ROLLER GP-DFLG 5364943 - Caterpillar

Illustration 1 g00714342
Brake Control Valve (1) Valve spool (parking brake) (2) Passage (3) Valve spool (service brake) (4) Plunger (5) Flow to service brakes (6) Transmission controls (7) Priority Valve (8) Filter (9) Transmission charge pumpThe brake control valve controls the service brake and parking brake functions. The brake control valve is mounted on the top of the main case of the machine.The parking brake valve is an ON/OFF valve.The service brake valve is a pressure reducing valve.Oil from the transmission charging section of the power train oil pump flows to parking brake valve spool (1) .When the parking brake lever is in the ENGAGED position, oil flow to service brake valve spool (3) is blocked.When the parking brake lever is in the RELEASED position, parking brake valve spool (1) directs oil to passage (2). The oil in passage (2) flows to service brake valve spool (3) .If the service brakes are not applied, plunger (4) holds service brake valve spool (3) open. Oil from passage (2) flows through passages in the valve body into the lines for the service brakes. The oil flows through these lines to the service brakes and the pressure of this oil holds the service brakes in the OPEN position.When plunger (4) is slightly engaged, service brake valve spool (3) applies less force to the spring. This reduces the oil pressure to the service brakes.The reduction in pressure allows the belleville springs to apply more pressure to the plates and the discs in the service brake housing. The result is a reduction in the speed of the machine.When service brake valve spool (3) is completely engaged, less than 70 kPa (10 psi) of pressure is sent to the service brakes and the brakes are completely engaged.After the pressure that is required for the service brakes is reached, the oil from the transmission charging section of the power train oil pump opens priority valve (7) and oil flows to transmission control valve (6).