\\nS c 20,000\\nCast Iron\\nS t 2,800\\nS c 5,600\\nSteel\\nS t 18,200\\nS s 10,600\\nS c 26,400\\nIn case the forces act alternately in opposite directions the\\nstresses are found by dividing the above values by 2.\\nThe above values show that,\\nS,\\nSt\\ni and 2,\\nthen\\nS\\n5 01\\ns: r-\\nThen combining equations (b) and (c) and letting t d\\nwe have,\\n2btS 8 =:dtS c\\nor b J|s I d 1.25 d,\\nA O e\\nCombining (a) and (c)\\n7 r d 2\\nd t d t _5\\nSt\\nt \\\\d (about).\\nCombining (a) and (d) and taking t\\n7r d\\nj 7T d/ 2\\n(\u00e2\u0080\u009cT\\nit d 2\\n~w\\n8*\\nj-J- (D\u00c2\u00bb\u00e2\u0080\u0094i*)_(D \u00e2\u0080\u0094d)\\nD d.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0048.jp2"}, "49": {"fulltext": "MACHINE DESIGN.\\n47\\nTo have the same tensile strength D should equal d but to\\nprevent crushing, the bearing surface of the socket must equal\\nthat of the rod, or\\n(D d) t d t,\\nand D 2 d\\nCombining (a) and (e) and, as before, taking t\\n7 r d 2 7 r c? 2 c 7r d 1 2 Q\\nSt\\nd t .816 d.\\nSince the bearing surface of the collar should be equal to that\\nof the cotter in the rod,\\nJL. (d 2 2 d 2 d t, and since\\n_ 7 t d\\n12\\nd 2 1.15 d.\\nb l\\\\d\\nt \\\\d\\nD 2 d\\nd x .816 d\\nd 2 1.15 d\\na is made equal to c and is from f to l\u00c2\u00a3 d.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0049.jp2"}, "50": {"fulltext": "48\\nMACHINE DESIGN.\\nFig. 41 shows a cotter with double gib. In this case b t is\\nusually made the sectional area of the strap and t I b. b is\\nmade the same for all cases, whether a single cotter, gib and\\ncotter or two gibs are used. The other dimensions are,\\nb\\n6 T\\n1 5 6 5\\n0 t 5 t 5\\nl f l\\nIf a steel cotter is used in a wrought iron rod, b may equal d.\\nFig. 48 shows a small split pin. Split pins are forms of\\ncotters which are used to prevent two pieces from separating but", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0050.jp2"}, "51": {"fulltext": "MACHINE DESIGN.\\n49\\ntlo not connect them firmly. Large pins are made solid with a\\nslight taper.\\nLocking Arrangements for Cotters. Fig. 44 shows a method\\nFig. 44. Fig. 45.\\nof securing the cotter by a set screw. The cotter passes through\\nthe head of the gib and is held by the screw. A simple way to\\nsecure the cotter is by prolonging the gib and having a screw\\nthread cut on it as shown in Fig. 45. Nuts on each side of the\\nbent cotter keep it in place and adjust the length. In Fig. 46,\\nthe end of the cotter is a screw which passes through a recessed\\nwasher or extra seat. A nut above the washer holds it in place.\\nIn case a cotter has an excessive taper this method is sometimes\\nused to prevent slacking back.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0051.jp2"}, "52": {"fulltext": "50\\nMACHINE DESIGN.\\nEXAriPLES FOR PRACTICE.\\n1. Find the dimensions of a rod and cotter of the form\\nshown in Fig. 42. Assume S t 6,500 pounds. The load is\\n7,900 pounds.\\nd 1J inches\\nd^ 1| inches\\nd 2 1J inches\\nAns. D 3 inches\\nt inch\\nb lj inches\\na li to If inches\\n2. Two straps are connected to a rod as shown in Fig. 41.\\nIf the pull on the rod is 10,000 and S s 5,500 pounds, find the\\ndimensions of the cotter and gibs. Assume t i inch.\\n(t ^inch.\\nj width of cotter if inches.\\nns breadth of gibs li inches.\\n\\\\^b 3f inches.\\n3. What are the dimensions of a wrought iron cotter used\\nto fasten a wrought iron rod 2 inches in diameter\\na t i inch\\nns b 21 inches\\n4. A cotter is 1|- inches wide at the middle; it tapers on\\neach side. If it is 18 inches long and tapers inch to the foot\\nwhat is its width at each end\\nAns. 1^ inches and 1^ inches.\\nJOURNALS.\\nJournals are the portions of shafts and axles which turn in\\nbearings and are supported by the frame of the machine. They\\nare usually cylindrical but may be conical or spherical in form.\\nIf the journal is at or near the end of the shaft it is called an\\nend journal; if situated between two end journals it is called a\\nneck journal.\\nThe most common form for the bearing portion of a journal\\nis a true cylinder as shown in Fig. 47. Collars or shoulders at\\nthe ends bear against the ends of the brasses, in which the journal\\nrevolves, and limit the play lengthwise. In case a light end play", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0052.jp2"}, "53": {"fulltext": "MACHINE DESIGN.\\n51\\nis desired, as in the car journal for instance, the bearing is made\\nslightly shorter than the journal, thus permitting a little longitudinal\\nFig. 47.\\nmotion and causing uniform wear of the brasses. When longi\u00c2\u00ac\\ntudinal motion would interfere with the movements of other por\u00c2\u00ac\\ntions of the machine, it is made as small as possible.\\nThe methods for calculating the requisite size of a journal\\ndepend upon the velocity of the shaft and the constancy with\\nwhich it is run. In case it runs occasionally or at slow speed it\\nis designed for strength; but if it runs constantly at high speed,\\ndurability and freedom from heating are as important elements as\\nstrength.\\nJournals may be subjected to straining forces in the plane of\\nthe axis (causing bending and shearing stresses) and also to com\u00c2\u00ac\\nbined torsional and bending stresses.\\nWhen designing for strength the journal is considered as a\\ncantilever beam uniformly loaded.\\nIf l the length of the journal in inches,\\nd the diameter of journal in inches,\\nS the safe working stress,\\nI the moment of inertia,\\nc the distance of the fibre most remote from the neutral\\naxis,\\nW the total load in pounds,\\nw load per square inch in pounds\\nthen from Mechanics,\u00e2\u0080\u009d\\nC T\\nW 2 x\\nl c\\nand since for a circular section,\\n7T C? 4\\nI\\nand c\\n64", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0053.jp2"}, "54": {"fulltext": "52\\nMACHINE DESIGN.\\nthen,\\nw _ 9 S v 2 TT d* _ 7T cT 3 S\\nT \u00e2\u0080\u009c64 ~d 16T\\nand, 16 W l tt d s S\\nfrom which d\\nv/\\n16 W\\n7T S\\nThe equation is used in the above form because the ratio of\\nlength to diameter is usually assumed, i. e., fixed before the\\nd\\ncalculation is made. If this ratio were not assumed there would\\nbe two unknown quantities in the equation.\\nFor journals which work intermittently the ratio l to d is\\nusually 1, or 1. Where the speed is less than 150 revolu-\\nd\\ntions per minute varies from 1.5 to 1.75. The greater the\\nd\\nspeed the greater the proportion of length to diameter this causes\\na reduction of pressure per unit of bearing surface as the speed\\nincreases.\\nFor example. Find the length and diameter of a steel jour\u00c2\u00ac\\nnal, having a load of 2,000 pounds. Assume -i-to be 1.5 and the\\nd\\nsafe working stress, S, as 9,000 pounds.\\nd\\n16 W\\nv/\\n16 X 2,000\\n3.1416 X 9,000\\nX\\n1.3 inches.\\n2\\nIn this case the journal would be ly 5 g inches in diameter and\\n1 t6 X 1.5 2 inches long.\\nThe safe working stress varies with the conditions and the\\nmaterial. Average values of S are as follows:\\nMaterial.\\nSteel\\nWrought Iron\\nCast Iron\\nConstant Load.\\n12,000 to 13,000\\n7,000 to 9,000\\n3,500 to 4,500\\nVariable Load.\\n9,000 to 12,000\\n6,000 to 7,000\\n3,000 to 4,000\\nWhen designing to provide against heating, experience deter\u00c2\u00ac\\nmines the allowable pressure per square inch on the area of pro-", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0054.jp2"}, "55": {"fulltext": "MACHINE DESIGN.\\n53\\njection of the journal. This is called the projected area and is\\nequal to the length of the journal multiplied by the diameter, or,\\narea l X d.\\nThe load per square inch evidently is the total load divided\\nby this area, or,\\nW\\nw =_\\nl X d\\nIf the pressure per square inch w, is too large the lubricant\\nis squeezed out and the journal is likely to heat and increase in\\nsize. The better the lubricant, the larger w may be. For high\\nspeeds the pressure may be greater than for low speeds. In the\\ncase of journals, as for example, crank pins, where the pressure\\nalternates in direction the limit of pressure may be about twice as\\ngreat as where the load is in a fixed direction. This is because of\\nthe better lubrication in case of alternating direction.\\nSince W w l d, and W\\nit d s S\\n16 l\\n~r AZ Q\\nthen wld= or 7 t d 2 S 16 w\\n16 l\\nl 2 IT S l\\nand TS or\\nd 2 16 tv d\\nIT S\\n16 w\\nSubstituting this value of in the equation d\\nd V 7 r\\nthe result is, d 2y/\\n16W l\\nS ~d\\nw\\nsf ir S w*\\nand since w l d W,\\nW\\nl\\nw d\\nTherefore in calculating the diameter when the pressure w is\\nassumed we use the formula d\\n2 V /^UancU=\\n\\\\TT S W w a\\nfor\\nthe length.\\nFind the length and diameter of a steel journal when the", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0055.jp2"}, "56": {"fulltext": "54\\nMACHINE DESIGN.\\nload is 11,000 pounds. The safe working stress is 10,000 pounds\\nand the allowable pressure is 900 pounds.\\nFrom the formula we obtain;\\n_11,000_\\nv x l ,ono x\\nThe square root of nr 1.77245, then d 2.87 -f- inches,\\nand the shaft would be 8 inches in diameter. We also find\\nl\\nW\\nw d\\n11,000\\n900 X 3\\n4.07\\n4Ag inches long.\\nThe following table of limits of pressure per square inch of pro\u00c2\u00ac\\njected area for different conditions is taken from Unwin\u00e2\u0080\u0099s Machine\\nDesign.\\nPRESSURE ON BEARINGS AND SLIDES.\\nPressure Calculated in lbs. per sq. in. op Bearing Surface.\\nIntensity\\nof pres\u00c2\u00ac\\nsure, lbs.\\nper sq. in.\\nBearings on which the load is intermittent and the speed\\nslow, such as crank pins of shearing machines\\nCross-head neck journals.\\nCrank pins of large slow engines.\\nCrank pins of marine engines, usually.\\nMain crank shaft bearings Marine engines (slow)\\nMain crank shaft bearings Marine engines (fast)\\nBail way journals\\ni\\nFly wheel shaft journals.\\nSmall engine crank pins.\\nSlipper slide blocks, Marine engines\\nStationary engine slide blocks.\\nStationary engine slide blocks, usually.\\nPropeller thrust bearings.\\nShafts in cast-iron steps (Sellers)..\\n3000\\n1200\\n800 to 900\\n400 to 500\\n600\\n400\\n300\\n150 to 250\\n150 to 200\\n100\\n25 to 125\\n30 to 60\\n50 to 70\\n15", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0056.jp2"}, "57": {"fulltext": "MACHINE DESIGN.\\n55\\nNECK JOURNALS.\\nA neck journal is considered as a simple beam supported at\\nboth ends and uniformly loaded. The cross head pin, or wrist pin\\nis an example of this kind of journal.\\nFrom u Mechanics,\u00e2\u0080\u009d the equation for the above beam is,\\nW 8 JL X\\nl c\\nSince I and c\\n64 2\\nW 8 T x TF-\\nfrom which d\\n=V-\\n7T\\nW y l\\nS x d\\nThis formula is used to calculate the value of d when the\\nratio is assumed.\\nd\\nExample. Find the diameter and length of a wrought iron\\nneck journal when the load is 4,400 pounds, S assumed to be 8,000\\npounds and 2.\\nSolution, d\\n4,400\\nX 2.\\n3.1416 X 8,000\\n2 X -59 1.18 inches.\\nA l T 3 g inch shaft would probably be chosen.\\nThen, also, l 2 d, 2 X l T 3 e 2| inches.\\nAs in end journals W w d l and since W 8\\n32 l\\nequating the two values for W, we get,\\n8 S 7r d z\\nw l d\\n32 1\\n4 w l 2 7r d 2 S.\\nl 2 7T S\\nThen\\nd 2 4 w\\nand\\nd\\n7r S", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0057.jp2"}, "58": {"fulltext": "56\\nMACHINE DESIGN.\\nSubstituting this value of in the equation d 2 y/ X\\nwe get, d 2 v/\u00e2\u0080\u009c^ X\\n7T S\\n7T S\\n4 w\\nW\\nand reducing, d 2 v/\\nv/IttSw\\nas before,\\nW\\nw df\\nThe same values for S and w, given for end journals may be\\nused for neck journals.\\nSuppose we wish to find the length and diameter of a neck\\njournal having a load of 8,000 pounds. Let us assume S to be\\n8,500 pounds and the bearing pressure 500 pounds then,\\nW\\n8,000\\nV y/4 j S w V y/4 X 3.1416 X 8,500 X 500\\n2 y/l.09 2.08 inches.\\nA 2-| inch shaft would be used, and we also find\\n8,000\\nw d 500 X 2|\\n__ 7J inches (about.)\\nDIHENSIONS OF JOURNALS.\\nWe have already seen how the diameter and length of jour\u00c2\u00ac\\nnals are determined. Knowing the diameter, the height of the\\ncollar may be found from the formula h .1 d -J and the\\nbreadth equals 1| times the height.\\nUsually the journal is turned with a fillet in the corner, since\\nthe shaft is less likely to crack than if it has a square corner. The\\nradius of the circular fillet is about one half the height.\\nFRICTION OF JOURNALS.\\nIn every case, friction generates heat which causes the\\ntemperature of the journal to rise. This rise of temperature\\nincreases the size of the journal and causes unnecessary work.\\nIn order to diminish friction, the journal is lubricated, that\\nis, it is supplied with some lubricant (oil or fatty matter) which\\nforms a thin film between the journal and the bearing. The\\nlubricant diminishes friction and greatly reduces wear.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0058.jp2"}, "59": {"fulltext": "MACHINE DESIGN.\\n57\\nThe surface velocity in feet per minute of a journal is evi\u00c2\u00ac\\ndently the circumference of the circle whose diameter is d multi\u00c2\u00ac\\nplied by the number of revolutions ?i, or expressed algebraically,\\nSurface velocity feet per minute.\\nIf f the coefficient of friction, and W the load, the work\\nexpended in friction is expressed by the formula\\n7r dn\\nWork W X\\n12\\nfoot ponnds per minute.\\nAs we have seen from the table on page 54, the pressure\\nper square inch on the bearing surface cannot exceed certain\\nlimits. These limits varying with the kind of work done and the\\nspeed. For the load W a certain bearing surface dl is necessary.\\nThe value of the coefficient/varies greatly; it is dependent\\nupon speed, pressure, kind of metals, and kind of lubricant.\\nUnder some conditions it may be as low as .001 and under others .2.\\nFrom the above equation it is evident that the work used in\\nfriction is directly proportional to the diameter of the shaft. This\\nfact shows that under a constant load it is well to obtain a large\\nprojected area, d by increasing l and making d as small as is\\nconsistent with strength.\\nSuppose we have two journals, 1| inches in diameter and 4|\\ninches long; the other 3 inches in diameter and 2.25 inches long.\\nThey have the same projected area, i.e 6.75 square inches; but\\nthe work required to overcome friction of the first is only one-half\\nas much as for the second.\\nAlthough the first, i. e., the 1-| inch journal is preferable for\\na steady load, it is not as strong as the three inch journal, and the\\nlatter should be used for high speeds and when the journal is sub\u00c2\u00ac\\nject to shocks.\\nPIVOT AND COLLAR JOURNALS.\\nIn journals already considered the\\ndirection of pressure is perpendicular to\\nthe axis of the shaft; in the pivot journal\\nshown in Fig. 48 the direction of pressure\\nis parallel to the axis. With end journals\\nthe bearing surface is the cylindrical Fig. 48.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0059.jp2"}, "60": {"fulltext": "55\\nMACHINE DESIGN.\\nsurface but in pivot journals it is circular, and is the area of the end\\nof the pivot. To find the diameter of such a journal knowing the\\nload, assume a value for the pressure per square inch of bearing\\nsurface and solve for the area. This may be expressed by the\\nformula,\\nw 7T d 2\\nW \u00e2\u0080\u0094_\u00e2\u0080\u0094 X w\\nSuppose the total load is 32,000 pounds and the allowable\\npressure on the bearing surface is 650 pounds per square inch.\\nWhat is the diameter?\\nW f 2 X W, and 32,000 X 650.\\n4 4\\nt r\\nThen __\u00e2\u0080\u0094 the area 49.23 square inches.\\nand d 7.9 inches.\\nAn 8 inch shaft would be used.\\nIn cases where the speed is not very high we may use the fol\u00c2\u00ac\\nlowing as maximum values of w:\\nWrought iron on gun metal 700 pounds\\nCast iron on gun metal 470 pounds\\nWrought iron or steel on lignum vitae 1,400 pounds\\nFor high speeds with iron or steel on lignum vitae bearing,\\nwhen moistened with water, the following formula may be used,\\nd .035 y/W7\\nThe direction of load for a collar bearing is parallel to the\\naxis but the bearing area is formed by a collar or collars on the\\nshaft. Fig. 49 shows a journal with one collar and Fig. 50 one\\nwith several collars. To find the diameter of collars for propeller\\nshafts we proceed as follows:", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0060.jp2"}, "61": {"fulltext": "MACHINE DESIGN.\\n59\\nLet d diameter of shaft,\\nD diameter of collar,\\nN number of collars,\\nw pressure per square inch of projected area,\\nW total load.\\nThe total load is expressed by the equation,\\nW 1 7T (D 2 d 2 N w.\\nUsually w is taken as 50 or 60 pounds for propeller shafts.\\nUsing iv 60 the formula becomes,\\nW 7T (D2 _ d 2 15 N,\\nW\\n15 ttN*\\nor (D* d 2\\nHence D y d 2\\n15 7T N\\nThe number of collars is determined by the designer. By\\nincreasing the number, the diameter, wear and friction are de\u00c2\u00ac\\ncreased but if too many collars are used all the thrust may be\\nbrought on a few of them. The distance between collars is\\nsometimes equal to the thickness. But if the encircling rings are\\nlined with white metal or are made hollow the distance may be\u00e2\u0080\u0099 1\\nmade about twice the thickness.\\nEXAMPLES FOR PRACTICE.\\n1. What are the proportions of a wrought iron end journal,\\nwhen 1.2, the load 1,800 pounds, and safe stress 8,500\\nd\\npounds? Ans. l-j 3 X 1 T V\\n2. Find the length and diameter of an end journal when S\\n9,000 pounds, W 8,000 pounds and w 800 pounds.\\nAns. 8f 3 X 2f\\n8. Find the proportions of a neck journal, if the load is\\n7,000 pounds, the bearing pressure 400 pounds and safe stress\\n9,000 pounds. Ans. 2^ X 81\\n4. Find the proportions of a neck journal if the load is\\n6,000 pounds, the safe stress 8,500 pounds and J\u00e2\u0080\u0094 1.75.\\nd\\nAns. X 2J/.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0061.jp2"}, "62": {"fulltext": "60\\nMACHINE DESIGN.\\n5. Find the power used in friction when the load is 6,000\\npounds, the diameter of the shaft 2 inches, and making 150 revolu\u00c2\u00ac\\ntions per minute. The coefficient being .002.\\nAns. 942.48 foot-pounds per minute.\\n6 Find the diameter of a wrought iron pivot running at 90\\nrevolutions per minute, with a load of 850 pounds, having gun\\nmetal bearings. Ans. li inch shaft.\\n7. Find the diameter of the collars on an 8 inch shaft, the\\nend thrusts being 18,000 pounds. There are four collars.\\nAns. 12.6 inches. Use 12J inches.\\nSHAFTS.\\nShafts are parts of machines which support rotating pieces.\\nThey are usually circular in section.\\nShafts may be divided into three classes. The classification\\nbeing determined by the kind of stresses to which they are\\nsubjected.\\n1. Shafts subjected chiefly to torsion or twisting. For\\nexample, shafting used to transmit power, called line shafting.\\n2. Shafts subjected chiefly to bending; shafts of gearing\\nexample.\\n8 Shafts subjected to both torsion and bending, as engine\\nshafts.\\nShafts of the first class, those subjected to torsion, must be\\ndesigned for both strength and stiffness. If a shaft is of large\\ndiameter or if it is short it may be designed for strength only; but\\nfor a long shaft of small diameter, sufficient strength may not\\ninsure sufficient stiffness. Line shafting is the name given to the\\nlong continuous lines of shafting used in mills, factories, etc.\\nNumerous pulleys are keyed to the shafts from which power is\\ntaken by belts and gears. These shafts are strained by twisting\\nstresses and also by a slight bending action due to the weight and\\nthe downward pull of the gearing.\\nCalculations for size are made by investigating the twisting\\nmoment which is equal to the force or pull multiplied by the\\nradius.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0062.jp2"}, "63": {"fulltext": "MACHINE DESIGN.\\n61\\nt rom the study of Mechanics\u00e2\u0080\u009d we know that the diameter of\\na round shaft may he found from the formula:\\nin which d the diameter in inches,\\nH z= the horse-power transmitted,\\nn the number of revolutions per minute,\\nand S s the constant of torsion and is:\\n2,000 pounds per square inch, for timber.\\n25,000 pounds per square inch, for cast iron.\\n80,000 pounds per square inch, for wrought iron.\\n75,000 pounds per square inch, for steel.\\nAnother formula for ordinary wrought iron mill shafting, is:\\nd\\nH\\nn~X .01153\\nThe following table has been computed from this formula;\\nby multiplying the second column by the number of revolutions\\nper minute, the result is the power the shaft will transmit.\\nDiameter\\nof Shaft\\nin inches.\\nH. P.\\nDiameter\\nof Shaft\\nin inches.\\nH. P.\\nn\\nn\\nIf\\n0.0623\\n5\\n1.4536\\n2\\n0.0930\\n1.9344\\n0.1325\\n6\\n2.5112\\n21\\n0.1817\\n3.1944\\n2 f\\n0.2418\\n7\\n3.9888\\n3\\n0.3139\\nH\\n4.9056\\n8 J\\n0.3993\\n8\\n5.9536\\nH\\n0.4986\\nH\\n7.1440\\n3f\\n0.6132\\n9\\n8.4800\\n4\\n0.7442\\n10\\n11.6288\\n4f\\n0.893Q\\n11\\n15.4752\\n41\\n1.0600\\n12\\n20.0896\\n4f\\n1.2470\\nHollow Shafts. The inner fibres of a shaft, that is, those\\nnear the centre are not as useful to resist torsion as the outer.\\nTherefore, in making a shaft hollow considerable weight is removed\\nand the strength is but little impaired. In other words, if a shaft\\nis made hollow its weight is decreased in a greater measure than", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0063.jp2"}, "64": {"fulltext": "62\\nMACHINE DESIGN.\\nits strength. A hollow shaft is much stronger than a solid one of\\nthe same weight. For marine work hollow shafts are especially\\nvaluable on account of their light weight.\\nLet D the outside diameter of the hollow shaft.\\nd the diameter of a solid shaft having the same\\nstrength as the hollow shaft.\\nDj the inside diameter of the hollow shaft.\\nFrom a mathematical consideration of moments and stresses\\nthe following formula is deduced:\\nSuppose we wish to find the diameter of a hollow shaft which\\nshall have the same strength as a solid shaft of nine inches diam\u00c2\u00ac\\neter, the internal diameter to be the external.\\n9 X 1.022 9.198 inches.\\nThe shaft may be made 9^ inches in outside diameter and\\n4^| in inside diameter.\\nThe distance between bearings depends upon the number of\\npulleys on the shaft. If the shaft has several pulleys keyed to it\\nthe bearings must be nearer than if there are only a few pulleys.\\nLarge pulleys and those giving out a large amount of power should\\nbe placed near the bearings. The distance should be such that\\nthe deflection can not be more than yj-g of an inch per foot.\\nThe following table gives maximum distance between bear\u00c2\u00ac\\nings for shafts of various sizes.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0064.jp2"}, "65": {"fulltext": "MACHINE DESIGN.\\n63\\nDiameter\\nof Shaft\\nDistance between Bear\u00c2\u00ac\\nings in Feet.\\nin inches.\\nWrought\\nIron Shafts.\\nSteel\\nShafts.\\n2\\n15.46\\n15.89\\n3\\n17.70\\n18.19\\n4\\n19.48\\n20.02\\n5\\n20.99\\n21.57\\n6\\n22.30\\n22.92\\n7\\n23.48\\n24.13\\n8\\n24.55\\n25.23\\n9\\n25.53\\n26.24\\nSHAFT COUPLINGS.\\nSince it would be inconvenient to manufacture shafts long\\nenough for a large factory, some means must be provided to join\\nshort lengths together.\\nShafting is usually made in lengths of 20 to 30 feet, and\\njoined by shaft couplings. These couplings should be placed near\\nbearings and on the side farthest from the power. If this is done\\nthe running part is supported even if a length is disconnected.\\nCouplings are made in various shapes according to the posi\u00c2\u00ac\\ntions of the shafts to be joined. They may be designed for shafts\\nhaving a common axis of rotation, that is, in line; for parallel\\nshafts or for shafts whose axes intersect.\\nShaft couplings are usually divided into three classes.\\n1. Mixed or permanent couplings, which can be discon\u00c2\u00ac\\nnected only by slacking keys or by removing nuts.\\n2. Loose or disengaging couplings, which are provided with\\narrangements for throwing a part of the shafting out of gear with\\nslight effort.\\n3. Friction Couplings which are loose and so arranged that\\nthey put the shafting into gear gradually and slip if the resistance\\nis great.\\nThe simplest form of shaft coupling is the box or muff shown\\nin Fig. 51. A short iron cylinder is fitted over the ends of the\\nshafts. Relative rotation is prevented by a wrought iron key\\nwhich is usually half in the shaft and half in the coupling. The", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0065.jp2"}, "66": {"fulltext": "64\\nMACHINE DESIGN.\\nshafts may be enlarged at the ends so that there will be no\\ndecrease in strength because of the key way. Couplings are\\ndesigned from empirical formulas and not from calculations for\\nstrength. In Fig. 51 d the diameter of the shaft, and is\\ntaken as the unit.\\nThe dimensions may be calculated from the formulas,\\nl 2ld+2\\nand t .45 d -f- 1\\nFor the key,\\nb {d\\nt \\\\d.\\nFor example. Find the dimensions for a box coupling for a\\nshaft 3 inches in diameter.\\nI a 21 x 3) 2 91 inches\\nt .45 d -j- 1 1.85 or 1| inches.\\nThe key would be,\\nb 4 inch\\nt 1 inch.\\nThe coupling shown in Fig. 52 is called the clamp coupling.\\nIt is made of cast iron, is easily removed, has no projecting parts\\nFig. 52.\\nand on account of its cylindrical shape can be used as a pulley.\\nThe faces of the joint are first planed then the holes are drilled.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0066.jp2"}, "67": {"fulltext": "MACHINE DESIGN.\\n65\\nIt is bored out after the two halves are bolted together with paper\\nbetween them. When the paper is removed a slight space is left\\nbetween the halves so that the coupling grips the shaft when the\\nparts are bolted together. The key is straight and fits only at the\\nsides so that it will not exert bursting pressure on the coupling.\\nThe following formulas may be used in finding the proportions;\\nd being the unit.\\nD 2i d\\nl 3 to 4 d.\\nllie bolts may be inch in diameter for shafts under 2J\\ninches in diameter and or inch for larger shafts. Usually\\nfour bolts are used for small and six bolts for large shafts.\\nFind the dimensions for a clamp coupling for a 3|- inch\\nshaft.\\nI) 2|- d -f- Y 9J- inches.\\nI 3 d lOi- inches.\\nWe can use 6 bolts of inch.\\n\u00e2\u0080\u00a2The flange coupling is shown in Fig. 53. The cast iron\\nflanges are keyed to the ends of the shafts to be connected. The\\nflanges are then brought face to face and bolted together. Some\u00c2\u00ac\\ntimes the flanges are faced in a lathe to insure a good joint. One\\nflange is often made to enter the other, as shown in the figure, to\\nprevent the shafts from getting out of line. As in the other shaft", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0067.jp2"}, "68": {"fulltext": "60\\nMACHINE DESIGN.\\ncouplings, the ends of the shrifts may he enlarged for the key way.\\nFor designing, d the diameter of the shaft, which is taken as\\nthe unit.\\nI) =2 1 d+ 2\\n1 2d.\\nNumber of bolts, n 3 the nearest whole number.)\\nrfi V\\nn\\no H+r-\\nPropeller shaft coupling. The coupling shown in Fig. 54 is\\nusea for propeller shafts. In this case the hollow steel shaft is\\nflanged at the ends and joined by bolts. Let d the diameter of\\nan equivalent solid shaft. Then,\\nd =(/5EW\\nD\\nThe number of bolts is usually\\nassumed, and the diameter d v can be computed by a consideration of\\nthe twisting moment of the shaft and the shearing strength of\\nthe bolts.\\nD 2 If d\\nA 2 d\\nd_\\ne ~2\\nThe bolts are made tapered.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0068.jp2"}, "69": {"fulltext": "MACHINE DESIGN. 67\\nLet n the number of bolts, and a a constant; then d 1 =ad.\\nThe values of a for different values of n are as follows\\nn 3\\n1 4\\n1 5\\n1 6\\n1 1 I.\\n1 9\\n1 19\\na .318\\n.283\\n.258\\n.239\\n.224 .212\\nI .201\\n.192\\nh ind the dimensions of a shaft coupling for a hollow pro\u00c2\u00ac\\npeller shaft 4 inches in external diameter and 2 inches in internal\\ndiameter using 8 bolts.\\n3 /44 _ 04\\nd y- 3.915 inches.\\nD 2 If X 3.915 6|- inches (about).\\nA 8 inches (about).\\ne 2 inches (about).\\nd x .212 X 3.915 if.\\nBolts f inch in diameter would be used.\\nSellars Cone Coupling. A convenient coupling for shafts of\\nequal or unequal size is shown in Fig. 55. It consists of an outer\\nFig. 55.\\ncylindrical box or muff which is turned of double conical form on\\nthe inside. Two sleeves, the exterior of which are conical and fit\\nthe conical surfaces of the box, are placed between the box and\\nthe shaft. The inside surfaces of the sleeves fit the shaft. Three\\nsquare bolts parallel to the shaft and resting in slots cut in the\\nsleeves, press them together. The sleeves are cut through on one\\nside at the bottom of one of the bolt slots. This gives sufficient\\nelasticity so that the sleeves may be drawn inward and grasp\\nthe shaft tightly. Each sleeve exerts the same force on the shaft\\nand with the aid of a key prevents slipping. The keys fit at the", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0069.jp2"}, "70": {"fulltext": "68\\nMACHINE DESIGN.\\nsides only. These couplings are easily disconnected if the parts\\nare well oiled before they are put together. The dimensions may\\nbe found from the following formulas\\nD\\nl\\nb\\na\\nsize of bolts d 1\\nIn the above formulas\\n3\\n4\\nd\\n\\\\d\\nd is the unit, and is taken as the\\ndiameter of the shaft. The conical sleeves have a taper of about\\n4 inches per foot of length.\\nThe Oldham Coupling. Fig. 56 shows a form of coupling\\nused when two shafts are parallel. A disc is keyed on the end\\nof each shaft. Between these discs lies a third which has a\\nf -5!-\\nK\\nb\\nt\\nu_j\\n1\\ns\\n\u00e2\u0096\u00a0\u00c2\u00ab1\u00e2\u0080\u0094 c\\n#\u00e2\u0080\u0094e\u00e2\u0080\u0094Xj\\nX\\nj-\\nmJ\\nFig. 56.\\nfeather on each side fitting in a slot in the corresponding disc.\\nThe middle disc revolves around an axis parallel to the shafts and\\nmidway between them. The shafts and disc have equal velocities.\\nThe proportions for this coupling may be as follows:\\nd diameter of shaft,\\na Ad\\nb 1.75 d,\\nc .8 d,\\ne .7 d,\\ni .25 d,\\nt= 3 d.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0070.jp2"}, "71": {"fulltext": "MACHINE DESIGN.\\n69\\nThe Universal Coupling. In case two shafts are not in line\\nthey may be connected by a universal coupling shown in Fig. 57.\\nFig. 57\\nThe velocity ratio varies but little if the angle is small. They\\nare constructed of wrought iron and may have the following pro\u00c2\u00ac\\nportions d being the unit.\\nd diameter of the shaft,\\na d to 2 d,\\nb If d,\\ne If d,\\ne =\\\\d,\\n9 2tf,\\nh d.\\nLoose Couplings are used if shafts are to be connected and\\ndisconnected. A type called a claw coupling which somewhat\\nresembles the flange coupling is shown in Fig. 58. It is used for\\nlarge slow turning shafts, which always revolve in the same direc\u00c2\u00ac\\ntion. This form is easily put in gear. In place of the flanges\\nthere is a set of projections or lugs which fit into recesses. One\\npart is firmly keyed to the shaft by a sunk key; the other is\\nfastened by a feather key. The part having the feather key (on\\nthe left hand) is prolonged and a groove cut for a lever with\\nwhich to slide it back and forth.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0071.jp2"}, "72": {"fulltext": "TO\\nMACHINE DESIGN.\\nA coupling which is easily put in gear hut can drive only in\\none direction has its claws shaped as shown in Fig. 59.\\nThe dimensions may be as follows:\\nd diameter of shaft,\\na =i d,\\no \u00c2\u00a7d,\\ne 4 d,\\ni 1 J d,\\nl l i d to 6 d.\\nFriction Couplings, or clutches serve instead of loose coup*", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0072.jp2"}, "73": {"fulltext": "MACHINE DESIGN.\\n71\\nlings on shafts running at high speeds. Fig. GO shows a good\\nform of friction clutch. The ring, g, is keyed to the shaft t.\\nThis ring is split and fits inside the cylinder c, which is keyed to\\nthe shaft i. Ihe split ends are connected by a screw having\\nright and left hand threads. The link d, connects the lever b, to\\nthe sleeve or collar a. The lever 5, turns the screw. The clutch\\nis readily operated. When the sleeve is pushed toward the cylin\u00c2\u00ac\\nder c, the rotation of the screw throws the ends h of the ring\\napart, and causes the ring e to press firmly against the cylinder c.\\nThe proportions for the various parts are about the same as\\nthose for Fig. 58. The clutch shown in Fig. 62 is not as good as\\nthat of Fig. 60 because it causes an end thrust on the shaft and it\\nis harder to put in gear. It is, however, simple in construction.\\nWeston Friction Coupling. The friction coupling shown in\\nFig. 61 is used both as a shaft coupling and for coupling a spur\\nwheel to a shaft. The wheel B has a long hub and wrought iron\\nrings or plates which slide on feathers. The clutch box A is fitted\\non the shaft, slides on feathers, and is moved by a lever working in", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0073.jp2"}, "74": {"fulltext": "72\\nMACHINE DESIGN.\\nthe groove E. Inside the box A are six feathers upon which are\\nstrung alternately wooden and wrought iron rings. If the coup\u00c2\u00ac\\nling box A is pressed to the left there is friction at each face\\nbetween the rings. The wheel B is prevented from moving end\u00c2\u00ac\\nwise by the collar C. One of the great advantages of this coup\u00c2\u00ac\\nling is that if a sudden load comes on the spur wheel B, the plates\\nmerely slip over each other; if rigidly connected, some part\\nwould break.\\nFig. 62 shows a simple form of friction coupling or clutch.\\nIt is used to couple wheels or pulleys to shafts and for loose\\ncouplings for shafts running at high speeds. It consists of a cone\\nkeyed rigidly to one shaft and a movable cone sliding on a feather\\non a second shaft. The movable portion should be placed on the\\ndriven shaft so that it will be at rest when out of gear. If the\\nresistance of the driven shaft is considerable the mean cone radius\\nmay be three or four times the diameter of the shaft. One great\\nobjection to this form is that the horizontal component of the\\npressure between the conical surfaces causes end thrust on the", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0074.jp2"}, "75": {"fulltext": "MACHINE DESIGN.\\n73\\nshaft. The angle of the cone may be from 4 to 10 degrees. The\\nother proportions are as follows:\\na diameter of shaft,\\nb If a,\\nc 1| a,\\nd 2 a,\\nA 4a to 8a,\\ni i a i\\nt 2 a.\\nShifting Gear for Clutches. Forked levers, having prongs\\nwhich fit into the groove of the clutch, are used to put clutches in\\nand out of gear. The lever is ordinarily worked by hand. Some\u00c2\u00ac\\ntimes a brass strap is made to encircle the groove; this increases\\nthe wearing surface. The following dimensions refer to Fig. 63\\nthe unit being the diameter of the shaft.\\na the diameter of the shaft,\\na T 5 g\\nb $e 9\\ni", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0075.jp2"}, "76": {"fulltext": "", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0076.jp2"}, "77": {"fulltext": "EXAMINATION PAPER.\\nMACHINE DESIGN PART I.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0077.jp2"}, "78": {"fulltext": "", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0078.jp2"}, "79": {"fulltext": "L, \u00c2\u00abf c.\\nMACHINE DESIGN\\nInstructions to the Student. Place your name and full address at the\\nhead of the paper. Work out in full the examples and problems, showing each\\nstep in the work. Mark your answers plainly u Ans.\u00e2\u0080\u009d Avoid crowding your\\nwork as it leads to errors and shows bad taste. Any cheap, light paper like\\nthe sample previously sent you may be used. After completing the work add\\nand sign the following statement.\\nI hereby certify that the above work is entirely my own.\\n(Signed)\\n1. A wheel 42 inches in diameter makes 35 revolutions per\\nminute. What is the linear velocity of a point on the circumfer\u00c2\u00ac\\nence? Ans. 6.4 feet per second.\\n2. If the angular velocity of a wheel 6 feet in diameter is 30\\nper second, what is the linear velocity Ans. 90 feet per second.\\n3. Define reciprocating motion, continuous motion, and\\nintermittent motion.\\n4. What is a machine?\\n5. Why are the relative movements of the parts of a\\nmachine independent both of the power transmitted and the size\\nof the parts\\n6. Define power and its unit.\\n7. Why are not foot-pounds an indication of Horse-Power?\\n8. Name some forms in which potential energy may exist.\\n9. What is the energy of a body weighing 20 pounds and\\nmoving with a velocity of 4 feet per second\\nAns. 4.97 foot-pounds.\\n10. In designing an engine why would you make the piston\\nrod of wrought iron or steel rather than of cast iron\\n11. Explain with sketch why all corners of castings should\\nbe well rounded.\\n12. Why are castings weak if some parts are much heavier\\nthan others\\n13. What elements and processes are employed to get sound\\nsteel castings", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0079.jp2"}, "80": {"fulltext": "MACHINE DESIGN.\\n14. Name tlie principal strains in machines and the methods\\nused in designing to allow for these strains.\\n15. What metals are used for hearing alloys?\\n16. If you were making a working drawing of an engine\\ncrank, how many views would you make\\n17. When are sectional views used?\\n18. Which is the best method of designing, by theory, or\\npractice, or by a consideration of both\\n19. Name some part of a machine that is designed from cal\u00c2\u00ac\\nculation for strength. Some part designed to provide for wear.\\n20. Describe with sketch the standard U. S. screw or bolt\\nthread.\\n21. What is the safe working stress on a bolt if the diame\u00c2\u00ac\\nter is 1^ inches and the load 8,800 pounds? Ans. 4,2 3 pounds.\\n22. Why are multiple threads used when motion is to be\\ntransmitted\\n23. Describe the standard bolt and nut.\\n24. Why is the Sellars thread not suited for gas pipe\\n25. An engine cylinder-head is bolted to the cylinder with\\n8 bolts. If the maximum total steam pressure on the piston is\\n28,000 pounds, what is the diameter of the bolts Assume safe\\nworking stress as 5,000 pounds. Ans. 1^ inches in diameter.\\n26. What is the pitch of a screw?\\n27. If a bolt is 11 inches in external diameter, what is the\\npitch? Find by formula. Ans. .185 inches.\\n28. Describe the Whitworth thread.\\n29. When are taper threads used What is the advantage\\nof the buttress thread\\n30. Describe with sketch some method of fastening founda\u00c2\u00ac\\ntion bolts.\\n31. What is a key?\\n32. Describe the knuckle joint.\\n33. Is the Grover\u00e2\u0080\u0099s spring a good locking device Why?\\n34. Describe with sketch what you consider a good locking\\narrangement for nuts.\\n35. When are pin keys used\\n36. Describe the method of fastening small engine cranks\\non shafts.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0080.jp2"}, "81": {"fulltext": "MACHINE DESIGN.\\n79\\n37. Why are keys tapered About how much is the taper?\\n38. What is the most effective form of key? Why?\\n39. Find the length of a steel key which is an inch wide\\nwhen a 3 inch shaft transmits 50 hcrse-power at 100 revolutions\\nper minute. 4ns. 3 inches.\\n40. Find the dimensions ot a cottei and rod of the form\\nshown in Fig. 42. The load being 5,500 pounds and S t 7,000\\npounds.\\n(d 1| inches\\n1^=1 inch\\nd 2 ly 6 inches\\nAns. I) 2.1 inches\\nt inch\\nb l^g inches\\na to l T 9 g inches.\\n41. Make a sketch of a locking device for a cotter that lias\\nconsiderable taper.\\n42. A cotter is 2 inches wide at one end and 2|- at the other.\\nIf it is 14 inches long what is the taper per foot?\\nA ns. inch per foot.\\n43 Find the length and diameter of a steel end journal when\\nChe load is 2,300 pounds. Assume 1.75 and the safe work-\\nd\\ning stress S, as 8,500 pounds. Ans. ly 9 g in. diam. and 2-| in. long.\\n44. Find the proportions of a steel end journal when the\\nload is 10,000 pounds, the safe working stress 9,000 pounds, and\\nthe allowable pressure 850 pounds. Ans. 2-| X 4\u00c2\u00a3 inches.\\n45. Find the diameter and length of a wrought iron neck\\njournal when W 5,000, S 7,500 and L. 2.\\nAns. ly 5 in. diam. and 2| in. long.\\n46. What is the height and breadth of collar for the above\\njournal Ans. in. in height and in. in breadth.\\n47. What is the diameter of a pivot journal when the load\\nis 25,000 pounds and the allowable pressure is 600 pounds per\\nsquare inch? Ans. 7f inches.\\n48. The end thrust on a 9 inch shaft is 12,000 pounds.\\nFind the diameter of the collars assuming 5 are used.\\nAns. D lli inches.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0081.jp2"}, "82": {"fulltext": "80\\nMACHINE DESIGN.\\n49. What is the diameter of a mill shaft which transmits 55\\nhorse-power at 90 revolutions per minute? Ans. 3i| inches.\\n50. Why is a hollow shaft stronger than a solid one of equal\\nweight\\n51. Find the outside and inside diameters of a hollow shaft\\nthat equals in strength a solid shaft 8 inches in diameter. The\\ninside diameter to he J the outside. Ans. 8^ and 4^ inches.\\n52. Why is the distance between bearings small\\n53. Describe with sketch a good simple shaft coupling.\\n54. Draw a sketch and calculate the dimensions of a clamp\\ncoupling like that shown in Fig. 52. The shaft being 4 inches\\nin diameter.\\nOPTIONAL\\nFor students taking Hechanical Drawing.\\nAssume convenient scale.\\n1. Design and draw a knuckle joint having d 2 inches.\\n2. Design and make two sectional views of a cotter like the\\none shown in Fig. 42. Assume d 1| inches.\\n3. Make a drawing of some form of shaft coupling for a 3\\ninch shaft.\\n4. Design and make the drawings of a friction coupling for\\na 3| inch shaft.\\n5. Design and draw a Sellar\u00e2\u0080\u0099s Cone coupling for a 2^ inch\\nshaft. Two views.", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0082.jp2"}, "83": {"fulltext": "V", "height": "4622", "width": "3003", "jp2-path": "machinedesign00amer_0083.jp2"}, "84": {"fulltext": "", "height": "4128", "width": "3253", "jp2-path": "machinedesign00amer_0084.jp2"}}