HANDLE GP-MODULAR 1450874 - Caterpillar

Introduction
The accumulator stores pilot pressure oil for use at the main control valves. During multiple operations, the pilot system will demand more oil in order to maintain valve operation. The accumulator provides pilot pressure oil to the pilot system, when the pilot pump flow is inadequate. Inadequate flow will cause sluggish implement control.Required Tools
Illustration 1 g01089423
Tooling (A)
Illustration 2 g01784963
This tooling group is used to test the pressure in the pilot manifold.
Table 2
Tool Item Qty Part Number Description
A A1 1 8T-0856 Pressure Gauge
(0 to 6,000 kPa (0 to 870 psi))
A2 1 6V-3989 Fitting
A3 2 6V-4143 Quick Connect Coupler
A4 1 177-7860 Hose As
F F1 1 6V-3965 Fitting
F2 1 3J-1907 O-Ring Seal Test Procedure
Preliminary Test
Start the engine. Place the hydraulic lockout lever in the UNLOCKED position.
Position the implements 1 m (3.3 ft) from the ground.
Shut off the engine by turning the start switch to the OFF position. When the engine has stopped, return the start switch to the ON position.
Move the joysticks in order to lower the implements. When the accumulator circuit is functioning properly, there will be enough stored energy for approximately 20 seconds after a power loss to lower the implements to the ground safely.
If the preliminary test fails and the implements are unable to be lowered to the ground safely after a power loss, proceed to test the accumulator circuit. Refer to "Testing the Accumulator (Nitrogen Gas Charge)". Testing the Accumulator (Nitrogen Gas Charge)
Note: Some accumulators do not have a charge pressure port. This type of accumulator cannot be recharged. The accumulator must be replaced. Replacement accumulators are equipped with a charge pressure port.
Illustration 3 g02103574
Cap for charging port on accumulator
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the testing and charging procedure. Note: If the pressure reading is within the specifications of Table 1, continue to test the operation of the check valve within the pilot manifold. Refer to "Testing the Check Valve (Pilot Manifold)".Testing the Check Valve (Pilot Manifold)
Illustration 4 g02104695
Location of the check valve in the pilot manifold
If the check valve does not close properly during a loss of pilot pressure, the accumulator precharge pressure will exhaust before being able to provide lowering of the implements.Note: Make sure that the accumulator has a proper nitrogen gas charge before attempting to test the check valve. An improperly charged accumulator may give indications of a problem with the check valve.
Stop the engine. Release the pressure from the pilot hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release".
Connect a 6000 kPa (800 psi) pressure gauge to port "PSA2" on the pilot manifold. Use tooling group (A) and tooling group (F).
Start the engine and place the hydraulic lockout lever in the UNLOCKED position.
Shut off the engine by turning the start switch to the OFF position. When the engine has stopped, return the start switch to the ON position.
After the power loss, the accumulator will still have pilot system pressure. Use the stopwatch to observe the pilot pressure. The pilot