CONTROLLER 4567957 - Caterpillar

Illustration 1 g03390440
Parking brake (cross section)
(1) Spring
(2) Brake piston
(3) Separator plate
(4) Friction plate
(5) Barrel
(6) Port
(7) Brake pilot valve
(8) Spring
(9) Passage
(10) Retainer
(11) Orifice
(12) Orifice
(13) Valve
(14) Shaft
(15) Body
(16) Piston chamber
(17) Passage
(18) Passage
(19) Passage Separator plates (3) are splined to motor housing (15). Friction plates (4) are splined to barrel (5).When no pump oil is supplied to the travel motor, brake piston (2) is forced to the left by the force of spring (1). The oil in piston chamber (16) flows through passage (9), orifice (11) and passage (17). The oil flows from orifice (11) to the case drain port of the motor. When brake piston (16) moves to the right, separator plates (3) and friction plates (4) are forced against housing (15) by the force of spring (1). The rotation of barrel (5) and the rotation of shaft (14) stop and the parking brake is engaged.Orifice (11) in valve (7) restricts oil flow from piston chamber (16). The restriction of return oil flow delays the application of the parking brake. The parking brake is delayed in order to give the machine time to stop. Earlier wear and/or damage to the machine could result if the machine stayed in motion.Prior to the operation of the travel motor, a portion of the pressure oil flows through passage (19). Then, the oil flows through passage (18) and pushes open brake pilot valve (7). The oil then flows through passage (9) and flows into piston chamber (16). Brake piston (2) is moved to the left against the force of spring (1). Separator plate (3) and friction plate (4) release which allows barrel (5) and motor shaft (14) to turn.