VALVE 0874742 - Caterpillar

Main Control Valve Accumulator
Illustration 1 g06198761
(1) Accumulator
(2) Upper pilot oil manifoldThe accumulator stores pilot pressure oil for use at the main control valve. During some operations, the pilot system needs more oil because there is insufficient flow from the pumps. Accumulator (1) provides pressurized pilot oil to the pilot system when the pilot pump flow is inadequate. Insufficient supply of pilot oil flow to the pilot system may be caused by the following two reasons:
Implements are lowered while the engine is stopped and oil supply to the main control valve is stopped
Combined operations
Illustration 2 g06199181
Accumulator
(1) Accumulator
(2) Upper pilot oil manifold
(3) Gas chamber
(4) Bladder
(5) Pressure oil chamber
(6) PassagePilot oil flows through passage (6) of pilot oil manifold (2). Then the oil flows into pressure oil chamber (5). The pilot oil acts against bladder (4) and the nitrogen gas in gas chamber (3) is compressed.Pump Actuator Accumulator
Illustration 3 g06281314
(1) Main control valve
(2) Check valve
(3) Accumulator
(4) Pump actuator
Illustration 4 g06281388
(1) Main control valve
(2) Check valve
(3) Accumulator
(4) Pump actuatorThe accumulator that supplies the pump actuators is located below the main control valve. Pilot oil flows from main control valve (1) through check valve (2) into accumulator (3). Oil simultaneously flows to the pump solenoids (4). The pump solenoids, when activated, supply pilot oil to the pump actuators to upstroke the pump. The oil stored in the accumulator ensures that sufficient oil will always be available to the actuators to stroke the pump. Check valve (2) ensures that oil from this accumulator will only be supplied to the pumps.