PISTON 1265632 - Caterpillar

Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine.To prevent personal injury or death, perform the following:Park the machine on a smooth, level surface.Lower the work tool to the ground and engage the parking brake.Stop the engine and remove the key.Block the wheels and install the steering frame lock.
The pilot relief valve is located on the front side of the hydraulic tank.
Table 1
Required Tools    
Tool     Part Number     Part Description     Qty    
A     Test Gauge Hose    
6V-4143 Coupler (1)     1    
177-7860 Hose Assembly (1)     1    
8T-4188 Union Adapter (1)     1    
6V-3966 Fitting (1)     1    
B     Test Gauge    
8T-0855 Pressure Gauge (1) (2)     1    
6V-4144 Coupler (1)     1    
( 1 ) Part of 4C-4892 Hydraulic Test Fitting Gp
( 2 ) The 198-4240 Digital Pressure Indicator is also available.Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.
Illustration 1 g02031253
Pilot Relief Valve (1) Locknut. (2) Adjustment screw. (3) Pressure tap.
Attach test gauge (B) to test gauge hose (A) . Attach test gauge hose (A) to pressure tap (3) on the pilot relief valve.
Connect the steering frame lock.
Engage the parking brake.
Shift the transmission to neutral.
Start the engine. Warm the hydraulic oil to a normal operating temperature of approximately 49 to 65°C (120 to 150°F).
Run the engine at low idle. Observe the pressure gauge.The pilot oil pressure should be 3500 100 kPa (507 15 psi).Note: If the machine is equipped with a Custom Product Coal Scoop, the pilot pressure should be 2413 103 kPa (350 15 psi)
Loosen locknut (1) .
Turn adjustment screw (2) clockwise in order to increase the pilot pressure.Turn adjustment screw (2) counterclockwise in order to decrease the pilot pressure.
Tighten locknut (1) .
Verify that the pilot pressure is at 3500 100 kPa (507 15 psi). If the pilot pressure is incorrect repeat steps 7 through 9.Note: If the machine is equipped with a Custom Product Coal Scoop, the pilot pressure should be 2413 103 kPa (350 15 psi)
Once the pressure adjustment is complete, stop the engine and remove test gauge hose (A) from the machine.