What are the common gantry crane hydraulic system failure (two)

What are the common   overhead gantry crane  hydraulic system failure (two)

Followed by the action too slow. Actuator hydraulic system mainly refers to the hydraulic motor and the hydraulic cylinder. If the actuator action is too slow, ① hydraulic motor or hydraulic cylinder own fault, such as severe internal leakage or leakage which can result in slow movements and actions weakness. ② Because the hydraulic motor or hydraulic cylinder flow decreases due, which in turn points two reasons, first, the hydraulic pump to pump flow decreases, such as severe internal leakage, can significantly reduce the pump flow rate, the variable pump , the pump flow and the impact of regulation by itself, sometimes due to improper adjustment flow rate decreases; Second, the control valves and piping failures, such as the valve opening degree of catching the decrease, resulting in lower flow rate, if the Hydraulic oil and other foreign matter mixed into the yarn, the pipeline flow is reduced also cause blockage. A  KH700-2 crawler crane manufacturers combined pump overhaul by a professional, found all movements are slow, and the speed is still less than the pre-overhaul of 1/3. This can basically rule out oil or actuator causes are blocked unless all oil or hydraulic motor fails, it is almost impossible. Only the root causes of failure in the hydraulic pump, the pump flow is reduced. After the pump, it was discovered that the ends of the pump flow control valve to adjust properly due to re-adjust after correction flow restoration, all the action is also restored to the original design speed.

    A KH180-3 crawler   bridge gantry crane  lewing brake solenoid valve due to poor work to understand medical repair. In the valve body to be demolished, since the valve body is symmetrical oil passage, the spool structure is essentially the same longitudinal direction, I think that the valve body in the longitudinal direction can be interchanged. Therefore, during operation, is not necessary to mark its direction. But after re-assembly, machine work slow (less than the original speed of 1/2 of the maintenance work carried out only cleaned the solenoid valve, the problem probably lies in the disintegration over the solenoid valve, but the solenoid valve in the work no other anomalies. finally decided to re-disintegration of the solenoid valve After careful measurements on the spool, the spool ends glossy found some deficiencies in length with 1mil differences, which previously suspected The valve installed backwards, then has changed the direction of the spool reassembled everything back to normal after installation.