Failure Analysis and Solutions of Hydraulic Pump Unit and Oil Cylinder 

Ⅰ. Failure analysis of hydraulic pumps unit and oil cylinder and its 

diagnose in use

1、Failure：While running, hydraulic pump system and hydraulic elements lose 

regular function.

2、Diagnose in use:

（1）Inquiry: Whether it is a sudden failure, gradual failure or after 

reorganization failure.

（2）Vision diagnosis: Whether hydraulic oil in tank has bubble or color 

changing; observe the sealing section and find out whether it has oil 

leaking in pipe joint and other joint surface; observe whether the gauge 

hand has the failure of wobble, drop-off and pressure regulating fails to 

come up. 

Acoustic diagnose: High-pitched shrill whistlers means air intake, while, 

the cavitations’ noise could be oil filter blocking, low oil level or too 

much water in hydraulic oil.

（4）Olfactory diagnose: Abnormal smell can judge whether the electronic 

elements has Insulation broken circuit, pay attention to emulsification bad 

smell of hydraulic oil.

（5）Tactile diagnose : To take advantage of sensitive finger touching, and 

check whether the shaking and shock occurs and whether the oil temperature 

is in a normal range.