PUMP GP-GEAR 5R4477 - Caterpillar

Introduction
The following procedure is used in order to test the pressure of the transmission accumulators.
When testing and adjusting the transmission and power train, move the machine to an area clear of obstructions, with safe exhaust ventilation for the exhausts. Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the transmission and power train.
Machine Preparation
Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the work tools to the ground.
Allow only one operator on the machine. Keep all personnel away from the machine or in the view of the operator.
Engage the parking brake.
Place the steering frame lock in the LOCKED position.ReferenceFor more information about preparing the machine for troubleshooting, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.Required Tools
Table 1
Required Tools    
Part Number     Description     Quantity    
177-7860     Hose assembly     1    
8T-0856     Pressure Gauge     1    Test Procedure
Illustration 1 g03166178
Charge pressure tap port
Install an 8T-0856 Pressure Gauge 4000 kPa (580 psi) on a 177-7860 Hose Assembly that has quick disconnect fittings. Install the other end of the hose to the pressure tap (1) for the charge pressure.
Start the engine. Run the machine until the machine has reached a temperature no less than 70° 10°C (158° 18°F)
Switch the engine to OFF. Attach a 0 to 40 bar gauge to charge pressure tap port (1) .
Start the engine. Wait for systems to stabilize.
Switch the engine to OFF
Observe the pressure on the pressure gauge. The pressure will slowly drop until the accumulators discharge then the pressure will drop rapidly. Record the pressure at the point where the pressure drops rapidly.
Repeat the above process for five times. Record the average pressure where the pressure drops rapidly.
If the accelerated pressure drop starts at a pressure higher than 10 bar, no service is needed.
If the accelerated pressure drop starts at a pressure lower than 10 bar, both accumulators should be charged to 17 1 bar (246 14 psi). Discharge the Accumulator
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the discharging procedure.Nitrogen Charging Procedure
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the charging procedure.