Hydraulic cylinders come in various structural forms and can be classified in multiple ways: by motion (linear reciprocating and rotary swing); by hydraulic pressure (single-acting and double-acting); by structure (piston, plunger, multi-stage telescopic sleeve, rack and pinion, etc.); by mounting method (connector rod, clevis, foot, hinge pin, etc.); and by pressure rating (16 MPa, 25 MPa, 31.5 MPa, etc.).
Piston-type hydraulic cylinders can be further divided into single-rod and double-rod structures, fixed by either the cylinder body or the piston rod. They are also classified as single-acting or double-acting based on the hydraulic pressure applied. In a single-acting hydraulic cylinder, hydraulic oil supplies only one chamber, enabling unidirectional movement. Reverse movement is achieved by external forces (such as spring force, weight, or external load). In a double-acting hydraulic cylinder, the piston's movement in both directions is accomplished by alternating oil supply to both chambers, relying on hydraulic pressure.
