PLATE 1107691 - Caterpillar

Introduction
The accumulator stores hydraulic oil pressure that can be used to lower the implements when the engine is off. The accumulator is on the pilot manifold.The following procedure will determine if the accumulator for the pilot system is charged to the appropriate pressure.Required Tools
Illustration 1 g02726620
Tooling (B)
Table 2
Tool Item Qty Part Number Description
B B1 1 8T-0856 Pressure Gauge
(0 to 6,000 kPa (0 to 870 psi))
B2 1 6V-3989 Fitting
B3 2 6V-4143 Quick Connect Coupler
B4 1 177-7860 Hose As (10 ft) Test Preparation - Accumulator Leak Down
Move the machine to a smooth horizontal location.
Engage the parking brake.
Lower all the implements.
Stop the engine.
Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.
Illustration 2 g06089004
(1) Accumulator
(2) Implement valve stack
(3) Pressure tap
(4) Pressure tap
(5) Pilot manifold
Attach tooling (B) to pressure tap (3).Test Procedure - Accumulator Pilot Oil Pressure Leak Down
Start the engine. Warm the hydraulic oil to 52.5° 7.5°C (94.5° 13.5°F).
Record the pressure reading on pressure tap (4).
Stop the engine. Turn the key to the ON position but do not start the machine.
With the implement lockout switch in the UNLOCKED position, record the pressure reading at pressure tap (4).
Allow charge pressure to slowly bleed down.Note: The system should maintain pressure greater than 1050 kPa (152 psi) for a minimum of three minutes. If the system drops to the accumulator pre-charge pressure in less than three minutes, the pilot oil system should be checked for excessive leakage.Adjustment Procedure - Pressure Leak Down
There are no adjustments that can be made to reduce pressure leaks in the system. Inspect the components of the charging system to determine the cause of the system leakage.Test Preparation - Accumulator Charge Pressure
Move the machine to a smooth horizontal location.
Engage the parking brake.
Lower all the implements.
Stop the engine.
Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.
Illustration 3 g06089004
(1) Accumulator
(2) Implement valve stack
(3) Pressure tap
(4) Pressure tap
(5) Pilot manifold
Attach tooling (B) to pressure tap (4) on pilot manifold (5).Test Procedure - Accumulator Charge Pressure
Note: Verifying the accumulator charge pressure is only necessary if excessive leakage is discovered in the previous test.
Start the engine. Warm the hydraulic oil to 52.5° 7.5°C (94.5° 13.5°F).
Operate the engine at HIGH IDLE.Note: At the accumulator, the pilot pressure at pressure tap (4) should be 3300 140 kPa (479 20 psi).
Shut off the engine. Turn the key to the ON position. The accumulator charge pressure should remain steady until an implement control is exercised.
With the implement lockout switch in the UNLOCKED position, move the implement control out of the HOLD position in any direction to actuate a function. Return the handle to the hold position between activations of the handle. Quick movement of