The Function of Seals In a Hydraulic Cylinder

Hydraulic Cylinder repair is a straight forward task if you have an understanding of how hydraulic cylinders work, or at least what O-rings, and rubber seals allow for the cylinder to work. This blog is aimed at the later, in this blog we will be discussing typical sealing components that allow a hydraulic cylinder to operate. Something to remember when repairing hydraulic cylinders is that you must have a way to take the rod and glands out of the casing, you cannot repair a hydraulic cylinder without disassembling the cylinder components.

Rod wipers: Rod Wiper seals are one of the first sealing components that you will find when repairing hydraulic cylinder seals. The wiper seals serves the function of cleaning the hydraulic cylinder rod before it re-enters the casing. This allows for the prevention of dirt, and other hard contaminants from entering the hydraulic fluid and damaging the rod itself and buffer seals.

Rod seals: Rod seals assist in preventing hydraulic fluid from leaking from the rod of a hydraulic cylinder, similar to the rod wiper seal, it also contributes to the wiper in the prevention of contaminating the hydraulic fluid.

Rod wear rings: Also known as Wear bands, these components do not serve the function of sealing, but instead the function is to guide both the piston and the rod within the casing. These bands prevent any structural damages to the cylinders gland inside the casing. If there are contaminants that enter the cylinder the containment's will degrade the wear rings before the gland components is damaged.

Buffer rings: The main function of the buffer ring in the hydraulic cylinder is to protect the rod from the effects of pressure, and shock loading. Without this seal, the lifespan of the cylinder is greatly reduced.


Piston seals: Piston seals have the same function as the rod seal, the difference however is that, the piston seal ensures that pressurized fluid cannot move past the piston as it moves within the cylinder casing. Unlike the rod seal that is found in the gland closest to the rod tip the piston seal is not meant to be exposed to contaminants. Therefore if the cylinder has a faulty or weak rod seal, there will eventually be a degradation to the function of the piston seal, thus creating serious problems for the hydraulic cylinder.

 Piston wear rings: The piston wear ring serves the same function as the rod wear rings in the cylinder. To protect the piston gland from being damaged by moving within the casing.

Though Custom Hydraulics & Design does not directly offer hydraulic cylinder repair services, we are fully capable of assisting you in the replacement of the glands sealing components. For this service we ask that the hydraulic cylinder is disassembled and only the glands are brought into the Charlotte and Mooresville locations. For complete hydraulic cylinder rebuilds, rod repairs, alterations, and casing corrections we have teamed up with a local fabrication service to assist you.