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OVERLAND BRAKE ADJUSTMENT
Fig. 408.—Showing Methods of Brake Adjustment.
lever to which the rod is connected and a slotted actuating member pinned to the shaft employed in operating the brakes. It is merely necessary to rock the member over so that the brake parts will be nearly in engagement with the brake lever or pedal fully released and then to maintain adjustment by screwing the operating lever
tightly against the actuating member with the clamping bolt. Sufficient range of adjustment is provided to take care of all brake slippage other than that caused by worn brake lining. This method of adjustment is clearly shown at Fig. 408, D.
Expanding brakes are harder to fix than constricting brakes especially if they are of the solid shoe form and not provided with frictional material. The first step in examining the internal brake is to remove the wheel which is done with a wheel puller as shown at Fig. 409, A, if the rear construction is of the semi- or threequarter floating type. The full floating wheels may be removed as shown at Fig. 398. When the brake shoes are of the solid cast form an adjustment for depreciation may be made, as shown at Fig. 409, D, providing some of the wear is at the point where the cams act to spread the brake shoes apart. It is possible to put a thin piece of hardened steel on the worn end of the shoe by using dowel pins or flush headed screws. This spreads the brake shoes out slightly, the amount of spreading, of course, depending upon the thickness of the applied pieces and makes it possible to bring the shoes into positive engagement with the brake drums with but small movement of the expanding cams. If the brake shoes themselves are worn and it is not easy to secure new ones, the surfaces may be restored to efficiency by the application of thin sheet brass or steel, which material is firmly held in place by rivets and which has the effect of restoring the worn segment or shoe to its original contour. When pieces are applied to the brake shoes care should be taken in refitting the wheels that the shoes do not bind against the drum when the brake leverage is released. Any high spots existing must be smoothed off with a file in order not to heat up the brake drum through useless friction when the car is in operation.
A typical brake assembly is shown at Fig. 409, D. This is used on some models of the Cadillac car and consists of an internal expanding band and an external constricting one. Adjustment of the service brakes is made by turning the screw S which is on the back of the brake carrier until the part of the band opposite it is brought as close as possible to the brake drum without touching it. Next adjust the nuts T on the eye bolt until the lower half of the band lining just clears the drum. The nut V on the upper end
of the eye bolt is so adjusted as to bring the lever W to the position shown in drawing when the brake is applied. With the brake released the clearance between the lining and the drum should not be over 132-inch, and if more clearance exists it may be reduced by the set screw X in the rocker lever Z.
The internal brake is constructed to be adjusted for clearance between the internal band and the drum without removing the wheels. Jack up the axle so the wheel will clear the ground to permit revolving it by hand. A cover A will be found on the brake drum which can be removed by unscrewing the lock nut B and turning the bolt to the left about a quarter turn until the clamping bar D is released. Next rotate the wheel until the opening registers with the adjusting screw E carried at the back part of the brake band or at the point opposite the expanding toggle
mechanism. Turn the screw E until the part of the brake lining opposite it is brought as close to the inner surface of the brake drum as possible without touching it. Turn the wheel until access is obtained to the six locking screws N and loosen these. This is clone by bringing the opening in the brake drum opposite each screw in turn and turning these with a suitable socket wrench. Then turn the two adjusting screws F F which have right hand threads on one end and left on the other until the center of the pin G stands about three-quarters of an inch back of an im
и aginary vertical line drawn through the centers of the two pins H H when the brake is applied. With the
BRAKE LINING RIVET SET brake released adjust
BRAKE the screw I in the lever
BAND J and the stop screws K K until the lower and upper parts of the
ANVIL brake band lining clear the drum by about 132-inch. The three coil springs M should
RIVET have sufficient tension HEADS to hold the brake band sideways and against the stop screws K K so it will not rattle. It
Fig. 410.—Simple Fixture to Facilitate Rivetis important that the
ing Brake Lining to Steel Brake Bands. sgrews M be locked after completing the work, also that the cover in the opening of the brake drum be replaced and fastened securely.
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 38-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.