If the brake lining is worn it should be removed by chipping off the rivets and driving them out of the hole in the brake band. A piece of new lining is cut to the proper length and holes are drilled through it to coincide with those in the brake bands. The best method is to drill only two holes at a time and fit the lining carefully to one end of the brake band, then drilling in the next two rivet holes and after the lining is securely fastened in place to go on to the next rivets. It is important to use copper rivets having reasonably large heads that will not pull through the material and to countersink the material enough so the rivet heads will be firmly embedded below the surface so as not to come in contact with the brake drums. Some cases of slipping brakes have been traced to projecting rivet heads which did not permit the friction lining to come into contact with the brake drums.

A simple fitting which can be placed in an ordinary bench vise for riveting against is clearly shown at Fig. 409, B. This is an ordinary steel drift having a flat point of the same size as the rivet head. The fitting shown at Fig. 410, A, may be placed in a common vise or may be formed to fit the pritchell hole in an anvil. This piece may be made of mild steel though the punch H which is the same size as the rivet head can be made of tool steel. The body of the tool is flattened out on the under side where it rests on the anvil or bench vise top and is left oval on the top. A 3-inch hole is drilled in the top and tool steel punches of the form shown at H may be driven in place, some arrangement being made by which the punch may be driven out and replaced by a new one if it becomes broken or by one of smaller size if different rivets are used. A hammer and an ordinary rivet set are used to set the rivets as shown in the lower portion of the illustration. Copper rivets are easily headed up and neat heads may be formed without trouble. Never use iron or steel rivets for holding brake linings in place as projecting heads may wear grooves in the brake drums. The only remedy for grooved brake drums or members that have worn thin is replacement with new ones.

CHAPTER X

WHEELS, RIMS AND TIRES

Wood Wheel Construction-Houk Wire Wheel-Dunlop Wheel-Rudge-Whitworth Wire Wheel-Solid Tire Forms-Pneumatic Tire ConstructionThe Cord Tire Rims for Pneumatic Tires-Tools for Tire RepairsHow Tires are Handled-Small Vulcanizers-Shop Vulcanizing Equipment Supplies and Materials for Tire Repair Work-How Tires Are Often Abused-Why a Tire Depreciates Rapidly-Water Rots FabricTire Tube Repairs-Replacing Valve Stems-Simple Casing RepairsCasing Repairs Made from Inside-Retreading and Rebuilding Tires— The Dry Cure Method-Air Pressures and Carrying Capacity-Increase in Pressure by Heat-Carrying Capacity of Solid Tires-Metric Sizes and American Equivalents.

THE repairing of automobile tires is work that is usually left to the specialist whereas it can be very profitably done by the average garage man if the necessary equipment is installed. The tools, supplies and apparatus needed are not expensive and the skill required is much less than that needed to do the mechanical work incidental to the repair of the engine and other vehicle parts. Before considering the subject of tire repairing it may be well to review briefly the various forms of wheels and tire retaining rims on which the tires are mounted. The tire repair processes will be considered from the point of view of those who desire to make only temporary repairs or take care of roadside accidents as well as including the more complete instructions necessary for making permanent repairs by vulcanizing processes. The equipment illustrated for doing the work is typical and has proven satisfactory in practical use.

Wooden Wheel Construction.-The most popular form of wheel to have received general application on all classes of automobiles is the wooden spoke member of the same type as used on gun carriages and for that reason termed the artillery wheel. Various steps in making the parts of the wheel and also the processes of

Fig. 411. Showing Steps in the Construction of a Wooden Automobile

Wheel.

wheel assembly are shown at Fig. 411. The spokes are turned from a billet as shown at A at the top of the illustration, the successive operation being shown at B in which the spoke has been turned approximately to size on a special turning lathe. The operation is called club turning because of the shape of the stock after it leaves the machine. The way the elliptical section is obtained is by having

movable centers and a cam motion to move the lathe heads in and out with respect to the cutters so as to get the section desired. The next operation is mitering down the big end as shown at C and then passing it over a planer to have the wedged shape end of uniform thickness, as outlined at D. The next step is to turn the tenon at the upper end which fits into the wheel felloe.

The felloes are made by bending special pieces of stock (which has been steamed) by a form of clamp and introducing a spacer between the two ends in order to secure the desired curvature. The bent blanks are kept in the form shown at B for a period of time and placed in drying kilns. After removal from the kiln they are held by a strip S for a time after which the strip is knocked off and the felloes sawed to the proper form. The pieces D are planed on both sides and also finished on the curved surfaces in order to smooth them, followed by an operation to drill for the spokes with a special machine. The next step is to smooth the felloe member carefully on the inside, then to sand paper off the sharp corners between the spoke holes. The felloe strips are then taken to a special machine which cuts the ends with proper relation to the spoke holes so the wheel may be assembled. The last operation is spot facing which is a form of counter boring on the inside of the felloe where the end of the spoke comes in contact with it.

The first stage in assembling the wheel is shown at A in the lower portion of the illustration. Here the spokes are driven into the felloe and when the two halves of the wheel are available they are placed in a special machine which clamps the spokes and the felloe band tightly together. While the wheel is in this machine a dummy hub is put in place and tightly clamped as shown at C. The function of this is to keep the wheel together during the assembly process. When the wheels have been clamped they are taken to an operator who cuts the joints in order to provide for the shrinking of the steel rim. The clamped wheel is taken over to a special table where the rims are placed on them. The rims of steel are heated by a series of gas flames which play upon all portions of a steel rim or band until this has been expanded enough so the wheel can be readily inserted. The rim is dropped over one of the unrimmed wheels as shown at C and placed under a heavy press

which forces the steel rim to its proper position on the wooden felloe. After the rim has been shrunk on, the false hub may be removed as the rim keeps the wheels together. The center is then bored out and a finishing cut taken on both sides of the spokes at the hub. The wheel is then carried to a drill press of the multiple spindle type which makes all of the holes for the brake drum or hub flanges. The final assembly process is to put the hub flanges in place and bolt them up.

A wooden wheel is not subject to damage or depreciation from use unless the car has skidded into a curb or hit some obstacle that will tend to knock the wheel out of true or break some of the spokes. As a rule, broken spokes can only be inserted by a wheelwright or one familiar with the manufacture of wheels. In cases where only one or two spokes are broken it is possible to insert new ones by unbolting the hub flanges and drilling out the broken end of the tenon pin that remains in the felloe. The new spokes, which may be made by hand in an emergency, are easily inserted in place of the damaged ones and the wheel assembly again clamped together between the hub flanges. In some cases, after a car has been used for a time, especially in dry sections of the country, considerable slack or looseness may exist between the hub flanges and spokes and also between the spokes themselves. No trouble will be experienced from this source if a car is washed frequently because the water will prevent the spokes from shrinking away from the hub flanges. Even if the looseness is noticeable, which is a fertile source of squeaking noises coming from the wheels while they are in service, in many cases the spokes may be swollen enough by soaking the wheel well with water to correct the trouble.

A simple method of overcoming this difficulty when the soaking treatment does not correct the fault is shown at Fig. 412. If the work is carefully done a badly racked wheel may be made capable of giving considerably more service. The hub is shown in the sketch with the flange removed to expose the mortised ends of the spokes to view. This may be easily accomplished by removing the nuts from the bolts and prying the hub flange away from the wheel. The lost motion between the spokes can be taken up by driving thin wedges of sheet steel into the open spaces though in some cases