TRANSMISSION AR 4420651 - Caterpillar

High Pressure Stall Check
Table 3
Required Tools    
Tool     Part Number     Part Description     Qty    
A     8T-0860     Pressure Gauge     1    
6V-3989 Test fitting     1    
177-7861 Hose     1    
6V-4143 Coupler     2    
Before you check the high pressure stall, ensure that the signal relief valve is adjusted correctly. Refer to Signal Relief Valve Check. If the valve is adjusted correctly, proceed to the next step.
Lower the boom and retract the boom. Ensure that the frame is level.
Stop the engine. Move the steering wheel from left to right. This procedure helps purge pressure from the hydraulic system.
Connect Tooling (A) to test fitting (3) for the pump outlet pressure.
Start the engine and operate the engine at low idle. Move the joystick control to BOOM LOWER in order to stall the pump. The output pressure for the pump at test fitting (3) should be 24976 516 kPa (3625 75 psi). This is the high pressure stall reading. If the pressure is not within the specification, adjust the pressure. Refer to the High Pressure Stall Check.
If the pressure is within the specification, remove Tooling (A) .Margin Pressure Check
Table 4
Required Tools    
Tool     Part Number     Part Description     Qty    
A     8T-0860     Pressure Gauge     2    
6V-3989 Test fitting     2    
177-7861 Hose     2    
6V-4143 Coupler     4    
Before you check margin pressure, ensure that the signal relief valve is adjusted correctly. Refer to Signal Relief Valve Check. If the valve is adjusted correctly, proceed to the next step.
Lower the boom and retract the boom. Ensure that the frame is level.
Stop the engine. Move the steering wheel from left to right. This procedure helps purge pressure from the hydraulic system.
Divide Tooling (A) into two separate gauge assemblies. Install a pressure gauge on test fitting (3) and on test fitting (4) .
Start the engine and operate the engine at low idle. Rotate the steering for the full distance of travel. Hold the steering wheel in this position in order to stall the pump. Subtract the pressure at test fitting (4) from test fitting (3). The difference in pressure should be 2760 173 kPa (400 25 psi). This is the margin pressure. If the pressure is out of specification, adjust the margin pressure. Refer to the Margin Pressure Check.
If the pressure is within the specification, remove Tooling (A) .Low Pressure Standby - Adjust
Illustration 3 g00679929
(10) Cover (11) Adjusting screw (12) LocknutLow pressure standby is controlled by the setting of the flow compensator spool.
Remove cover (10). Loosen locknut (12). Turn adjusting screw (11) clockwise in order to increase the standby setting. Turn the screw counterclockwise in order to decrease the pressure setting.
Do not turn adjusting screw (11) more than a half turn at a time.
Hold adjusting screw (11) in place while you tighten locknut (12) .
Install cover (10) .
Recheck the pressure setting. Refer to the Low Pressure Standby