對于混凝土攪拌車來說，液壓系統是非常重要的，裝料，卸料，攪拌罐的轉動等都離不開液壓系統，很多混凝土攪拌車都會遇到液壓系統的壓力不足，這到底是為什么呢？

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?

混凝土攪拌車液壓系統壓力不足，一般有4個方面的原因：

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

1. 液壓泵能不能輸出液壓油，如果沒有液壓油輸出，就可能是泵的轉向不對，零件磨損嚴重或損壞：吸油管阻力過大（濾油器阻塞，油液粘度過大等）或漏氣。如果是新的液壓泵，可能是泵體有鑄造缺陷，比如砂眼、縮孔等，使吸油腔和壓油腔相通，失去壓油能力，輸入功率不足，使泵的輸油壓力達不到要求，泵軸扭斷，而輸不出油。若液壓油泵有油輸出，則應檢查各回油管，觀察哪個部件漏油。假如溢流閥回油管漏油，可能是調定壓力低。此時，擰緊溢流閥調壓彈簧，若壓力沒有變化，則可能是溢流閥主閥芯或先導部分的錐閥因臟污或銹蝕而卡死在開口位置；或因彈簧折斷失去作用；或因阻尼孔被臟物堵塞，泵輸出的油液立即經溢流閥流向回油箱。排除方法：拆開溢流閥，加以清洗，檢查或更換彈簧，恢復其工作性能。

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. 混凝土攪拌車，溢流閥工作是否正常，如果不正常，則可能是壓力油路中的某個閥有污物或其他原因卡住，處于回油位置，致使壓力油路與溢流閥回路短路，也可能是管接頭松脫，或處于壓力油路中的某些閥泄漏嚴重，或液壓缸、液壓馬達的密封件損壞，嚴重泄漏。排出辦法：拆開有關閥門進行清洗，檢查密封間隙的大小或各種密封裝置，如果密封裝置損壞應更換。

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. 若液壓泵輸出流量隨壓力升高而顯著減小，且壓力達不到規定值，則是由于液壓泵磨損后間隙加大所致，排除方法：測定液壓泵的容積效率，即可確定該泵是否能繼續使用，對磨損嚴重的零件，應加以修配或者更換。

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. 如果整個混凝土攪拌車液壓系統能建立正常壓力，而某些管路或液壓缸，液壓馬達中無壓力，則可能是由于管路、小孔或節流閥、換向閥等部位堵塞，這時應逐一檢查壓力和有無油液通過，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.