The bucket rod telescopic cylinder slow and weak

　　当长臂挖掘机在作业过程中出现斗杆缸伸缩缓慢无力时，我们应当做如下检查。

　　When the long arm of the excavator during the operation of the bucket rod cylinder expansion appears slow and weak, we should check the following.

　　1.查看其密封件是否失效。先松开低压腔的油管，放掉腔内液压油，然后启动发动机给高压腔内注入压力油，未见液压油从低压腔的油管中流出，表明斗杆缸活塞密封件密封良好。若密封件失效则会造成低压腔与高压腔的液压油因内泄而互窜。

　　1. see the seal failure. Loosen the tubing pressure chamber, put the oil inside, and then start the engine oil injection pressure to the high pressure chamber, no hydraulic oil flowing from the low-pressure chamber tubing in that bucket rod cylinder piston seal good. If the hydraulic oil seal failure will result in the low pressure chamber and the high-pressure chamber due to internal leakage and channeling.

　　2.查看吸油阀是否正常。吸油阀是1个双向保护阀，安装在液压缸和液压马达等执行元件上，当液压缸或马达的某一腔产生瞬间高压时，高压腔的高压油就会打开吸油阀中的溢流阀进行溢流，同时负压腔吸油阀的单向阀打开，从油箱吸油来补充负压，起到保护油路作用。

　　2. see the safety of suction valve is normal. Safety is a two-way suction valve 1 protection valve installed in the hydraulic cylinder and a hydraulic motor actuator, when the hydraulic cylinder or motor of a cavity to produce instantaneous high voltage, high pressure oil will overflow the high pressure chamber safety relief valve suction valve in the open at the same time, the negative pressure cavity suction one-way valve oil safety valve open to supplement, negative pressure suction from the tank, play a protective role of oil.

　　由于斗杆缸工作回路上装有2个吸油阀，若其中某个吸油阀的单向阀失效变成双向直通，或者在溢流阀溢流压力很低时，都会造成该侧油腔的油压不能建立，压力油直接通过单向阀或溢流阀泄入油箱，使斗杆缸动作缓慢无力甚不能工作。若吸油阀存在此故障则操作手柄处于中立位置停机后，斗杆缸会自动缓慢回落;反之若无此现象则可排除吸油阀故障。

　　The 2 safety suction valve equipped with bucket rod cylinder loop, if the one-way valve a safety valve oil failure into a two-way through, or in the overflow of the overflow valve pressure is very low, will cause the oil chamber of the hydraulic side can not be established, the pressure oil directly through the one-way valve or overflow relief valve into the tank the bucket rod cylinder, slow weak or unable to work. If the suction valve exists for the fault of operating lever is in neutral position after the shutdown, the bucket rod cylinder will automatically slow down; if no such phenomenon can eliminate safety suction valve fault.

　　3.检查PPC阀和主控制阀。PPC阀又称先导操纵阀，是一种比例压力控制阀，可依据操作手柄行程的大小输出相应的控制压力及流量，使主控制阀芯存在相应的移动量，从而起到控制执行元件速度的作用。主控制阀中每一根阀芯控制一支油路的通断，若其中某一阀芯磨损、卡滞甚堵塞，就会降低相应执行元件的油压和流量，造成执行元件动作迟缓甚无动作。

　　3. PPC check valve and main control valve. PPC valve as the pilot control valve, a proportional pressure control valve, according to the size of the operating handle stroke output pressure and flow control accordingly, the main control valve has corresponding amount of movement, so as to control the speed of the actuator. The main control valve in each valve to control a circuit switching, if one valve wear, stagnation or even blocked, it will reduce the corresponding actuator pressure and the flow, causing the actuator action slow or even no action.

　　将斗杆缸回路的控制油管调换到工作正常的PPC阀上试机，则该故障消失。

　　The control circuit of the bucket rod cylinder tubing replacement to PPC valve working on the test machine, the fault disappears.