770G and 772G Off-Highway Truck Hydraulic System

Schematic

Hydraulic System (1) Oil from Control Manifold (Parking Brake Release) (2) Raise relief valve (3) Main relief dump spool (4) Oil to brake oil coolers (5) Oil from Control Manifold (Brake Accumulator Charge) (6) Lower relief valve (7) Dual stage signal spool (8) Control Valve (Hoist) (9) Lower solenoid (10) Transmission/Chassis ECM (11) Gear Pump (Hoist) (12) Hoist cylinders (13) Orifice plates (14) Hydraulic Tank (Brake, Brake Cooling, Hoist) (15) Breather filter (16) Brake cooling relief valve(17) Raise solenoid

Location of Components

Location of Components (2) Raise relief valve (6) Lower relief valve (8) Control Valve (Hoist) (9) Lower solenoid (11) Gear Pump (Hoist) (12) Hoist cylinders (14) Hydraulic Tank (Brake, Brake Cooling, Hoist) (17) Raise solenoid (18) Brake Valve (Parking)(19) Control Manifold (Parking Brake Release)

Secondary Brake System

Location of Secondary Brake Control Pedal

(1) Secondary brake control pedal

Secondary brake control pedal (1) is located on the left side of the cab floor. Secondary brake control pedal (1) uses the parking brakes to stop the machine. Secondary brake control pedal (1) should be used to stop the machine if the service brakes do not function properly. Secondary brake control pedal (1) does not lock in any position. As a result, the secondary brake function will be released. The position sensor on the pedal sends a proportional signal to the Brake ECM. The Brake ECM then actuates the Brake Valve (Parking) in order to apply the secondary brakes. No adjustment is necessary on secondary brake control pedal (1) or the position sensor for the pedal. The position sensor calibrates automatically.

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