320 GC, 320 and 323 Excavator Machine Systems Caterpillar

Specification

Introduction

The crossover relief valves are located on the travel counterbalance valves. The following procedure will determine if the crossover relief valves are out of adjustment.

Required Tools

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

Illustration 2	g03261789
(D) 418-3611 (Track Block)

Machine Preparation

1. Position the machine on level ground.

2. Stop the engine.

3. Release the pressure in the hydraulic system. Refer to Operation and Maintenance Manual, "System Pressure Release".
   Show/hide table

   Illustration 3	g06180512
   Pump compartment (1) Pressure tap (delivery pressure for pump 1) (2) Pressure tap (delivery pressure for pump 2)

4. Connect a 41,368 kPa (6,000 psi) pressure sensor to pressure tap (1). Use this pressure sensor to monitor the crossover relief valve pressure setting of the right travel motor.

5. Connect a 41,368 kPa (6,000 psi) pressure sensor to pressure tap (2). Use this pressure sensor to monitor the crossover relief valve pressure setting of the left travel motor.

Test Procedure

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

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

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

Illustration 4	g06375692
Travel brake valve (left side) (5) Locknut (6) Adjustment screw (7) Crossover relief valve (forward left travel) (8) Crossover relief valve (reverse left travel) (9) Locknut (10) Adjustment screw

1. Start the engine.

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

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

4. 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.

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

6. Check the main relief setting pressure setting at pressure tap (1) and pressure tap (2). The pressure setting should be 35000 + 500 - 2000 kPa (5076 + 73 - 290 psi).

7. Return the joystick to the NEUTRAL position.
   Show/hide table

   Illustration 5	g06195051
   Main relief valve (standard) (A) Adjustment screw (L) Locknut

   Show/hide table

   Illustration 6	g06195116
   Main relief valve (heavy lift) (A) Adjustment screw (L) Locknut

8. Loosen the locknut. Set the temporary main relief pressure to 37500 ± 1500 kPa (5439 ± 218 psi). Turn the adjustment screw clockwise to increase the pressure. Turn the adjustment screw counterclockwise to decrease the pressure. Tighten the locknut.

   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 37500 ± 1500 kPa (5439 ± 218 psi).
   Show/hide table

   Illustration 7	g06196239
   Sprocket (left forward travel) (D) Track block (4) Sprocket

10. Place track block (D) in sprocket (4) to block forward left travel.

11. Slowly move the left travel control lever to full FORWARD position.

12. Check the pressure setting of the left forward travel crossover relief.

13. Loosen the locknut of the left forward travel crossover relief valve. Turn adjustment screw of the left forward travel crossover relief valve until the pressure reading at pressure tap (2) is 35000 kPa (5076 psi).

14. Slowly move the left travel control lever to full FORWARD position.

15. Check the pressure setting of the left forward travel crossover relief.

16. Loosen the locknut of the left forward travel crossover relief valve. Turn adjustment screw of the left forward travel crossover relief valve until the pressure reading at pressure tap (2) is 37500 ± 1500 kPa (5439 ± 218 psi).

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

    Note: Always make final pressure adjustments on pressure rise.

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

17. Remove track block (D) from sprocket (4).

18. Place track block (D) in sprocket to block reverse left travel.

19. Slowly move the left travel control lever to full REVERSE position.

20. Check the pressure setting of the left reverse travel crossover relief.

21. Loosen the locknut of the left reverse travel crossover relief valve. Turn adjustment screw of the left reverse travel crossover relief valve until the pressure reading at pressure tap (2) is 35000 kPa (5076 psi).

22. Slowly move the left travel control lever to full REVERSE position.

23. Check the pressure setting of the left reverse travel crossover relief.

24. Loosen the locknut of the left reverse travel crossover relief valve. Turn adjustment screw of the left reverse travel crossover relief valve until the pressure reading at pressure tap (2) is 37500 ± 1500 kPa (5439 ± 218 psi).

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

    Note: Always make final pressure adjustments on pressure rise.

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

25. To adjust the crossover relief valves on the right travel motor, place the track block (D) in the sprocket for right travel. Use the pressure tap (1) to monitor the crossover relief valve pressure settings for the right travel motor.

26. Return the main relief valve pressure to the specified setting after crossover relief valve pressure setting is attained. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

Adjustment Procedure

Illustration 8	g03328200
Crossover relief valve (A) Adjustment screw (L) Locknut

1. Loosen locknut and turn the adjustment screw clockwise to increase pressure. Turn adjustment screw counterclockwise to decrease pressure.

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

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