320E RR Excavator Hydraulic System Caterpillar


Relief Valve (Crossover) - Test and Adjust

Usage:

320E RR LHN

Specification

Table 1
"Relief Valve (Crossover) - Test and Adjust"    
Item     Direction     Machine Settings     Specification     Actual    
Left Travel     Forward     Engine speed dial "10"
AEC switch OFF    
37000 ± 500 kPa (5366 ± 73 psi)        
Reverse Engine speed dial "10"
AEC switch OFF    

37000 ± 500 kPa (5366 ± 73 psi)    
   
Right Travel     Forward     Engine speed dial "10"
AEC switch OFF    

37000 ± 500 kPa (5366 ± 73 psi)    
   
Reverse Engine speed dial "10"
AEC switch OFF    

37000 ± 500 kPa (5366 ± 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 group "A"

198-4240 Digital Pressure Indicator Gp




Illustration 2g03261789

(D) 418-3611 (Track Block)

Table 2
Tool     Item     Qty     Part Number     Description    
A         198-4240     Digital Pressure Indicator Gp    
    A1     1     198-4234     Indicator    
A2 2     198-4239     Pressure Sensor
41,368 kPa (6,000 psi)    
A3 2     198-4236     Extension Cable    
D     1     418-3611     Track Block    

Machine Preparation

  1. Position the machine on level ground.

  1. Stop the engine.

  1. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release".



    Illustration 3g02640916

    Pump compartment

    (1) Pressure tap (delivery pressure for drive pump)

    (2) Pressure tap (delivery pressure for idler pump)

    (3) Pressure tap (power shift pressure)

  1. 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 left travel motor.

  1. 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 right 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    
37000 ± 500 kPa (5366 ± 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    
3050 kPa (440 psi)    

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




Illustration 4g02240859

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.

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

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

  1. 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.

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

  1. Check the main relief setting pressure setting at pressure tap (1) and pressure tap (2) . The pressure setting should be 35000 + 500 - 1000 kPa (5076 + 73 - 145 psi).

  1. Return the joystick to the NEUTRAL position.



    Illustration 5g02102305

    Main relief valve (standard)

    (A) Adjustment screw

    (L) Locknut




    Illustration 6g02102306

    Main relief valve (heavy lift)

    (A) Adjustment screw

    (L) Locknut

  1. Loosen the locknut. Set the temporary 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.

  1. 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).



    Illustration 7g03261818

    Sprocket (left travel)

    (D) Track block

    (4) Sprocket

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

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

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

  1. 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 (1) is 35000 kPa (5076 psi).

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

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

  1. 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 (1) is 37000 ± 500 kPa (5366 ± 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.

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

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

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

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

  1. 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 (1) is 35000 kPa (5076 psi).

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

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

  1. 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 (1) is 37000 ± 500 kPa (5366 ± 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.

  1. 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.

  1. 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.

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

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