312F and 313F Excavator Machine Systems Accumulator (Pilot) Caterpillar

Accumulator (Pilot)
312F and 313F Excavator Machine Systems [M0065824]

Illustration 1g03506187
(1) Accumulator
(2) Pilot oil manifold

The 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 pilot pump. Accumulator (1) will provide pilot pressure 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 2g02513157
(1) Accumulator
(2) Pilot oil manifold
(3) Gas chamber
(4) Bladder
(5) Vessel
(6) Pressure oil chamber
(7) Passage
(8) Inlet port (pilot oil manifold)
(9) Passage
(10) Inlet port (accumulator)
(11) Passage
(12) Passage
(13) Check valve

Pilot oil from the pilot filter enters inlet port (8) of pilot oil manifold (2). Pilot oil flows through passage (9) and opens check valve (13). Pilot oil now flows through passages (7) and (12) to the pilot control valves (joysticks and travel levers/pedals).

The pilot oil also flows through passage (11) into inlet port (10), and then into pressure oil chamber (6). The pilot oil acts against bladder (4) and the nitrogen gas in gas chamber (3) is compressed. Check valve (13) prevents a backflow of the stored oil in the accumulator. The stored oil is used for solely operating the stems of the main control valve.

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