How to Solve Caterpillar 320D Hydraulic Excavator Move Slowly Trouble

Here is a real repair case from my blog reader,he share it to me and i re-edit it for share it.His Caterpillar 320D is hardly to operate,it move slowly when operating.Even with free load,it also need more than 10+ seconds to turn around.


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Before Repairing,here ask some question for the problem:

Question 1:Does your Caterpillar 320D engine rotate speed correctly during full load.

Answer 1:Yes,the engine rotate speed is correct,when it with full load.


Question 2:Is the engine smog color looked correctly when it will full load?

Answer 2:Yes,it is heath


Caterpillar 320D Move Slowly Diagnostics:

1.Caterpillar 320D excavator can work with 3 modes:Elaborate mode,common mode and heavy load mode.The 3 work modes work related load:75%,90% and 100%.If the CAT 320D is set under elaborate mode,maybe cause move slowly.(Customer check it work on heavy load mode)


2.Because the engine rotate speed and engine smog are correctly,so the engine is work fine.It maybe the hydraulic system get trouble.

1) Pilot system control oil line with low pressure

The pilot pump provides pressure oil for the pilot system called main control oil line,it can make excavator do related motion.If the pilot system fails and the pilot system pressure is too low,it will cause pilot oil can not control the main control valve or the main control valve spool travel will be shortly,so it will make excavator move slowly.

2) Main pump with low pressure

3) Hydraulic oil line is blocked or hydraulic filter air-logged.


Caterpillar 320D Move Slowly Repair:

1.Check hydraulic oil,it is normal

2.Measure the pressure of the reducing valve is 10kg/cm2,and the inner filter was blocked

3.The hydraulic oil tank was duty and there is a lot of impurities.

4.Pilot pump work fine



Clean the hydraulic system 3 time and replace the hydraulic oil and filter.

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