When the hydraulic system pressure or no pressure, can be diagnosed according to the following method.

A look at the hydraulic pump can output hydraulic oil. If no hydraulic oil output, it may be wrong: steering pump; parts wear or damage; suction tube resistance is too large(oil filter plugging, oil viscosity is too large) or leakage. If this is a new pump, may be the pump body casting defects (such as sand hole), the oil suction chamber and the pressure chamber, lost oil pressure; the input power of the pump or pump shaft is broken, so that the output pressure oil pump is not up to the job stress or lose no oil.If the hydraulic pump oil output, you should check the oil return pipe, which is acomponent of the oil spill. Such as overflow into the oil spill, may be the valve set pressure adjustment due to low. At this time, can tighten the relief valve pressure regulating spring, if no pressure changes, may be the cone valve relief valve main valve or pilot portion of the dirt or due to corrosion and stuck in the open position; or because of spring broken and useless; or because of damping holes are blocked by dirt, so that the output of the oil pump directly the relief valve to tank, resulting ininsufficient pressure or without pressure. Rule is, open the overflow valve and cleaning; check or replace the spring, resumed its work performance.

Two see overflow valve is working properly. If it is not normal, it may be a valve pressure oil in the dirt or other reasons is the card, in the oil return position, thepressure oil circuit is communicated with the overflow loop. May also be pipe joint isloose, or in a certain pressure, the oil in the serious leakage, sealing or hydraulic cylinder, hydraulic motor parts damaged, resulting in serious leakage. Elimination method is concerned, open the valve for cleaning, size and check the sealing device.If the seal is damaged, should be replaced.

Three see of the hydraulic pump output flow. If the flow with the pressure increasesand decreases, and the pressure is not up to the specified value, is due to the hydraulic pump wear gap increased by. Method: the volumetric efficiency of hydraulic pump can be measured to determine whether or not the pump can continue to use,the worn parts, repair or replacement shall be carried out.

Four see the entire hydraulic system can establish normal pressure. Some of the pipeline or hydraulic cylinder (hydraulic motor) without pressure, may also be due topipe, throttle valve, reversing valve and other components is blocked. To bepiecewise check pressure and no oil through, find out the reasons, be excluded.