Guide to Understanding Hydraulic Cylinder Parts: Names & Diagram

A hydraulic cylinder is a mechanical actuator that gives a unidirectional motion through the force of the hydraulic liquid. It is also referred to as a linear hydraulic motor. It has a wide area of applications, ranging from the construction industry to mechanical machines. Without this, we can not see the enormous development of the nations. Different hydraulic cylinder parts make the massive machine very efficient to work in any environment. Its design is simple, and it is the same from an early age. Let’s see all the parts of the hydraulic cylinder with their names and diagrams.

Hydraulic Cylinder Parts Diagram

Hydraulic Cylinder Parts, Names, and Diagram

Hydraulic Cylinder Parts Name

  • Cylinder Barrel
  • Base
  • Cylinder Head/End Cap
  • Piston
  • Piston Rod
  • Seal Gland
  • Seals

Parts of a Hydraulic Cylinder

Cylinder Barrel

The cold-drawn seamless tube is used as a material for the cylinder barrel. Its function is to contain the pressure within the barrel.

The inner surface of the hydraulic cylinder is perfectly machined, and its surface finish should be between 4-16 microinches. This surface finish will reduce the friction between the piston and cylinder.

So, it creates a free upward and downward movement of the piston. If the surface finish of the cylinder barrel is not so good, then there will be more friction between the piston and cylinder.

Hence, there will be chances to damage piston seals due to the continuous movement of the piston within the cylinder.


The function of the hydraulic cylinder base is to contain the pressure from the other end of the cylinder barrel. This hydraulic cylinder base is also called a rod end.

With the help of welding, bolting, or threading, it is connected to the cylinder. It also plays the role of cylinder mounting parts, which mount the devices such as a clevis, the cap flange, and the cap trunnion.

Cylinder Head/End Cap

The other end of the cylinder cap is called as cylinder head. This cylinder head is also called an end cap or blind end. It is attached to the barrel using threading, bolting, or using tie rod.

A static seal is generally used between the cylinder head and cylinder barrel. It has an integrated rod sealing arrangement or an option for a seal gland, which helps to keep the pressure within the cylinder.


The function of the piston in a hydraulic cylinder is to create different pressure zones within the barrel. Its materials are cast or ductile iron and machined in such a way that groves on the piston fit the metallic seal or bearing element.

These seals can be double-acting or single-acting. The extension and retraction of the hydraulic cylinder depend on the pressure applied on either side of the piston.

One end of the piston is attached to the piston rod by threading or bolting to transfer the liner motion.

Piston Rod

The material of the piston rods is hard chrome plated cold rolled steel. It is also referred to as a cylinder rod. This piston rod is attached to the end of the piston by bolting or threading.

Seal Gland

The seal gland is made up of five different seals. These seals are the primary seal, the secondary seal, the bearing elements, the wiper, and the static seal.

Its function is to prevent the leakage of the pressured oil between the rod and the cylinder head. The hydraulic cylinder with a seal gland can easily change or replace all seals as per the requirement to prevent leakage problems.


The seals are one of the essential parts of the hydraulic cylinder. To make a seal of the seal gland, we need to consider many factors such as operating pressure, temperature, piston speed, and application.

The seal in a hydraulic cylinder that works under low temperatures is an elastomer seal. These elastomer seals are made from nitrile rubber.

The hydraulic seal, which works under very high temperatures, uses Fluorocarbon Viton material seals. The wiper and scraper seals are used to eliminate foreign particles, such as dirt and water, which will cause damage to the hydraulic cylinder walls.

The metallic seal is made of bronze and is used in the hydraulic cylinder.

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