VALVE GP-RELIEF 2019350 - Caterpillar

Illustration 1 g03571176
Service brake
Illustration 2 g03571178
View A-A
(1) Piston
(2) Friction Plate
(3) Wear Plate
(4) Reaction Plate
(5) Guide Pin
(6) Dowel
(7) Spring
(8) Sun Gear
(9) Planetary Carrier All four service brakes are located in the axle assemblies. The service brakes are actuated by either the left or the right brake pedal. The service brakes are in both the front axle and in the rear axle.Each service brake consists of the following components: piston (1), friction plates (2), wear plate (3), reaction plate (4), guide pin (5), spring (7), sun gear (8) and planetary carrier (9).Plate (4) is held stationary by dowels (4). The dowels (6) are fastened in the axle housing. The plates for the piston housing are able to slide on the three guide pins (5). The plates do not rotate. Springs (7) keep piston (1) in the RETRACTED position when the piston is not being used.Friction plates (2) has splines on the inside diameter that fit on the splines of sun gear (8). Planetary carrier (9) causes friction plates (2) to rotate at the speed of the planetary carrier (9). Grooves are cut into the faces of friction plates (2). The grooves allow the passage of cooling oil between friction plates (2) and wear plate (3), and between piston (1) and wear plate (3).Cooling oil will flow even when the service brakes are applied. If the groove depths in friction plates (2) are within specifications, cooling oil will constantly flow between wear plate (3) and friction plates (2).Planetary carrier (9) is fastened with splines to the axle shaft. Planetary carrier (9) rotates with the axle shaft.When you push a brake pedal, pressurized oil from the service brake control valve flows through the oil passage in the differential housing. The force of the oil behind piston (1) moves the piston against the force of springs (7).The force of the oil also pushes friction plates (2) against wear plate (3). This causes friction between discs (2) and plate (3). The friction slows down the following components: sun gear (8), axle and the wheels. The machine can then be brought to a complete stop.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 (1) flows through the oil passage . This oil flows to the service brake control valve. The oil then returns to the hydraulic oil tank. With no oil pressure behind piston (1), springs (7) move the piston to the RETRACTED position and the service brakes are released.The service brakes can be actuated by either the left brake pedal or by the right brake pedal. When the transmission neutralizer is disabled, both of the brake pedals apply the service brakes. However, only the left pedal may be used to neutralize the transmission. Neutralize the transmission allows the full engine power to be used in the hydraulic system.If the machine loses power, or if the hydraulic pump fails, the service brakes can still