Hydraulic system pressure is not normal mainly because the work pressure can not build up, rise less than the set value or rise down after the down, the reason often with the engine, pumps and valves and many other parts.
In the overhaul, according to the engine, pump and valve and other parts of the function, in order to isolate a loop or a component were diagnosed, respectively, and finally found out the real cause of the malfunction and excluded.
Hydraulic pump failure and troubleshooting
1, pump parts with the gap beyond the required requirements, causing pressure pulsation or pressure rise is not high. Such as gear pump radial clearance should be controlled between 0.13-0.16mm, the axial clearance should be controlled between 0.03-0.04mm, beyond which the parts should be repaired, adjusted or replaced.
2, hydraulic pump inlet and outlet should not leak or enter the air. In determining whether there is air entering, the seal can be coated with butter to see whether the pump noise is significantly reduced. If it is confirmed that air enters, exhaust measures should be taken.
3, pump parts processing quality and assembly quality is poor, such as gear pump gear meshing surface poor contact. Should be strictly processing, assembly quality management.
4, the pump inlet and outlet tubing reversed. Should be replaced by reconnection, before starting pump filled with hydraulic oil.
5, the leaves of the vane pump stuck, equipped with anti, the vane and the pump body surface in poor contact with the curve; plunger pump plunger stuck. If the blade or bearing damage, piston spring deformation failure, should be replaced;
Trouble and Solution of Hydraulic Pump Drive Motor
1, the motor is not turning. Should be transferred line commutation;
2, motor power shortage or speed does not meet the requirements. Should check the voltage, check the motor performance.
Pressure relief valve malfunction failure and troubleshooting
1, the main spool of the clogging of the damping orifice, the hydraulic pressure less than the main valve cavity and the pre-valve cavity, the pilot valve thus losing the main valve pressure regulation, the system pressure can not build up. Should be cleaned overflow valve, dredge orifice.
2, the pressure regulator spring deformation, valve leakage is too large or excessive pilot valve cone valve, so that the pressure can not be set value. Replace springs, cone valves and seals.
3, the pilot valve cone valve seat blocking the small holes, the hydraulic pressure less than the cone valve on the pilot valve to lose the role of regulation of the main valve in any pressure can not drain the pressure rising. Pilot valve should be cleaned to unblock the orifice.
4, relief valve seal damage, the main spool and cone valve wear is too large, resulting in serious internal and external leaks, the pressure is not stable, fluctuated. Should replace the damaged seals, spool.
5, the main spool radially chucking, can not achieve regulatory function, resulting in pressure on or not coming down. Should be demolished, cleaning the body, troubleshooting.
6, relief valve main spool damping orifice blockage, so that the main spool in a very low pressure to open. Should be cleaned overflow valve, dredge damping holes, so that the relief valve to normal pressure regulation function.
7, due to pollution, burrs and other reasons, make the relief valve core stuck in the open or closed position, the former system pressure can not be increased, which makes the pressure suddenly increased and down not down. Check the relief valve should be dismantled, find the cause of stuck, after the thorough removal of cleaning, assembly. Test conditions should be allowed when the test bench to confirm no problem before loading the system.
Regulating valve failure failure and troubleshooting
1, due to the following reasons, adjust the pressure regulating hand wheel, the relief valve outlet pressure can not rise. ① The main spool orifice clogging. Should be cleaned to clear. ② main valve relief valve port closed, the main spool stuck outside the control port is not blocked. Valve plugging failure should be ruled out, cleaning the body, plug the external control port.
2, pressure relief valve outlet pressure due to the following reasons can not rise to the rated pressure value. ① pressure regulating spring permanent deformation, compression stroke is not enough. Should be adjusted in the spring base gasket, if there is no improvement to be replaced. ② cone valve wear is too large. Cone valve should be cleaned, replace damaged parts.
3, because of the following reasons to adjust the pressure regulating handwheel can not change the pressure after the valve, and the oil outlet pressure with the oil inlet pressure rise or fall at the same time. ① cone valve seat damping orifice plugged. Should clean the cone valve, unblocking orifice; ② one-way valve one-way valve serious leak. The O-ring should be replaced. ③ The main spool stuck in the fully open position. Should be cleaned and removed.
4, Bian spool stuck, resulting in regulation pressure regulating hand wheel failure. The outlet pressure can not be reduced. Should be cleaned and excluded; if the valve core deformation should be replaced.
5, the main spool with loose or worn too large, so that the pressure relief valve in the work after setting the pressure of the oil outlet. Raise yourself. Main spool should be replaced.
Pressure is not normal other reasons and eliminate
1, the filter plug, the flow channel is too small and the viscosity of the oil is too high, so that the oil is not drawn. Should clean or replace the oil filter, replace the hydraulic oil.
2, the oil into excess air. Should exhaust.
3, the wrong pipe line. Should check and reconnect.
4, motor power shortage, speed is too low. Should check the motor fault and be excluded, if necessary, re-check the motor specifications and performance.
5, oil viscosity is too low, serious leakage. Should replace the hydraulic oil and seals.
6, pressure gauge damage. Should be replaced.
Excavator running deviation2017-04-14