Hydraulic cylinder

A hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment (engineering vehicles), manufacturing machinery, and civil engineering.

Hydraulic cylinders get their power from pressurized hydraulic fluid, which is typically oil. The hydraulic cylinder consists of a cylinder barrel, in which a piston connected to a piston rod moves back and forth. The barrel is closed on one end by the cylinder bottom and the other end by the cylinder head where the piston rod comes out of the cylinder. The piston has sliding rings and seals. The piston divides the inside of the cylinder into two chambers, the bottom chamber and the piston rod side chamber.

Flanges, trunnions, clevises, and lugs are common cylinder mounting options. The piston rod also has mounting attachments to connect the cylinder to the object or machine component that it is pushing or pulling.

Hydraulic Cylinder Repairs

Hydraulic cylinders form the heart of many hydraulic systems. It is a common practice to dissemble and rebuild an entire device in the case of hydraulic cylinder repair. Inspection of the leakage issue and scrutinizing cylinder parts (especially the seals) is helpful in recognizing the exact problem and choosing the repair options accordingly.

Steps involved in the repair of hydraulic cylinders.


First of all, you should place the cylinder in a suitable location, which has sufficient space to work. If you are working in a cluttered space, it will be difficult for you to keep track of opened up parts. After bringing the cylinder to an appropriate spot, open the cylinder ports and drain out all the hydraulic fluid. The cover of cylinder can be removed by unscrewing the bolts. Once you take off the cover, remove the piston by loosening the input valves.


Once the piston is completely removed, you will be able to see multiple seals on different parts that are connected to the piston rod. First of all, you need to examine the piston rod to see if there is any damage. If the shaft of the rod is bent or if the cylinder bore has scratches, then get them repaired at a professional repair shop. If the damage is permanent, then you can order or manufacture a new piston rod for your hydraulic cylinder. Piston seals can get damaged, be distorted, or worn. Such damaged seals can cause leakage of hydraulic fluid from the cylinder leading to lower overall pressure or inability to hold pressure. When such events occur, you know that these seals need to be replaced.

Repairing or replacing damaged parts

The parts of the hydraulic cylinder that are distorted (piston rod, rod seal, piston seal and/ or head of rod), need to be either repaired or completely replaced with new parts.

The seals can be repacked with the help of a hydraulic cylinder seal kit. These kits will have seals and suitable O-rings. Remember the size and type of old seal while removing them and fix the new ones accordingly. Make sure that you handle the new seals with utmost care so that they do not get damaged in any way.


Before reassembling all the parts of your cylinder, you should clean and dry the cylinder barrel completely. Also clean the piston rod, shaft, and other parts of the cylinder. Get the broken and damaged seals repacked. Then assemble the parts back on the piston rod. The assembly needs to be done in a reverse order. Once you have assembled all the parts back, put the rod into the soft-jaw vise and screw back the bolts onto the piston rod.

Important tip

If the parts of the hydraulic cylinder are severely damaged, then it is advisable to replace them with new parts with the help of a professional repair expert. Trying to replace/ repair too many parts on your own can lead to faulty reassembly. By following the above steps, you can accomplish the task of hydraulic cylinder repair. Make sure that you prevent ingress of moisture or dirt after assembly of the parts is done

View the various Hydraulic Cylinders we manufacture and repair below.