01 



WHEEL MANUFACTURE. 



WHEEL MANUFACTURE. 



802 



is stated above; but it is only when the metal is of a particularly 

 mild quality, or has been prepared especially for the purpose by 

 softening. The following mode of softening the steel to be cut is a 

 very good one, and may be frequently adopted with great advantage : 

 Envelope the articles in a mass of loam, clay, or lime, with sufficient 

 moisture to make it adhesive, taking care that the articles to be 

 softened have a considerable thickness of the material all round them. 

 Heat the mass gradually to a blood-red heat ; keep it at this heat as 

 long as convenient, and let it remain in the fire to cool gradually as the 

 fire goes out, after which the articles may be removed, and will be 

 found more uniform in texture and easier to be cut than before being 

 subjected to the operation. In making cutters, as well indeed as any 

 other edge-tools, the susceptibility of receiving and retaining a keen 

 edge will be considerably increased by subjecting the steel to great 

 condensation, by cold hammering, previous to the process of hardening, 

 and more especially if the scale left after forging be first removed with 

 a file. Harden in water, but do not heat your steel too hot ; for every 

 degree that steel is heated above its hardening point deteriorates its 

 quality. 



WH EEL MANUFACTURE. The simplest form of wheel that can 

 be used for any purpose is that of a plain circular disc, such as might 

 be procured by a transverse section of the trunk of a tree of tolerably 

 regular form. Solid wooden wheels are still occasionally used in 

 machinery, but if large they are usually formed of two or three thick- 

 nesses of planking fastened together, with the grain crossing in various 

 directions. Wooden wheels for millwork, when not required to be 

 solid, usually have the periphery formed of segments, the inner sides 

 or edges of which are left straight. The periphery may consist of 

 three thicknesses of planking, each composed of six or eight such seg- 

 ments ; and if the three thicknesses are properly break-jointed, a wheel 

 of considerable strength may be thus produced. The arms, or radii, of 

 the wheel are fitted to the inner or straight sides of the segments by 

 bolting or other modes of fastening. Wooden wheels are occasionally 

 morticed into their shafts or axes ; but a preferable plan is to use four 

 arms, arranged in two pairs crossing at right angles, and halved into 

 each other in the centre, where their intersection leaves a square open- 

 ing for the shaft. This opening should be somewhat larger than the 

 shaft itself, and the difference of size should be made up by the inser- 

 tion of wedges, which afford the means of adjusting the wheel per- 

 fectly true upon the axis. In very large wheels, such as water-wheels, 

 two complete sets of clasp arms, one on each side of the wheel, are 

 used. In mounting face-wheels it is not unusual to add stays or braces 

 from the back of the wheel to a point at some distance along the shaft, 

 to resist the tendency of the trundle or pinion to force the wheel 

 out of its true position at right angles with the shaft. Hornbeam 

 is considered to be the best kind of wood for the cogs or teeth of 

 wheels. 



In modern machinery cast-iron has almost entirely superseded the 

 use of wood for cog-wheels of every description. If they do not ex- 

 ceed eight or ten feet in diameter, they may be cast in one piece ; but 

 if above that size it is desirable to form them into two or more parts, 

 because of the difficulty of cooling a very large casting without unequal 

 contraction. Where the diameter does not exceed twelve or fourteen 

 feet, the rim may still be formed in one piece, and the centre and arms 

 m another, the two to lie united by bolts ; but when those dimensions 

 are exceeded, a further subdivision is necessary. The rim may then 

 be cast in three segments, the box or centre in one piece, and the arms 

 in several pieces, each terminating in a rib forming half the thickness 

 of an arm, for convenience of bolting together. Large iron wheels are 

 adjusted accurately on their axes by wedges or keys ; but small ones 

 may, in many cases, be adjusted by turning the periphery in a lathe 

 after mounting. 



Carriage-wheels are those in which the greatest ingenuity of con- 

 struction is called fur, as they are eSJMMd to strains far greater for 

 their size and weight than almost any others. The peculiar nature of 

 these strains requires not only that the wheels be made exceedingly 

 strong, but also that they possess a degree of elasticity sufficient to 

 enable them to bear the violent concussions to which they are con- 

 tinually exposed, without risk of fracture or without the starting of 

 any of their numerous joints. An ordinary carriage-wheel consists of 

 the nave, a cylindrical block of wood, usually elm, which forms the 

 centre of the wheel, and is pierced longitudinally with n hole to 

 receive the axle ; the tpnkei, which are radiating arms t'nmed into the 

 nave at equal distances ; and the felloes, which are circular segments 

 framed on to the outer extremities of the spokes, and forming collec- 

 tively the periphery or rim of the wheel. The external surface of the 

 felloes is usually protected by a covering of iron, called the tire, which 

 ith'T be put on in several pieces, or straket, the joints of which 

 are made to alternate with those of the felloes, or in a single piece, 

 forming a hfxijt-tiri'. The simplest form in which such a wheel as here 

 alluded to could be formed, would be that in which the spokes would 

 i at right angles with the axis, and would form a flat or plane 

 figure when the wheel is viewed edgewise ; but such a wheel would be 

 ill adapted to meet the lateral shocks to which a carriage-wheel is 

 exposed. The more common form is tliat called the rfwt/ierf-wheel, in 

 which the centre or navu is made to fall back a little from the plane of 

 the felloes, so that the face of the wheel is not flat, but slightly con- 

 cave. The elasticity of this form is a very great recommendation. 



It possesses also this advantage : that if the axle be slightly bent 

 downwards towards its extremity, so as to bring the spokes of 

 the lower half of the wheel into a nearly vertical position, which 

 will enabls them to bear the greatest possible weight, the upper 

 half of the wheel will have such an inclination outwards as to leave 

 more room for the body of the carriage, and to throw particles of 

 dirt, caught up in its revolution, away from it. Very strong wheels 

 are occasionally made in a double-dished form, or with the spokes 

 alternately inclining outwards and inwards from the felloes, so that the 

 centre or nave of the wheel forms the base of a pyramid of which the 

 felloe forms the apex ; but such wheels are very deficient in elasticity, 

 and consequently will not bear much concussion. In ordinary dished 

 wheels the spokes are arranged in two sets, being alternately more and 

 less inclined or dished ; and in some cases every alternate spoke is set 

 absolutely straight or square with the nave. The dished form of 

 wheel, together with the bending of the axle, involves some increase 

 of axle friction, and also, if the wheel be wide, the use of a conical 

 tire, which cannot possibly roll in a straight line without a degree of 

 rubbing friction most injurious to the road, and which also increases 

 the draught. Some years ago the use of conical wheels for waggors, 

 combined with the inordinate breadth of tire encouraged by injudicious 

 legislation, was carried to a most absurd extent, and broad-wheeled 

 waggons were used which were far better adapted for grinding stones 

 into dust and mud than for the purpose of locomotion. This extrava- 

 gance, however, is now seldom seen. , 



The ordinary mode of making a coach-wheel is as follows. The 

 piece of elm tor the nave is turned in a lathe to the proper size and 

 shape, and is hollowed within to receive the axle. It is then fixed in a 

 groove, and holes are chiselled out for the reception of the ends of the 

 spokes. There is nothing but the practised eye of the workman to 

 guide him in making these holes in the proper position for producing 

 the disltinrj of the wheels ; half of the spokes are near one end of the 

 nave, and half near the other, and the holes have to be regulated 

 accordingly. The pieces of oak for the spokes are shaped by hand : a 

 small cutting tool, called a spoke-share, being the chief instrument 

 employed. Une end of each spoke is formed into a tenon to fit the 

 mortice-hole in the nave. The spokes are fixed into the holes by driv- 

 ing with a mallet, and are finally shaped after fixing. The rim being 

 formed of several felloes, and each felloe being large enough to receive 

 the ends of two spokes, the pieces of ash to form them require to be 

 wrought into segments of curves ; this is done by means of pattern- 

 boards and various cutting tools. The felloes are drilled with holes to 

 join them together by means of dowels, with other holes to receive the 

 ends of the spokes. 



Few mechanical operations of equal complexity, and requiring an 

 equal amount of precision, have received so little aid from machinery 

 as the manufacture of carriage- wheels ; though wheels made by 

 machinery are said to be superior in truth, firmness, and durability to 

 any others. In ordinary wheels the neatness and strength are 

 increased by the application of a hoop of iron to each end of the nave, 

 to enable it the better to resist the strain of the spokes. The spokes, 

 which are usually formed of oak saplings, are wrought into the proper 

 form after being driven into the nave, and are usually cut to a narrow 

 edge in front to lighten their appearance. Wheels have been made 

 with the periphery in one or two pieces, bent into the required form 

 after being softened by boiling and steaming ; but the plan has not 

 been found successful, because, among other disadvantages, the wood 

 is injured by the long boiling required. In ordinary coach-wheels, 

 from 4 feet i! inches to 4 feet 8 inches high, there are fourteen spokes ; 

 and in fore-wheels, which are about a foot lower, there are commonly 

 twelve spokes ; and the usual arrangement is to have half as many 

 felloes as there are spokes. The introduction of solid or hoop tires is 

 a great improvement upon the former system of wheel-making, as it 

 affords the means of binding the whole of the wheel together with 

 irresistible* force. The tire is made very hot, and the ' wheel is made 

 of such a size as only just to receive.it when it is thus expanded ; but 

 so scon as the hoop is brought into its proper place, water is thrown 

 upon the wheel to cool the tire, and to prevent the wood-work from 

 catching fire, and the result of the sudden contraction of the hoop is 

 to compress the felloes, and to force each spoke into a slightly curved 

 form, so that when complete the wheel forms a flat dome-shaped 

 figure, admirably adapted, by its combined strength and elasticity, for 

 the purpose for which it is designed. The tire is further secured, after 

 cooling, by a few pins driven through it and the felloes, and riveted 

 inside the latter. 



Having found, during his experiments on steam locomotion upon 

 common roads, that wheels of the ordinary construction were not 

 strong enough for his purpose, Mr. Hancock contrived and patented a 

 wheel in which the nave is abandoned altogether, and the inner ends of 

 the spokes are formed into wedges which abut against each other, and 

 t'nii a kind of arch surrounding the axle-box. They arc firmly 

 secured in their places by an iron plate on each side of the wheel, and 

 a bolt passing through each spoke. Though too rigid for very rapid 

 motion, this wheel is exceedingly strong, and its simplicity of construc- 

 tion forms a great recommendation. 



The rapid motion of railway carriages, coupled with their great 

 weight, so greatly increases the effect of such concussions as must 

 occur on even the smoothest road, that wooden wheels have been found 



