Three Types of Hydraulic Seals

04 Nov.,2022


high pressure hydraulic seals

Hydraulic Seals are widely used in hydraulic machinery. They serve to seal openings between component parts. Most hydraulic seals are soft, non-metallic rings that sit in grooves or are fixed rings.

Seals are crucial to powering hydraulics. They decrease the loss rate of liquids in hydraulic machines. As such, the seals are essential to running the machinery.

Three of the most common hydraulic seals include piston seals, rod seals, and RFD rod seals.

Piston Seals

Piston seals for hydraulic machines block fluid from passing through the piston as it drops into the cylinder. These dynamic hydraulic seals come in several varieties:

Single-Acting Piston Seals

Single-acting piston seals work in one-directional, displacement-type hydraulic cylinders. These seals cover only the one side where pressure applies.

Single-Acting Cylinders use gravity or a spring to move the rod and return it to its resting position. Vehicle hoists serve as typical examples of single-acting cylinders.

The environment where the single-acting piston is deployed must consider when selecting the seal. For example, many single-acting cylinders supply hydraulic oil to only one side of the piston, leaving the opposing side exposed to the atmosphere. In these cases, the open side of the cylinder draws air that frequently carries contaminants. Therefore, selecting a seal rated to handle the external environment is vital.

Double Acting Piston Seals

Double-acting piston seals close two opposing sides of a piston. Usually, double-acting piston seals contain a slide ring and an energizer. The elastomeric energizer provides enough force to keep the slide ring in sealing contact with the cylinder bore.

Double-acting cylinders typically contain the same fluid on both sides of the piston. Because of this, thick lubrication films can be used between the piston seal and the cylinder bore to minimize wear and tear.

Pressure from both sides is needed to force the piston along the bore. Because of this, adequate protection requires a double-acting seal that applies pressure from both sides. However, in some cases, two single-acting seals arranged back-to-back can create a double-acting seal system.

Rod Seals

The efficiency of hydraulic machines depends on rod seals efficient hydraulic system. Rod seals prevent hydraulic cylinder leakage and protect the cylinder from dirt and other exterior contaminants.

Types of Rod Seals

  • RFD Rod Seals

RFD rod seals serve as heavy-duty seals. Manufacturers construct them from rubberized fabric.

  • RTA Rod Seals

RTA rod seals function as single-acting seals that are used in hydraulic cylinders. They have small groove dimensions. They work in tandem with NBR O-ring and PTFE inner rings. As a result, they increase sealing resistance to cope with the highest-pressure level.

  • RUB Rod Seals

Rub rod seals are constructed from piston rods. They are single-acting seals with additional O-rings that lubricate and protect against abrasions. Polyurethane Rub seals provide a 300 BAR resistance that has the strength to function in high-pressure systems.

Wiper Seals

Wiper seals frequently work in conjunction with other sealing components. They offer the advantage of allowing ramrods to pass through a seal’s inner bore and prevent leakage.

These seals protect hydraulic operating systems against contamination from outside particles. They function by keeping dirt, moisture, and other damaging elements from damaging cylinder walls, seals, and other key mechanical components.

Wiper seals must be secured to prevent part failures. When they come loose, component failures of the fluid power system and other pieces cause severe damage.

Manufacturers make most wiper seals from polyurethane. They include a secondary lip, which catches any oil that seeps through the main seal. The lip also wipes contaminants from the rod surface.

Hydraulic seals play a key part in the running of hydraulic machinery. They come in multiple varieties, including piston seals, rod seals, and wiper seals. As critical components of hydraulic systems, seals make hydraulic machinery possible.

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