349F and 352F Excavators Hydraulic System Relief Valve (Crossover) - Test and Adjust Caterpillar


Relief Valve (Crossover) - Test and Adjust
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1.1. Specification
2.1. Introduction
3.1. Required Tools
4.1. Machine Preparation
5.1. Test Procedure
6.1. Adjustment Procedure

Specification

Table 1
"Relief Valve (Crossover) - Test and Adjust" 
Item  Direction  Machine Settings  Specification  Actual 
Left Travel  Forward  Speed Dial "10"
AEC switch OFF 
38200 ± 500 kPa (5541 ± 73 psi)   
Reverse Speed Dial "10"
AEC switch OFF 
38200 ± 500 kPa (5541 ± 73 psi)   
Right Travel  Forward  Speed Dial "10"
AEC switch OFF 
38200 ± 500 kPa (5541 ± 73 psi)   
Reverse Speed Dial "10"
AEC switch OFF 
38200 ± 500 kPa (5541 ± 73 psi)   

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 1g02571852
Tooling (A) 198-4240 Digital Pressure Indicator Gp


Illustration 2g03261789

Table 2
Tool  Item  Qty  Part Number  Description 
  198-4240  Digital Pressure Indicator Gp 
  A1  198-4234  Indicator 
A2 198-4239  Pressure Sensor 41,368 kPa (6,000 psi) 
A3 198-4236  Extension Cable 
418-3612  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 Testing and Adjusting, "System Pressure - Release".


    Illustration 3g02143242
    Pump compartment
    (1) Pressure tap (delivery pressure for drive pump)
    (2) Pressure tap (delivery pressure for idler pump)
    (3) Pressure tap (power shift pressure)

  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.

Table 3
Function  Temporary Main Relief Setting 
Left Travel Forward and Reverse  38200 ± 500 kPa (5541 ± 73 psi) 
Right Travel Forward and Reverse 

Table 4
Relief Valve  Pressure Change With One Turn Of Adjustment Screw 
Main relief valve  14400 kPa (2100 psi) 
Crossover relief valves  13340 kPa (1925 psi) 

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



Illustration 4g02144721
Travel brake valve (left side)
(5) Adjustment screw
(6) Locknut
(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. Set the engine speed dial to position "10" and AEC switch "OFF".

  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 kPa (5076 ± 73 psi).

  7. Return the joystick to the NEUTRAL position.


    Illustration 5g02142898
    Main relief valve (standard)
    (A) Adjustment screw
    (L) Locknut


    Illustration 6g02143255
    Main relief valve (heavy lift)
    (A) Adjustment screw
    (L) Locknut

  8. Loosen the locknut. Set the temporary main relief pressure to 38200 ± 500 kPa (5541 ± 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 38200 ± 500 kPa (5541 ± 73 psi).


    Illustration 7g03137183
    Sprocket (forward left travel)
    (D) Track Block
    (4) Sprocket

  10. Place track block (D) in sprocket (4) in order to block forward left travel. Refer to Illustration 7.

  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 38200 ± 500 kPa (5541 ± 73 psi).

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

    Note: In order 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 in order 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 38200 ± 500 kPa (5541 ± 73 psi).

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

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

  25. In order 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) in order 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 8g03328200
Crossover relief valve
(A) Adjustment screw
(L) Locknut

  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 all adjustments are complete.

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