对于混凝土搅拌车来说，液压系统是非常重要的，装料，卸料，搅拌罐的转动等都离不开液压系统，很多混凝土搅拌车都会遇到液压系统的压力不足，这到底是为什么呢？

For the concrete mixer, the hydraulic system is very important, loading, unloading, mixing tank rotation are inseparable from the hydraulic system, many concrete mixers will encounter insufficient pressure of the hydraulic system, which in the end is why?

混凝土搅拌车液压系统压力不足，一般有4个方面的原因：

There are four reasons for the insufficient pressure of hydraulic system of concrete mixer

1. 液压泵能不能输出液压油，如果没有液压油输出，就可能是泵的转向不对，零件磨损严重或损坏：吸油管阻力过大（滤油器阻塞，油液粘度过大等）或漏气。如果是新的液压泵，可能是泵体有铸造缺陷，比如砂眼、缩孔等，使吸油腔和压油腔相通，失去压油能力，输入功率不足，使泵的输油压力达不到要求，泵轴扭断，而输不出油。若液压油泵有油输出，则应检查各回油管，观察哪个部件漏油。假如溢流阀回油管漏油，可能是调定压力低。此时，拧紧溢流阀调压弹簧，若压力没有变化，则可能是溢流阀主阀芯或先导部分的锥阀因脏污或锈蚀而卡死在开口位置；或因弹簧折断失去作用；或因阻尼孔被脏物堵塞，泵输出的油液立即经溢流阀流向回油箱。排除方法：拆开溢流阀，加以清洗，检查或更换弹簧，恢复其工作性能。

1. Whether the hydraulic pump can output hydraulic oil, if there is no hydraulic oil output, it may be that the steering of the pump is not right, the parts are seriously worn or damaged: the resistance of the oil suction pipe is too large (the oil filter is blocked, the oil viscosity is too high, etc.) or the air leaks. If it is a new hydraulic pump, it may be that the pump body has casting defects, such as sand holes, shrinkage holes, etc., which make the oil suction chamber and the oil pressure chamber connected, lose the oil pressure capacity, and the input power is insufficient, so that the oil delivery pressure of the pump can not meet the requirements, and the pump shaft is twisted and can not output oil. If there is oil output from the hydraulic oil pump, check each oil return pipe to see which part is leaking. If the return pipe of the relief valve leaks oil, the setting pressure may be low. At this time, tighten the pressure regulating spring of the relief valve. If the pressure does not change, the main valve core of the relief valve or the cone valve of the pilot part may be stuck in the open position due to dirt or corrosion; or the spring may be broken and lose its function; or the damping hole may be blocked by dirt, and the oil output from the pump will immediately flow to the oil tank through the relief valve. Troubleshooting: disassemble the relief valve, clean it, check or replace the spring, and restore its working performance.

2. 混凝土搅拌车，溢流阀工作是否正常，如果不正常，则可能是压力油路中的某个阀有污物或其他原因卡住，处于回油位置，致使压力油路与溢流阀回路短路，也可能是管接头松脱，或处于压力油路中的某些阀泄漏严重，或液压缸、液压马达的密封件损坏，严重泄漏。排出办法：拆开有关阀门进行清洗，检查密封间隙的大小或各种密封装置，如果密封装置损坏应更换。

two Whether the overflow valve of concrete mixer works normally, if not, it may be that a valve in the pressure oil circuit is stuck by dirt or other reasons and is in the oil return position, resulting in a short circuit between the pressure oil circuit and the overflow valve circuit, or it may be that the pipe joint is loose, or some valves in the pressure oil circuit leak seriously, or the seals of the hydraulic cylinder and hydraulic motor are damaged, resulting in serious leakage . Discharge method: disassemble the relevant valve for cleaning, check the size of the sealing gap or various sealing devices, and replace the sealing device if it is damaged.

3. 若液压泵输出流量随压力升高而显著减小，且压力达不到规定值，则是由于液压泵磨损后间隙加大所致，排除方法：测定液压泵的容积效率，即可确定该泵是否能继续使用，对磨损严重的零件，应加以修配或者更换。

3. If the output flow of the hydraulic pump decreases significantly with the increase of the pressure, and the pressure does not reach the specified value, it is due to the increase of the clearance after the wear of the hydraulic pump. The elimination method: by measuring the volumetric efficiency of the hydraulic pump, it can be determined whether the pump can continue to be used, and the parts with serious wear should be repaired or replaced.

4. 如果整个混凝土搅拌车液压系统能建立正常压力，而某些管路或液压缸，液压马达中无压力，则可能是由于管路、小孔或节流阀、换向阀等部位堵塞，这时应逐一检查压力和有无油液通过，找出原因再加以排除。

4. If the hydraulic system of the whole concrete mixer can establish normal pressure, and there is no pressure in some pipelines or hydraulic cylinders, the pipeline, small hole or throttle valve, directional valve and other parts may be blocked. At this time, check the pressure one by one and find out the cause before removing.