938G Series II Wheel Loader and IT38G Series II Integrated Toolcarrier Braking System Service Brakes Caterpillar


Service Brakes
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938G Series II Wheel Loader and IT38G Series II <BR>Integrated Toolcarrier Braking System [RENR6074]
POWER TRAIN
AXLE GP
950G Series II Wheel Loader, 962G Series II Wheel Loader and IT62G Series II Integrated Toolcarrier Braking System Service Brake Disc Wear Indicator
938G Series II Wheel Loader and IT38G Series II Integrated Toolcarrier Braking System Service Brakes



Illustration 1g00275276

Service Brakes

(1) Sun gear. (2) Piston. (3) Service brake oil passage. (4) Disc. (5) Plate. (6) Axle. (7) Carrier. (8) Pins (three). (9) Springs (three). (10) Ring gear.

All four service brakes are located in the axle assemblies. The service brakes are actuated by the left brake pedal or by the right brake pedal. There are service brakes in the front axle and in the rear axle.

Note: Some machines may be equipped with only one service brake pedal. However, the service brakes function in the same manner as a machine that is equipped with two service brake pedals.

Each service brake consists of the following components: piston (2), disc (4), plate (5), pins (8) and springs (9) .

Plate (5) and piston (2) are held stationary by three pins (8). The pins are fastened in the differential housing and in the axle housing. The piston and the plate are able to slide on the three pins, but the piston and the plate do not rotate. Springs (9) keep piston (2) in the retracted position when the piston is not being used.

The inside diameter of disc (4) has splines that fit on the splines of sun gear (1). This causes disc (4) to rotate at the speed of the sun gear.

Grooves are cut into the faces of disc (4). The grooves allow the passage of cooling oil even when the service brakes are applied. As the disc rotates, cooling oil will constantly flow between disc (4) and plate (5) and between piston (2) and disc (4) .

Carrier (7) is fastened to axle (6) by splines. The axle turns with the carrier. The gears in carrier (7) rotate between sun gear (1) and stationary ring gear (10) .

When you push a brake pedal, pressurized oil from the service brake control valve flows through oil passage (3) in the differential housing. The force of the oil behind piston (2) moves the piston against the force of springs (9) .

The force of the oil also pushes disc (4) against plate (5). This causes friction between disc (4) and piston (2) and between disc (4) and plate (5). The friction causes sun gear (1), axle (6), carrier (7) and the wheels to turn more slowly.

The heat that is created from the friction of the service brakes is removed by the oil that is in the axle housings.

When the brake pedal is released, the oil behind piston (2) flows through oil passage (3). This oil flows to the service brake control valve. The oil then returns to the hydraulic oil tank. With no oil pressure behind piston (2), springs (9) move the piston to the retracted position and the service brakes are released.

The service brakes can be actuated by the left brake pedal or by the right brake pedal. This is also true for the function of the transmission neutralizer. When the transmission neutralizer lockout switch is moved to the UNLOCKED position, both of the brake pedals will apply the service brakes. At the same time, the pedals will disengage the output of the transmission. This allows the full engine power to be used in the hydraulic system.

If the machine loses power or the hydraulic pump fails, the service brakes can still be applied. The pressure in the brake accumulators allows several applications of the brake pedals so that the machine can be slowed enough to engage the parking brake.

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