Cause analysis of walking weakness of Caterpillar 320C excavator

Cause analysis of walking weakness of Caterpillar 320C excavator
1 All actuators are powerless

( 1 ) Operate the control handle. If you do not hear the sound of the engine refueling, you can open the data output of the automatic control system maintenance program ( you can also pull out the pressure relay connector, manipulate the control handle, check the pressure relay with a multimeter, and connect it normally ). Operate the control handle to check whether the pressure relay fails. If it fails, replace it. Otherwise, check the engine speed. If the speed is abnormal, check and repair the engine.

( 2 ) check whether the system has air, if any, exhaust ; 
 
( 3 ) Check whether the oil suction filter is blocked, and replace the filter if blocked ; 
 
( 4 ) Check the pump tubing is unobstructed ;
( 5 ) Check the pilot pressure : connect the 60 bar pressure gauge on the pilot pressure measuring point to see whether the pressure meets the requirements ( the standard is 34.5 bar ). If not, adjust the pilot pressure control valve. If not, check the pilot pressure control valve : whether the valve core is worn ( replaced or repaired ), the adjustment spring ( standard length is 53.8 mm ) is fatigued or broken ( replaced spring ), and whether it is stuck ( remove foreign matter ).

( 6 ) Check the pressure of the safety valve : connect two 600 bar pressure gauges to the pressure measuring port of the two pumps, then jam the crawler and operate the walking pilot handle. If the pressure of the pump is abnormal ( standard 343bar ), adjust the pressure of the main safety valve to the specified value. If the pressure cannot be increased, check and eliminate the main safety valve failure, mainly include : A, the position where the cone surface of the safety valve core is stuck by the foreign body ( remove the foreign body ) ; b, adjust the spring fatigue or broken ( replace the spring ) ; c, the sealing cone of the safety valve is seriously worn and the closing is not strict ( repair or replacement ) ; d, damping hole blockage ( remove blockage ), such as the normal pressure of the pump for the next step ; 
 
( 7 ) Check the shift pressure : if the shift pressure is too high, the flow of the pump will be too small, resulting in slow and weak movement. The pressure gauge of 60 bar can be connected to the shift pressure measuring port, and the maintenance program can be started to see whether the data displayed on the screen is normal and whether it is equal to the reading of the pressure gauge. If it is not normal, it can be adjusted by the maintenance program. If it cannot be adjusted, the cleaning proportional valve can be checked to eliminate the fault of the proportional valve. If the proportional valve is normal and the shift pressure cannot be adjusted, the fault of the electrical system can be eliminated.

( 8 ) Check whether the two reverse flow control tubings are blocked ( or whether the hydraulic piston is stuck ), and remove ( remove stuck ) if blocked ; 
 
( 9 ) Check the flow rate of the pump : the engine speed is 1800rpm, the output pressure is 9800kpa, the flow rate of the pump is 180l / min, the limit of use is 170l / min, if the flow rate is too small, the flow rate of the pump can be adjusted by adjusting the flow adjustment bolt, if it can not meet the requirements, it may be A, the matching surface of the oil distribution plate and the copper cylinder block is worn ( grinding the matching surface ) ; b, compression spring fatigue or broken ( replace the spring ) ; c, the clearance between plunger and hole is too large ( repair or replace plunger and copper cylinder block ) ; d, the pump servo piston is stuck in a small flow position ( remove foreign matter ) ; e, servo valve card ( remove foreign matter ) ; f, servo valve spring fatigue or broken ( replacement ) ;
2 Only walking mechanism is powerless
( 1 ) Operate the walking control handle and listen to the engine sound. If you do not hear the sound of the engine refueling, you can open the data output of the automatic control system maintenance program ( you can also pull out the pressure relay connector, manipulate the walking control handle, check the pressure relay with a multimeter, and connect it normally ). Operate the walking control handle to check whether the pressure relay fails. If it fails, replace it, otherwise check and repair the engine ; 
 
( 2 ) Low oil pressure of walking leader : check the pressure of walking leader, twist the screw plug on the joint of walking pressure switch, connect the pressure gauge of 60bar, and operate the handle of walking leader ( push to the end should be greater than 30bar, part of the push should be about 18bar ). If the valve is abnormal, check, repair or replace the pilot valve, mainly : the stroke is not enough ( adjustment ), the pressure regulating spring is too soft ( replacement ), the stem is stuck or worn ( removal of blockages or repair, replacement ) ; 
 

( 3 ) Check the pressure of the mutual-ejection relief valve : connect the 600 bar pressure gauge to the pressure measuring port of the front and rear pumps, jam the crawler, and operate the walking joystick. The normal pressure should be 368 bar. If the pressure is abnormal, try to adjust the overflow pressure of the mutual-ejection relief valve. If it cannot be adjusted, check the mutual-ejection relief valve. The main check is whether the pressure regulating spring is fatigued ( replaced ) and the sealing cone surface ( ground ). If it is stuck by a foreign body, the foreign body is removed. If the mutual-ejection relief valve is normal and the pressure is not high, the next step is carried out.