How to test and adjust the caterpillar320c excavator turntable safety valve 

 (1) Park the machine on flat ground. 

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 (2) Turn off the engine. 

 (3) Release the pressure of the hydraulic system, refer to the "Pressure Relief of the Hydraulic System" section. 

 (4) Connect a 60000kPa pressure gauge to the pressure measuring joint 2 (Figure 2-3-167). 

 (5) Disconnect the turntable parking brake solenoid valve 29 and the connector 28, as shown in Figure 

2-3-177. 

 (6) Start the engine.  

(7) Set the machine control as follows: set the engine tachometer to 10, and set the AEC switch to OFF.

  See Engine RPM Settings in the Engine Performance Testing section.

  (8) Pull the turntable lever slowly to ensure that the turntable parking brake operates normally. 

 (9) Slowly move the turntable lever to facilitate complete SWING RIGHT operation, and check the 

pressure of the safety valve 25 on the pressure measuring joint 2, as shown in Figure 2-3-178.

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(10) Move the turntable joystick to the NEUTRAL position. 

 (11) The pressure value of the turntable safety valve is (26000 ±980) kPa. If the pressure reading of 

pressure measuring joint 2 is not within the specified range, please adjust the turntable safety valve

. (12) To adjust the turntable safety valve, loosen the lock nut 23. Rotate the adjusting screw plug 22 

until the pressure gauge reading of the pressure measuring joint 2 is (26000 ± 980) kPa. Note: Turn the 

adjustment screw 22 clockwise to increase the pressure; turn the adjustment screw 22 counterclockwise 

to decrease the pressure. Be sure to make final pressure adjustments as pressure increases. 

 (13) Tighten the locking nut 23 to a tightening torque of (117±10) N·m. 

 (14) Slowly turn the turntable lever to perform complete SWING LEFT operation, and check the 

pressure of the safety valve 24 on the pressure measuring joint 2. 

 (15) Return the turntable joystick to the NEUTRAL position. 

 (16) The pressure value of the turntable safety valve is (26000 ±980) kPa. If the pressure reading at 

pressure measuring joint 2 is not within the specified range, adjust the turntable safety valve. 

 (17) To adjust the turntable safety valve, loosen the lock nut 27. Turn adjusting screw plug 26 until the 

pressure gauge reading of pressure measuring joint 2 is (26000 ± 980) kPa. NOTE: Turn adjustment 

screw 26 clockwise to increase pressure; turn adjustment screw 26 counterclockwise to decrease 

pressure. Be sure to make final pressure adjustments as pressure increases. 

 (18) Tighten the locking nut 27 to a tightening torque of (117 ±10) N·m.  

(19) After completing the testing and/or adjustment steps of the turntable safety valve, shut down the

 engine. 

 (20) Release the pressure in the hydraulic system, see the "Pressure Relief of the Hydraulic System" 

section.

  (21) Connect connector 28 to turntable parking brake solenoid valve 29.

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