In my journey through the world of hydraulic systems, I have discovered that the right hydraulic cylinder seal is crucial for optimal performance and longevity. However, there are several types of seals that are often overlooked or not widely discussed. Understanding these six types of hydraulic cylinder seals can significantly impact efficiency and prevent costly leaks or failures. In this article, I will share insights into these lesser-known seal types, highlighting their unique features and applications to help you make informed choices for your hydraulic systems.

Construction machinery is inseparable from the oil cylinder, and the oil cylinder is inseparable from the seal. A common seal is a sealing ring, also called an oil seal, which acts as a barrier against oil and prevents oil from overflowing or passing through.

Common sealing rings used in hydraulic cylinders are of the following types: dust ring, piston rod sealing ring, buffer sealing ring, sound guide support ring, end cover sealing ring, and piston sealing ring.

1. Dust Ring

The dust proof ring is installed on the outside of the end cover of the hydraulic cylinder to prevent external contaminants from entering the cylinder. According to the installation method, it can be divided into a snap-in type and a press-in type.

The Basic Form of The Snap-in Dust Ring

The snap-in dust ring is the most common, as the name suggests, dust ring: it is stuck in the groove on the inner wall of the end cover and is used in less harsh environmental conditions. The material of the snap-in dust ring is usually polyurethane, and there are many variations of the structure, such as the H and K cross-sections with double lip structure, but they are inseparable.

Some Variants of The Snap-in Dust Ring

The in-type dustproof ring is used under severe and heavy load conditions. It is not stuck in the groove but is wrapped with a layer of metal to increase the strength of the polyurethane material and pressed into the end cover of the hydraulic cylinder. There are also many types of press-in dust rings, which are also divided into the single lip and double lip.

2. Piston Rod Seal

The piston rod seal is also called a U-shaped cup, which is the main piston rod seal, installed inside the end cover of the hydraulic cylinder, to prevent the hydraulic oil from leaking. The piston rod seal ring is made of polyurethane or J nitrile rubber. In some cases, it needs to be used with a support ring (also called a retaining ring). The support ring is used to prevent the seal ring from being squeezed and deformed under pressure. There are also many variants of piston rod seals.

Common Forms of Piston Rod Seals

3. Buffer Seal

The buffer seal is used as an auxiliary piston rod seal to protect the piston rod when the system pressure suddenly increases. There are three common types of buffer seals. Type A is a single-piece sealing ring made of polyurethane. Type B and Type C are two-piece, used to prevent seal extrusion and allow the seal to withstand higher pressure.

4. Guide Support Ring

The support ring is installed on the end cover of the hydraulic cylinder and the piston to support the piston rod and the piston, guide the piston to move linearly, and prevent metal-to-metal contact. There are plastics, bronze coated with PTFE, etc. on the materials.

5. End Cover Sealing Ring

The end cover sealing ring is used to seal the oil red end cover and the oil red wall. It is a static seal to prevent hydraulic oil from leaking from the gap between the end cover and the cylinder wall. It is usually composed of a nitrile rubber O-ring and a support ring.

6. Piston Seal

The piston seal ring is used to isolate the two chambers of the hydraulic cylinder and is the main seal in the hydraulic cylinder. Usually two-piece, the outer ring is made of PTFE or nylon, and the inner ring is made of J nitrile rubber. There are also many variants, including the use of bronze coated with PTFE, etc. On single-acting cylinders, there are also polyurethane U-shaped cups.