Hydraulic system is based on hydraulic oil as the working medium, through the pump, cylinder oil motor output energy. These two parts in the fault detection is neither as intuitive as the mechanical structure, nor as easy as the electrical structure measurement, so in the fault detection to master the theory of hydraulic technology, hydraulic components and system on the basis of the structural principle, to judge and reason, now according to the fault phenomenon to infer the cause of some experience:
1. Pump
(1) Inspection of internal leakage.
First close the relief valve, if the system pressure rise is not high, the oil tank return port and rarely return oil, you can be sure of hydraulic pump friction loss; If under normal pressure, the relief valve does not open, and the speed of the working parts is insufficient, it can also be determined that the pump has an internal leak.
(2) If the pump does not produce oil, the suction pipe is bubbling instead, then the motor may be installed in reverse, change the motor steering, this failure occurs after the maintenance of the motor or electrical line.
(3) When the pump starts to work, the noise is normal, but after running for a period of time, there is a larger noise, producing a relatively low call, which is the noise generated by cavitation, and the mechanical noise is sharper and easy to distinguish. At this time, the oil in the tank turns yellow and white because of small bubbles, which proves that the system is mixed with air and should be checked to prevent air from entering the system.
2, hydraulic cylinder
(1) Detect whether the cylinder has internal leakage, adjust the pressure of the relief valve to the limit pressure of the system, observe the situation of the hydraulic cylinder in the extended position to determine whether there is internal leakage, at this time if there is only a small leak, indicating that the cylinder performance is good, if the leak is large, it indicates that the sealing ring on the piston has been damaged and failed. If the piston seal is good, the leakage of the piston in the two limit positions should be basically equal, otherwise it means that the cylinder end cap seal problem should be repaired in time.
(2) When the cylinder is moving, there is the friction sound of the sliding metal, which is caused by the oil film of the sliding surface being destroyed or the pressure is too high, and it must be stopped immediately for inspection, otherwise it will lead to the sintering of the sliding surface.
(3) The cylinder is always crawling in a certain part of the operation process, then you can first unload, reciprocating empty line, if the piston in the same part of the resistance becomes large, it may be due to scars or sintering.
