Yipeng Hydraulic jacks used on engine hoists come in various different lifting capacities and sizes and usually depends on the maximum lifting capacity of the hoist. For example, an engine lifter with a maximum lifting capacity of 2 tons (4000 lb) will likely be equipped with a hydraulic ram that has a maximum capacity of 8 tons (16000 lb). We can see this practice on many lifting units, the lifting capacity of the ram is 4 times larger than the total lifting capacity of the whole engine lifter.

Hydraulic jack used on an engine hoist has similar parts to other hydraulic jacks, the main difference is that these jacks are taller in height, so that the ram can lift the boom of a hoist in a greater height. The jack consists of a cylinder, where the hydraulic fluid is held, around the cylinder is an oil chamber. Oil is used as a hydraulic fluid, because it also lubricates other parts of the jack. Inside the cylinder is a ram which is moved up or down by increasing or decreasing the oil pressure inside the cylinder. On the bottom of the ram inside the cylinder is a piston, which is properly sealed, to not let the pressure to bypass on the other side. On top of the ram a boom of the hoist is attached, so pumping the jack will raise the boom. There are multiple smaller copper washers, o-rings and sealing gaskets inside the jack to properly seal the oil, so the jack does not start to leak oil while lifting heavy loads.

On the side of the jack is a pumping system that moves oil from one cylinder to other. The pumping system consists of a pump cylinder, a handle socket, a handle, which is inserted into the handle socket and hand powered to apply pressure inside the cylinder, and other small rings, pins, links and steel balls to cover the pump cylinder and washers.

All in all, hydraulic jacks are pretty simple devices when looking at their construction, but they are capable to lifting very large amounts of weight, applying relatively small amount of force to them. http://www.yipengjack.com/