320E, 320F, 323E, 323F, 324E, 326F, 329E, 329F and 330F Excavators Tool Control System Caterpillar

Specification

Introduction

The line relief valves are located between each cylinder and the respective control valve. The line relief valve limits the overload pressures that can be created in the implement cylinders. The line relief valves are located on the left side and right side of the main control valve. The line relief valves are accessible from above the main control valve and below the machine after removal of the access plate.

Required Tools

Illustration 1	g01623868
Tooling group "B" 198-4240 Digital Pressure Indicator Gp

Machine Preparation

1. The following procedures must be completed before testing the line relief valves.

   • Set the pilot pressure to the specifications in Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" for the machine.

   • Calibrate the power shift pressure. Refer to Testing and Adjusting, "Solenoid Valve (Proportional Reducing) - Calibrate (Power Shift Pressure)" 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.

2. Position the machine on level ground and stop the engine.
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   Illustration 2	g03602396
   Stop valves for high-pressure oil delivery to the work tool (typical example)

3. 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.

4. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release" for the machine.
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   Illustration 3	g03625057
   Pump compartment (typical example) (1) Pressure tap (delivery pressure for drive pump) (2) Pressure tap (delivery pressure for idler pump)

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   Illustration 4	g06267001
   Pump compartment (typical example) (1) Pressure tap (delivery pressure for drive pump) (2) Pressure tap (delivery pressure for idler pump)

5. Attach both 41,368 kPa (6,000 psi) pressure sensors to pressure tap (1) and pressure tap (2).

Test Procedure

Note: A temporary setting of the main relief valve is required before any line relief valves can be adjusted. Refer to Table 3 for temporary main relief setting for the function being tested.

Note: Pressure values in Table 4 are approximate values. Use a pressure gauge for adjustment.

1. Start the engine.

2. Select a work tool to meet the following conditions.

   • Two-way flow from one pump

   • Variable relief valve pressure set at the default specifications of 40,000 kPa.

   Refer to Testing and Adjusting, "Work Tool - Select" for the Tool Control System.

3. Place the hydraulic activation control lever in the UNLOCKED position.

4. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

5. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

6. Move the joystick for the stick until the stick is at the full STICK OUT position (full retraction of the stick cylinder).

7. Check the main relief valve pressure setting at pressure tap (1) or pressure tap (2). The main relief valve pressure setting should be 35000 ± 500 kPa (5076 ± 73 psi).
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   Illustration 5	g03627277
   Main relief valve (standard) (A) Adjustment screw (L) Locknut

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   Illustration 6	g03627279
   Main relief valve (heavy lift) (A) Adjustment screw (L) Locknut

8. Loosen the locknut. Set the main relief pressure to 37000 ± 500 kPa (5366 ± 73 psi). Tighten the locknut.

   Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

   Note: Always make final pressure adjustments on pressure rise.

9. Verify the temporary main relief pressure setting with a second function. Move the joystick for the boom until the boom is at full BOOM RAISE position (full extension of the boom cylinder). The main relief pressure should be 37000 ± 500 kPa (5366 ± 73 psi).
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   Illustration 7	g03635676
   Line relief valve for extension of the attachment control valves (typical example)

10. Mark the original position of the line relief for the attachment control valve extend.
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    Illustration 8	g02292254
    Control Inputs for attachment control valves extended. (LJ) Left-hand joystick (RJ) Right-hand joystick (A) Thumb wheel (Forward) (A) Switch (FP) Electric foot pedal (A) Pedal (Forward) (FS) Foot switch (A) Foot switch (ON)

11. Operate the control input in the appropriate direction in order to relieve the valve.

    Note: A continuous relief of the valve for more than 10 seconds is not allowed.

12. Check the pressure setting of the line relief for the attachment control valve extend.

13. Loosen the locknut of the extend line relief valve. Turn adjustment screw of the extend line relief valve until the pressure reading at pressure tap (1) is 35000 kPa (5076 psi).

14. Operate the control input in the appropriate direction in order to relieve the valve.

15. Check the pressure setting of the line relief for the attachment control valve extend.

16. Turn the adjustment screw of the extend line relief valve until the pressure reading at pressure tap (1) is 37000 ± 500 kPa (5366 ± 73 psi).

    Note: Always make final pressure adjustments on the pressure rise.

    Note: In order to prevent over setting, the adjustment should be stopped immediately after the pressure becomes within specification.

17. Repeat Step 11 to Step 16 for the following line relief valves:

    • Line relief valve for attachment control valve retract

18. Reset main relief valve pressure setting to the normal operating condition after the completion of the line relief test and adjust. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

Illustration 9	g03635680
Line relief valve for retraction of the attachment control valves (typical example)

Illustration 10	g02292257
Control Inputs for attachment control valve retracted. (LJ) Left-hand joystick (RJ) Right-hand joystick (B) Thumb wheel (Backward) (FP) Electric foot pedal (B) Pedal (Backward)

Adjustment Procedure

Illustration 11	g03626958
Line relief valve (typical example (L) Locknut (A) Adjustment screw

1. Loosen locknut and turn adjustment screw in order to increase or decrease pressure.

   Note: Turn the adjustment screw clockwise in order to increase pressure. Turn adjustment screw counterclockwise in order to decrease pressure.

   Note: Always make final pressure adjustments on the pressure rise.

2. Tighten the locknut to specification once adjustments are complete.