serted by a process of hot riveting when the wheel is again assembled, taking care to use a rivet set in order to make a properly shaped head.

Houk Wire Wheel.-Many recent models of automobiles will be found equipped with wire wheels of some form or other. Improvements have been made in the method of lacing wire wheels so that the forms used for automobiles are very strong. This is due to a method known as triple spoke lacing as this provides a combination that permits the wheel to support radial, torsional, side thrust, and shock stresses in a much superior manner to the old double spoke lacing formerly used on light automobiles and widely applied on bicycles and motorcycles. Practically the only trouble that can occur in a wire wheel is breakage of the spokes and as most wire wheels are of readily detachable form it is only necessary to remove the defective members and replace them with new spokes, care being taken not to tighten the spoke nipple unduly and thus pull the rim out of true. The rims of the wire wheels used on automobiles are for the most part very strong and are not so likely to be pulled out of true as the lighter rims of bicycles or motorcycles are.

If a large number of spokes are broken as might result from a collision or other accident it will be advisable after replacing the spokes to true up the rim. This is done by revolving the wheel and holding a piece of chalk or crayon nearly against the wheel rim to indicate the high points where the wheels run out. These points may be eliminated by screwing in on some of the spokes and loosening on others until the wheel runs true. This requires some degree of skill but can be easily accomplished after a little practice. The spokes are usually of high tensile strength steel wire having a button head at the lower end where they fasten to the hub and a threaded upper end which screws into the nipple which draws the spoke taut and which fits in a countersunk hole in the steel wheel rim.

A typical triple spoke wheel of Houk manufacture is shown at Fig. 413, A, while the method by which it is fastened to the master hub is clearly shown at Fig. 413, B. Most wire wheels are made so as to be easily detachable from a master hub which is not re

moved from the wheel spindle or axle and which is supported by the bearings or axle shafts. The wire wheel is built up with an auxiliary pressed steel hub as a basis which is provided with a series of holes to fit over driving pins attached to the flange of the master hub and which is formed on the inside with two tapered seats, the angle of the tapers being opposed to each other. One of the male tapers forms part of the master hub which is shown at B in place on the front wheel spindle while the other male taper is

on the locking nut. When the lock nut is screwed onto the threaded end of the master hub, which is sometimes termed the inner or fixed hub, it forces the female taper on the inside of the pressed steel wheel hub against the male taper on the master hub. The torsional force is applied to the wheel through substantial driving pins which engage with registering holes in the hub flanges.

These drive pins as well as the hub are treated with a special rust-proofing process and the pins are nickel plated, rendering corrosion or sticking of the parts difficult. If the wheels have been kept on for a time and have not been disturbed it is likely that

some trouble may be experienced due to rusting of the pins as even the nickel plating will not protect these at all times. The rust may be easily cleaned off when the wheel is removed and a repetition of the trouble avoided by greasing the pins liberally before the wheel is again replaced on the master hub. The construction of the automatic locking nut which is a feature of the Houk wheel is clearly shown at Fig. 414. The hub at A is a rear hub attached to a semi-floating drive axle while that at B shows the conventional

arrangement for a front wheel or the hub of a full floating rear axle. These nuts are threaded for a loose running fit on the thread and have their conical end slotted into segments which allows a slight compression when forced into the conical seat of the hub shell. By virtue of the fact that the nuts are threaded loosely on the master hubs there is a difference in the circumferential length of the thread. If the nut is not drawn up tightly through neglect, the wheel supporting the weight of the car would bear upon the nut and as the wheel and hub turn when the car moves forward *he nut must turn by a sort of epicyclic action which will cause the

threads to wedge together under the pressure of the load and after the manner of a cone clutch prevent slippage between the threads. This forces the nut to lag behind the angular travel of the hub parts and consequently to screw itself tighter on the threads when they are properly positioned on the car. On the right hand side of the car the hubs must be provided with left hand threads while on the left hand side the hubs have right hand threads. When the nuts are once in place there can be no creeping action, as they clamp tightly down on the main thread owing to the slight compression of the segments in the conical end of the hub.

Dunlop Wheel.-The Dunlop wheels which are shown at Fig. 415, have attained great popularity in Europe and are now being used to some extent in this country. This wheel is very quick in operation and is locked in place positively as soon as installed. The inner hubs are made of bar stock for the front wheels and drop forgings for the rear, no castings being employed. As is true of all wire wheels, the hub is composed of two pieces, one, which is a master hub intended to remain in permanent assembly with the supporting bearings while the outer or removable hub to which the spokes are fastened is readily detachable. The outer hub is prevented from turning on the inner one by serrations or teeth which are located near the conical surfaces at the inner end of the hub. These teeth are external on the inner hub and internal on the outer and are formed to fit between each other. The engaging portions of the teeth are rounded off to enable them to slip easily in mesh. A second conical surface at the outer end of the outside hub rests on the hub cap, which is locked in place in the outer portion so that it cannot drop out when that part is removed from the inner hub, but at the same time it is free to turn in order to screw on the inner portion. As the locking of the hub cap from unscrewing determines the safety of the wheel from coming off this is an advantageous point.

A cup shaped member is placed inside of the outer end of the inside hub, this is kept from turning in the hub by serrations similar to those between the two portions of the hub, but is free to slide in and out within certain limits and is normally pressed outward by a coil spring. At the outer end are more serrations, formed to fit