GEAR-ACCESSORY DRIVE 7W1102 - Caterpillar

Operational Test for the Pilot Oil Accumulator
Table 1
Required Tooling
Tool Qty Part Number Description
A 1 177-7860 Hose Assembly
B 1 8T-0856 Pressure Gauge 4000 kPa (580 psi)
Locate the pressure tap for the pilot pressure.
Install tooling (B) on tooling (A) that has quick disconnect fittings. Install the other end of the hose to the pressure tap for the pilot pressure.
Start the engine and run the engine at HIGH idle. The pressure gauge should read 3450 200 kPa (500 30 psi).
Stop the engine. Turn the start switch to the ON position. Do not start the engine.
Move the implement control levers several times through the full range of travel. This process will relieve any pressure that may be present in the implement hydraulic system. Turn the key start switch to the OFF position. Note: For more information on releasing the hydraulic system pressure, refer to Testing and Adjusting, "System Pressure - Release".
Watch the pressure gauge. Move the control lever or the joystick in order to lower the boom. The pressure will steadily decrease.
When the pressure is approximately 2000 100 kPa (290 15 psi), the pressure will suddenly drop to zero. This action occurs because no oil is left in the accumulator. The final pressure prior to the sudden drop to zero is the approximate pressure of the accumulator charge. Discharging the Accumulator
Ensure that the oil in the hydraulic system is at normal operating temperature. Park the machine on a smooth, level surface.
Install the steering frame lock. Block the wheels. Stop the engine.
With the engine stopped, turn the key start switch in the ON position. Move the implement control levers several times through the full range of travel. This process will relieve any pressure that may be present in the implement hydraulic system. Turn the key start switch to the OFF position. Note: For more information on releasing the hydraulic system pressure, refer to Testing and Adjusting, "System Pressure - Release".
Locate the pilot oil accumulator.
Illustration 2 g01187613
Typical example
Remove protective cap (1) which protects the charging valve of accumulator (2).
Remove the protective cap on the nitrogen charging valve.
Illustration 3 g00282185
(3) Nipple. (4) Coupling assembly. (5) Pressure gauge. (6) Hose assembly. (7) Coupling assembly. (8) Nipple. (9) Valve. (10) Pressure gauge. (11) Regulator assembly. (12) Pressure regulating screw. (13) Chuck for the nitrogen cylinder valve. (14) Valve handle. (15) Nitrogen charging chuck. (16) Hose assembly. (17) Tee.
Identify the correct nitrogen charging chuck. Note: For a nitrogen charging valve with a 0.305 inch -32 THD, use a 1S-8938 Nitrogen Charging Chuck and a 1U-5551 Extension Assembly. For a nitrogen charging valve with a 0.482 inch -26 THD, use a 7S-5106 Nitrogen Charging Chuck and a 7S-5439 Extension Assembly.
Attach hose assembly (16) to nitrogen