FENDER AS-FRONT 1179056 - Caterpillar

Illustration 1 g01031967
Rear view of the right side wheel brake assembly
(1) Air purge valve for the service brake
(2) Inlet passage for the axle oil cooling
(3) Air purge valve for the parking brake
(4) Oil passage for the service brake
(5) Test port for the parking brake
(6) Test port for the service brake
(7) Oil passage for the parking brake
Illustration 2 g01031968
Components of a wheel brake assembly
(8) Outer plate
(9) Service brake piston
(10) Parking brake piston
(11) Spring
(12) Duo-Cone seal
(13) Wheel assembly
(14) Friction disc
(15) Housing
(16) Oil chamber
(17) Oil chamber
(18) Guide pin
(19) Oil chamber
(20) Return spring
(21) Anchor
(22) Passage
(23) Spindle The service and parking brakes are located between the axle housing and the final drive.The service and parking brakes are an oil immersed, multiple disc type brake group. Each brake group consists of a service brake piston (9) and a parking brake piston (10). The service brakes are applied by pressure oil and released by springs (20). The parking brakes are engaged by springs (11) and disengaged by pressure oil.Wheel assembly (13) is connected to housing (15) by spindle (22) and two taper roller bearings. Housing (15) and spindle (23) do not turn. Housing (15) is connected to spindle (23). Anchor (21) is connected to housing (15). Plates (8) are splined to housing (15). Plates (8) do not turn. Friction discs (14) are splined to wheel assembly (13). Friction discs (14) turn with wheel assembly (13).Axle oil cooler oil flows into the wheel brake through inlet passage (2), into chamber (16). The axle oil cooler oil cools friction discs (14) and plates (8). The axle oil cooler oil then flows out through passage (22) into the final drive. Axle oil cooler oil then returns to the axle housing through the centre of spindle (23).Air purge valve (3) is used to remove the air from the hydraulic system for the parking brake. Air purge valve (1) is used to remove the air from the hydraulic system for the service brakes.Parking Brake
The parking brake is engaged by springs and disengaged by pressure oil. When the parking brake is engaged, the pressure oil behind parking brake piston (10) flows from passage (17) through the parking brake control valve and returns to the hydraulic tank. With no pressure oil behind parking brake piston (10), the force of springs (11) push on parking brake piston (10). Parking brake piston (10) pushes on service brake piston (9). Service brake piston (9) pushes friction discs (14) and plates (8) together and friction occurs. The friction prevents wheel assembly (13) from rotating.When the parking brake is disengaged, pump pressure is sent to oil passage (7). Oil then flows into oil chamber (17). The pressure oil forces parking brake piston (10) to compress springs (11), until parking brake piston (10) contacts anchor (21). As parking brake piston (10) moves away from service brake piston (9), springs (20) and guide pin (18) move service brake piston (9) away from friction discs (14) and plates (8). Friction discs (14) and plates (8) will not be in contact and the