装载机在动臂操作手柄扳到动臂下降位置时，动臂不是平稳下降，而是间歇下降，造成整机前后摇晃，动臂起升过慢，出现这种现象是怎么回事呢？

引起这种现象的原因可能是装载机起升滑阀卡滞，在动臂下降过程中，阀芯滑动不畅，油口不能完全打开，使动臂缸有杆腔进油不足，而当翻斗加载时，动臂在自重的作用下，有杆腔的容积增大速度大于进油速度，出现负压。这时在无杆腔产生一个反作用力，阻止液压缸活塞向无杆腔滑动，当作用力与反作用力达到平衡时，就会造成动臂停止下降。而这时有杆腔仍然在进油，负压逐渐减小，液压缸两腔又需要达成新的平衡，这样就造成了动臂断续下降，并引起整机的剧烈摇晃。当山东装载机空载时，由于自重减小，下降速度减慢，故障现象不明显。当动臂起升时，因为需要油压将动臂顶起，不会产生负压，但因阀芯打开不完全而造成动作缓慢。
The reason for this phenomenon is probably caused by Shandong loader lifting spool valve sticking, in the boom-down process, the valve slide poor port can not be completely open, so that the boom cylinder rod chamber into the lack of

oil, and when when the dump load, boom under the action of gravity, there is an increase in the volume of the rod chamber faster than the inlet velocity, appear negative. Then in the rod chamber to generate a reaction force to prevent hydraulic cylinder piston rod chamber slide, when the action and reaction equilibrium, it will cause a boom stopped falling. And then there is still the rod into the oil chamber, the negative pressure decreases, the hydraulic cylinder two chambers and the need to reach a new equilibrium, thus causing intermittent boom down and cause violent shaking machine. When Shandong loaders load, due to the weight decreases, the rate of decline slowed, the fault is not obvious.When lifting the boom when the boom because of the need hydraulic jacking, will not produce negative pressure, but not completely open the valve and cause slow.

这时应该拆检装载机主控阀，阀芯有些卡滞，清洗后试验，仍有卡滞，再用卡尺测量，发现阀芯失圆，更换新阀后，故障解除。
At this point it should be overhauled Shandong loader master valve spool some catching, after cleaning the test, there are still catching, then caliper, found the spool out of round, after valve replacement, the fault is removed.