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Re-shoeing Steel Driving Wheels.

2nd July 1908, Page 6
2nd July 1908
Page 6
Page 6, 2nd July 1908 — Re-shoeing Steel Driving Wheels.
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Which of the following most accurately describes the problem?

The steel shoes on the driving wheels of tractors and steam wagons are likely to work loose, and eventually to drop off, or to become too thin to be of any further service for the purpose for which they were intended. It is then necessary to have new shoes fitted to the wheels.

-Before the tractor is taken off the road for this purpose, a sheet-iron template of the shoes should be made, and from this and the number of shoes to each wheel the quantity of bar or plate which will be required can be ascertained. The material should be ordered, and the shoes cut to shape, before the machine is actually stopped working. The requisite number of rivets should also be noted and ordered in readiness. For heating the rivets, a piece of steel plate about k' inch thick, and large enough to take six or more rivets 'at one time, is placed flat on the fire, and the rivets are inserted in the holes. The heads are thus protected to a great extent from the heat of the fire.

The wheels must now be taken off the machine, and the old shoes can be cut away by laying the wheel down on the edge of the rim while the heads are cut off, and the shanks of the rivets punched out from the inside of the rim. Figure I (a) shows the shape of punch which is used for cutting off the rivet heads. It is held by a hazel rod, which is twisted round to form a handle, and it is struck with a sledge-hammer the striker should stand well away from the direction the heads are likely to fly. Figure I (a) shows a form of punch which is used for removing the rivets when the heads have been cut off.

After all the shoes are removed, and all the rivets are punched out, any burrs round the holes should be chipped off flush with the rim, in order that each shoe may be bedded down along the whole area of contact, If this precaution is neglected, the shoe will very quickly work loose. The shoes, which have previously been cut off, should be of such a length as, when fixed on the wheel, to be a little less than the width of the tire, and the ends of these shoes should also be slightly bevelled, as is illustrated in Figure 2, which view shows two plates marked off on a short length of bar, so that, after the bevel is cut off the end, the bar is turned over, and the next one cut off from the opposite side. The object of this bevel is to prevent, as much as possible, the edges of the shoes from burring over, and so leaving ragged projections.

The shoes may now be "offered up," to ascertain how they bear on the rim of the wheel, and, if it is found that they do not fit fairly,they will have to be made red hot, and laid in the position they ultimately have to occupy. In this position, they should be gripped by a good stiff boiler cramp, secured at each end, as shown in Figure 3. The plate can then be bedded down, by carefully hammering it with a sledge-hammer, taking care to keep the pinching screws of the cramps quite tight. Before removing the cramps, carefully number each shoe, and affix a corresponding number on the rim, so that it can be replaced in the same position again when finally riveting it. The holes for the rivets can be marked off from the inside of the wheel while the shoe is clamped to the rim. The positions of the rivet holes are then carefully marked with a centre tool, and are then ready for drilling. This should be done with extreme care, otherwise it will be found thai the positions of the holes in the shoes do not agree with those in the wheel. If there is any discrepancy in this direction, it will be necessary to use either a smaller rivet, or to drift the two holes until they coincide.

After the shoes have been drilled,they will have to be counter sunk from the opposite side. A counter sink should be made in the same way as an ordinary drill, but the cutting edges should be ground with considerably less taper. The holes in the shoes must be counter sunk to within 1. inch of the under side of the shoe, as shown in Figure 4,which also shows approximately the angle of the counter sink. The wheel must now be chocked up to prevent its moving while the shoes are riveted on. Each shoe is first secured in place with bolts and nuts, which are screwed up tight, in order to ascertain whether the shoe is well bedded down before riveting.

A "dolly " is now required for holding against the round or snap head of the rivet while it is being hammered over ; this tool should be as heavy as is consistent with ease of handling', but, at any rate, it should be heavier than the riveting hammers. A piece of round shafting, which is provided with an eyebolt for the purpose of slinging it from the top of the wheel, or a flogging hammer, make excellent substitutes, in the absence of a special "dolly." It is also advisable to have in readiness a slightly-tapered round drift, to drive into the drilled holes, to make sure of their correct register. When everything is in readiness, a few rivets may be put into the fire, on the drilled plate to which reference has already been made, and they must carefully be watched in order to prevent their becoming too hot, although, on the other hand, if they are not hot enough when taken from the fire, they will practically be cold before the points of the rivets are properly hammered down ; the rivets should be of a white heat, when taken from the fire.

One of the bolts by which the shoes are temporarily secured should now be taken out, and the "holder up" must quickly insert the hot rivet through the hole, in which it is held by one of the strikers with a pair of hollow tongs until the " holder up " places the " dolly " against the head; in bringing this up, the head of the rivet should be given a sharp thump, to ensure that the head has bedded well down. The "dolly " should then be kept hard up against the bead, until the rivet is upset by the strikers. The first two blows should be struck on the shoe, close against the rivet; the first few blows on the rivet should be comparatively light ones, and the strength of the blows should be increased as the rivet fills out the hole. If these operations are done properly, the last indications of red should be leaving the metal as the rivet is closed up; the hammering should now cease, because there is danger of the rivet's becoming loose again if any further hammering is allowed. The cooling of the rivet, when properly fitted, causes it to contract slightly in length, and the shoe and the wheel rim are thus drawn tightly together.

The above-described process is repeated until all the shoes are riveted on, after which they should be carefully examined by tapping with a hand hammer, and, if any loose rivets are discovered, they should be cut out and replaced by fresh ones. If it is necessary to drill any holes through the shoes, to take the pins which secure the paddles, or frost spikes, thew holes should be drilled through the shoe a little larger in diameter than the holes in the rim of the wheel, because of the liability of the shoes to burring. After a wheel has been re-shod in this manner, it is advisable to carry a few countersunkheaded bolts, which may be used temporarily in the event of breakage of any of the rivets. The bolts should, however, be replaced by new rivets at the earliest possible opportunity.

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