液压是指升降机在升降过程中的动力来源及传动方式，液压传动固然离不开最重要的部位—液压油缸。
Hydraulic lifts the lifting process refers to the power source and transmission mode, the hydraulic drive of course inseparable from the most important part - the hydraulic cylinder.
液压系统是液压升降机中的重要部分，液压油缸是液压系统中的执行机构；一般由缸体，缸杆及密封件组成，缸体内部由活塞分成两个部分，分别通一个油孔。由于液体的压缩比很小，所以当其中一个油孔进油时，活塞将被推动使另一个油孔出油，活塞带动活塞杆做伸出运动，反之亦然。
Hydraulic systems are an important part of the hydraulic lifts, hydraulic cylinder is a hydraulic system actuators; generally by the cylinder, the cylinder rod and seals composed by the piston inside the cylinder is divided into two parts, namely through a hole. The compression ratio of the liquid is small, so that when one of the oil feed hole, so that the piston will be pushed further out of the oil hole, the piston drive rod extending do sports, or vice versa.
Hydraulic lift hydraulic cylinders used, its components usually has five parts: a piston and piston rod, cylinder and cylinder head, cushioning devices, seals, exhaust. Works with conventional hydraulic cylinders are similar, take a manual jack, the jack in fact, is the most simple cylinder.
液压油缸是液压升降机最重要的组成部分，但是液压油缸在整个设备的保养维护中并不是非常重要，因为液压油缸其结构和材质决定了，它的高承载，简单结构，不易损坏。
Hydraulic cylinder is a hydraulic lift most important part, but the hydraulic cylinders in the maintenance of the entire device is not very important, because the hydraulic cylinder determines its structure and material, its high load-bearing structure is simple, easy to damage.