The multi-stage hydraulic cylinder has many characteristics, such as its compact structure, and can achieve a longer stroke than the single stage hydraulic cylinder in a given installation space, because of such characteristics, multi-stage hydraulic cylinder has been widely used in the case of tight installation space. For example, tipping bucket hydraulic cylinder of dump truck, push shovel hydraulic cylinder of garbage station, lifting hydraulic cylinder of equipment handling bridge frame and other places have been applied to multi-stage hydraulic cylinder. The current domestic design or by a lot of insufficient, rarely in the domestic hydraulic cylinder design to its structure classification, stress calculation, selection of materials and processing technology, seal for a more detailed introduction, in the long run, this situation will cause the designers now have no way to study of the existing design experience.

At present, there are many common multi-stage hydraulic cylinder structures in the market. Three cylinder is the typical use of multi-stage hydraulic cylinder, more serious is the other a variety of multi-stage cylinder structure and working principle are basically based on the three stage hydraulic cylinder structure and working principle to expand and build, garbage station push shovel hydraulic cylinder typical multi-stage hydraulic cylinder. It works like this. Normally, the pressure oil flows in and out of the rod head and eventually ACTS on the left and right sides of the piston to extend and retract, so it is called the piston type multi-stage hydraulic cylinder. When the multi-stage hydraulic cylinder is working, the high pressure oil will enter from the inlet and flow through the tubing, and then it will reach the right side of each piston of each level. Due to the difference of acting area, the piston rod of the first level hydraulic cylinder can be pushed from large to small in order to make it extend to the left. In this case, the low pressure oil will flow from the first stage hydraulic cylinder has a bar cavity through the small orifice and then flow to the second stage hydraulic cylinder has a bar cavity through the small orifice and then flow to the third stage hydraulic cylinder has a bar cavity through the small orifice, and finally flow through the small orifice to the bar head, and finally flow out of the outlet.

Multistage hydraulic cylinder generally has single and double action, and its expansion level can vary from two to five levels. At present, the multi-stage hydraulic cylinder in the market has the characteristics of compact layout, reasonable structure, reliable work, convenient installation and disassembly, easy maintenance and so on. So multi-stage hydraulic cylinder is widely used in all kinds of construction machinery, mining machinery, lifting transport machinery, environmental protection machinery, traffic machinery (cleaning vehicles) and so on.