There are primarily two styles of hydraulic cylinder construction used in industry: tie rod and welded body cylinders. Beyond this, other broad types of cylinder design include telescopic, plunger, differential, re-phasing and single and double-acting hydraulic cylinders.
Hydraulic cylinders are usually double-acting: oil under pressure can be applied to either side of the piston to provide movement in either direction. Single-acting cylinders are sometimes used where the weight of the load is used to return the cylinder to the closed position.
Hydraulic cylinders enable more flexibility in design and structure when transferring force between two different points. Different sized cylinders make it possible to create a system that can pull, push and lift weights; bends and corners can be incorporated into the system design – useful if there are real space constraints.
However, a hydraulic cylinder should only be used for linear pushing and pulling. No bending moments or side loads should be transmitted to the piston rod or the cylinder. For this reason, a cylinder should ideally be connected by using a single clevis with a spherical ball bearing. This allows the cylinder to move and allows for any misalignment between it and the load it is pushing.