COIL A 1050039 - Caterpillar

Illustration 1 g06218485
Relief valve (typical example)
(L) Locknut
(A) Adjustment screwRequired Tools
Illustration 2 g01623868
Tooling group "B"
198-4240 Digital Pressure Indicator Gp
Table 2
Tool Item Part Number Description Qty
B 198-4240 Digital Pressure Indicator Gp
B1 198-4234 Indicator 1
B2 198-4238 Pressure Sensor 34,450 kPa (5,000 psi) 1
B3 198-4236 Extension Cable 1 Machine Preparation
The following procedures must be completed before performing the calibration.
Set the pilot pressure to the specifications in Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" for the machine.
Calibrate the attachment valves. Refer to Testing and Adjusting, "Solenoid Valve (Proportional Reducing) - Calibrate (Attachment Valves)" for the Tool Control System.
Calibrate the flow limit valves. Refer to Testing and Adjusting, "Solenoid Valve (Proportional Reducing) - Calibrate (Flow Limit Valves)" for the Tool Control System.
Position the machine on level ground and stop the engine.
Illustration 3 g06217670
Stop valves for high-pressure oil delivery to the work tool (typical example)
Close the stop valves that are mounted on each side of the stick in order to prevent oil flow to the work tool during this procedure.
Disconnect the medium pressure lines for tool rotation and install the shipping plugs on the medium pressure lines. This action will prevent oil flow to the work tool for rotation during this procedure and allow for the valve to relief.
Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release"
for the machine.
Illustration 4 g06263397
Medium pressure control valve
(1) Pressure tap (delivery pressure for the auxiliary pump)
Attach a 34,450 kPa (5,000 psi) pressure sensor to pressure tap (1).Test Procedure
Start the engine.
Select a work tool for tool rotation.Refer to Testing and Adjusting, "Work Tool - Select" for the Tool Control System.
Place the machine controls at the following settings: engine speed dial "7" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.
Increase the hydraulic oil temperature to 55° 5°C (131° 9°F).
Illustration 5 g03649861
Control Inputs for extension and retraction of the attachment valve for medium pressure
(LJ) Left-hand joystick
(RJ) Right-hand joystick
(C) Thumb wheel (Forward) - "Attachment Valve Extend"
(D) Thumb wheel (Backward) - "Attachment Valve Retract"
Operate the control input to extend and retract the attachment valve.Note: A continuous relief of the valve for more than 10 seconds is not allowed.
Check the main relief valve pressure setting at pressure tap (1) for both directions of flow. Refer to Table 1 for the pressure specifications of the main relief valve.
Return the joystick to the NEUTRAL position.Adjustment Procedure
Main Relief Valve
Illustration 6 g06263398
Main relief valve for attachment control valve
(2) Main relief valve
To adjust the main relief valve pressure setting, operate the control input for extension of the attachment control valve to the FULL position and hold. Refer to Illustration 5 for the control input.
Check the pressure reading at pressure tap (1).
Return the control