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WHEELS, RIMS AND TIRES
Wood Wheel Construction-Houk Wire Wheel-Dunlop Wheel–Rudge-Whit
worth 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 TiresThe 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
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 forin. 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 Cand 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 un. bolting 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 when the spokes are very loose hard wood wedges may be driven in. In making the wedges they should be shaped straight with a short taper at the end to facilitate driving them in place. It is said that if made with a taper their full length that they will have a tendency to work out. Before driving the wedges in place they should be covered with a coating of glue and after all the wedges necessary have been inserted the protruding edges can be cut off with a chisel and the ends smoothed down flush with the spokes. Before replacing the hub flange the center of the wheel should be covered with a coat of priming paint. Obviously, the wedges should be as wide as the thickness of the spokes and only sufficiently thick to take up the space existing between the spokes. If a wheel is not very loose, wedges 1, 2, 3, 4, 5, and 6 are driven into place, though in very loose wheels another set of wedges numbered 7, 8, 9, 10, 11 and 12 should be used to fill the re- ;
Fig. 412.—Method of Using Wedges to Take Up
Looseness Between Spokes of Wooden Wheels. maining space. It will be apparent that the bolt holes must be cleared out with a drill after the wedges have been driven in. The final operation is to replace the hub flange and bolt it tightly in position. It will be found advisable to burr over the projecting ends of the bolt after the nuts are screwed down tightly in order to prevent the nuts from backing off. The wheels of some cars are held together by rivets instead of bolts. As the heads of the rivets must be sheared off with a cold chisel to permit removal of the flange, new rivets must be in