裝載機動臂間歇下降是怎么回事？

裝載機在動臂操作手柄扳到動臂下降位置時，動臂不是平穩下降，而是間歇下降，造成整機前后搖晃，動臂起升過慢，出現這種現象是怎么回事呢？

引起這種現象的原因可能是裝載機起升滑閥卡滯，在動臂下降過程中，閥芯滑動不暢，油口不能完全打開，使動臂缸有桿腔進油不足，而當翻斗加載時，動臂在自重的作用下，有桿腔的容積增大速度大于進油速度，出現負壓。這時在無桿腔產生一個反作用力，阻止液壓缸活塞向無桿腔滑動，當作用力與反作用力達到平衡時，就會造成動臂停止下降。而這時有桿腔仍然在進油，負壓逐漸減小，液壓缸兩腔又需要達成新的平衡，這樣就造成了動臂斷續下降，并引起整機的劇烈搖晃。當山東裝載機空載時，由于自重減小，下降速度減慢，故障現象不明顯。當動臂起升時，因為需要油壓將動臂頂起，不會產生負壓，但因閥芯打開不完全而造成動作緩慢。
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.

這時應該拆檢裝載機主控閥，閥芯有些卡滯，清洗后試驗，仍有卡滯，再用卡尺測量，發現閥芯失圓，更換新閥后，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.