What Are Hydraulic Seals?

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What Are Hydraulic Seals?

01 lip 2022, 2:58

What Are Hydraulic Seals?
Hydraulic cylinders are commonly found in industrial machines. Consisting of an actuator, it uses hydrostatic energy to generate force. Hydraulic cylinders essentially use fluid to create a pull or push force. Because they contain fluid, however, they require the use of seals. There are hydraulic seals found in most hydraulic cylinders. What are hydraulic seals exactly?

Overview of Hydraulic Seals

Hydraulic seals are gasket-like rings that are designed to seal areas between the components in a hydraulic cylinder. Hydraulic cylinders contain many different components, some of which are exposed to the fluid. To prevent fluid from leaking around these components, hydraulic seals are used. Hydraulic seals are designed to fit the components in a hydraulic cylinder while creating a leak-proof seal around them.

Hydraulic seals are essentially o-rings. However, they feature a groove within the lip that allows them to fit the components with which they are used. The groove will slide over the component to create a leak-proof seal. Even when the hydraulic cylinder’s piston moves and its fluid pressurizes, the component won’t leak. The hydraulic seal will keep the fluid within the appropriate container so that it doesn’t leak around the component.

Hydraulic Seal Materials

You can find hydraulic seals available in several materials. Rubber is a common material used for hydraulic seals. Rubber hydraulic seals are elastic, resistant to cracking, and long-lasting. There are also polyurethane hydraulic seals. Polyurethane hydraulic seals feature many of the same qualities as those made of rubber, but they are typically stronger and better protected against wear. While not as common as rubber or polyurethane, some hydraulic seals are made of polytetrafluoroethylene (PTFE). PTFE is a synthetic material that’s flexible, strong and resistant to extreme temperatures.

Composite Centrifugal Pump Wear Rings
Pump Composite Wear Ring Key Features

Pump wear rings are simple components, but they have a profound impact on pump reliability, efficiency, and safety.

Most centrifugal pump designs include replaceable rotating wear rings on the impeller (impeller wear rings) and stationary wear rings inside the casing (case wear rings). The wear rings in a pump serve three key purposes:

Create the contact area between rotating and stationary parts inside the pump

Reduce internal recirculation from pump discharge to pump suction or between stages

Create hydraulic forces which stabilize the pump rotor

The wear ring running clearance impacts pump discharge pressure, flow, efficiency, power consumption, vibration, and cavitation. Using composite wear rings with reduced clearance has a positive impact on all these factors.

Composite Centrifugal Pump Wear Ring Advantages

Long-term, large-scale field studies have shown that composite materials can improve pump life by up to 100%, reduce vibrations, and reduce seal leaks. Field tests and pump test stands have shown that reduce clearance can improve pump efficiency anywhere from 2-5% for typical process pumps. Additional pump composite wear ring material benefits include:

Eliminating the metal-to-metal contact points essentially eliminates the risk of galling or seizure

The wear rings will not seize or gall during slow roll or alignment

The pump will have a better tolerance of run-dry events and other process upsets, with a chance of surviving extended off-design conditions

Lower vibration due to improved damping at the wear rings

Fewer seal leaks due to reduced pump vibration and reduced shaft deflection due to tighter wear ring clearance

Higher efficiency due to lower leakage losses across the wear rings

Guide Rings | Wear Rings
The guide ring or wear ring guides a hydraulic cylinder piston and rod and absorbs lateral forces. Metal to metal contact between the moving parts of the cylinder, for instance between the piston and the cylinder or the rod and the cylinder head. The advantages of these non-metallic guide rings (compared with traditional metal guide rings) are, among others, a high bearing load capacity, the elimination of local stress concentrations, wear resistance, a low coefficient of friction, and low maintenance costs.

Advantages Guide Ring

The tapes can be supplied either cut to length or by the meter, to be cut according to requirement.

High load capacity (compressive strength), low wear, and reduced friction due to an additive of carbon to the PTFE material.

No tendency to stick-slip in the case of low sliding speed.

Available in practical dimensions.

Simple groove designs.

Simple piston designs without metallic contact of the sliding surfaces.

Profile geometry is exactly suited to work in lubricated air as well as dry and oil-free air.

Guide strips
SKF guide strips are made of PTFE as standard and should only be used in light-duty applications or when fluid, temperature, friction, or speed do not allow any other material. They are typically used with PTFE sealing systems.

PTFE guide strips are available with different designs and can be cut with different configurations.

Guide strips cut to length

Based on the hardware dimensions, SKF can supply guide strips with specified lengths. They are designated according to a system that states the type and design, dynamic diameter, housing groove diameter, housing groove width, type of cut, and material.

Guide strips uncut

SKF can also supply uncut guide strips. They are designated by the type and design, guide strip thickness t and housing groove width in millimeters, material code, and length in meters, such as SB 2x8,1-292 / 25 m.

Bushings also called flexible or anti-vibration mountings, allow parts to move without transmitting vibration to the cabin. Limited-motion joints, like control arms and sway bar links, usually use bushings. Bushings are also used in non-moving parts, such as body mounts and strut mounts.

Some bushings are filled with oil, and others may be molded to be softer or harder in one direction. The simplest bushing consists of a metal inner sleeve bonded to an outer metal sleeve with rubber. On control arms, like those in the front end, the outer sleeve is pressed into the control arm, and a bolt affixes the inner sleeve to the frame. Neither sleeve moves, but the flexible rubber allows a limited range of motion between them. Rubber doesn’t transmit vibrations well, which prevents them from reaching the cabin.


Body mounts, engine mounts, sway bar bushings, steering rack bushings and sway bar link bushings are usually replaceable without special tools. Some control arm bushings are available separately, but special tools are required. Some control arm bushings are not available separately and require a whole new control arm. Bushings that improve performance are also available in the aftermarket. For example, stiffer bushings can reduce body roll and improve stiffness.

When replacing bushings, two factors are important: First, pay close attention to the depth and orientation of pressed-in bushings. Bushings that are pressed in too shallow or deep can lead to interference and noise, and certain bushings need to be installed in a specific orientation for consistent performance. Second, for control arm, sway bar, shock and strut bushings, tighten all fasteners with all four wheels on the ground. This will prevent preloading the suspension, which can mimic alignment problems.

While bushings are a simple component, replacing them can significantly improve the quality of your ride. Whether you’re replacing bushings for wear or as an upgrade, you can enjoy a quieter and stiffer ride in just a few hours.

What Are Bearings? Let's learn about the basic functions of bearings!
Bearings are "parts that assist objects' rotation". They support the shaft that rotates inside the machinery.

Machines that use bearings include automobiles, airplanes, electric generators, and so on. They are even used in household appliances that we all use every day, such as refrigerators, vacuum cleaners, and air-conditioners.

Bearings support the rotating shafts of the wheels, gears, turbines, rotors, etc. in those machines, allowing them to rotate more smoothly.

In this way, all sorts of machines require a great many shafts for rotation, which means bearings are almost always used, to the point where they have become known as "the bread and butter of the machine industry". At first glance, bearings may seem like simple mechanical parts, but we could not survive without bearings.

Bearings play a crucial role in our daily lives, but it is precise because of their importance that we must constantly strive to make them more precise and durable.

Additionally, it is vital to the development of machine technology that we continue going forward to develop bearings that can work under ever harsher and more specialized conditions.

Bearings will no doubt continue to evolve and change, and improve our livelihoods by "making the world go round".


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