HOPPER GP 5088334 - Caterpillar

Illustration 1 g01333260
(1) Service brake pedal (2) Brake control valve (3) RodDisengaged Position
Illustration 2 g02362576
View from bottom of the machineService brake pedal in the DISENGAGED position (4) Piston (5) Tank port (6) Outlet to left service brakes (7) Passage (9) Cavity (10) Lower valve spool (11) Tank port (12) Outlet to right service brakes (13 ) Cavity (14) Spring (15) Supply for the right brakes (16) Lower valve spool passage (17) Passage (18) Upper valve spool passage (19) Supply for the left brakes (20) Upper valve spool (21) Spacer (22) Ball (23) Retainer (24) Spring (25) Spring (26) Spring (27) Retainer (28) SpringWhen the service brake pedal is in the disengaged position, the right and the left service brakes are drained to the tank. Oil flows from the service brakes through outlets (6) and (12) . The oil flows through passages (7) and (17) into the tank return ports (5) and (11) .Partially Engaged Position
Illustration 3 g02362576
View from bottom of the machineService brake pedal in the DISENGAGED position (4) Piston (5) Tank port (6) Outlet to left service brakes (7) Passage (9) Cavity (10) Lower valve spool (11) Tank port (12) Outlet to right service brakes (13 ) Cavity (14) Spring (15) Supply for the right brakes (16) Lower valve spool passage (17) Passage (18) Upper valve spool passage (19) Supply for the left brakes (20) Upper valve spool (21) Spacer (22) Ball (23) Retainer (24) Spring (25) Spring (26) Spring (27) Retainer (28) SpringWhen the brake pedal is depressed, the rod on the pedal assembly pushes piston (4) downward. Piston (4) applies a force on springs (26) , (25) and (24) . The force of springs (26) , (25) and (24) moves retainer (23) and ball (22) . Movement of retainer (23) and ball (22) causes upper valve spool (20) to move away from the seat in spacer (21) .The movement of upper valve spool (20) causes the movement of retainer (27) and lower valve spool (10) . This movement also causes the compression of spring (28) and spring (14) . Spring (28) assists in moving spool (10) . When valve spools (20) and (10) move, the flow path to the tank through the tank return ports (5) and (11) is blocked.This blockage causes pressurized oil from the supply ports (19) and (15) to flow through passages (7) , (18) , (17) and (16) . The oil then flows through passages (6) and (12) in order to engage the service brakes. At the same time, pressurized oil flows through passages (18) and (16) and into cavities (9) and (13) . The oil pressure at the service brakes has the same pressure as the oil in cavities (9) and (13) .Oil pressure in cavity (13) and the force of spring (14) act to balance lower valve spool (10) against the force of the pressure in cavity (9) . In the same manner, pressure in cavity (9) creates a force against the bottom of upper valve spool (20) . The upper valve