car shock absorber
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Auto parts manufacturers make different types of shock absorbers. The kind to use in a vehicle depends on many factors.

Car shock absorbers control the movements of suspension springs. This helps improve the quality of rides and enhances vehicle stability. Shocks also prolong the life of tires and other suspension components.

In this article, we will look at the different types of shock absorbers and the parts that make them.


Different Types of Shock Absorbers

The automotive shock absorber has evolved over the years to become the type used today. There are pneumatic or air shocks and hydraulic shock absorbers.

Air shock absorbers dissipate the energy of suspension spring action by exhausting the heated air into the atmosphere.

In hydraulic shock absorbers, a viscous fluid is heated. Because the fluid cannot leave the tube, the heat generated conducts away through the body of the shock.

Hydraulic shock absorbers are the most common shock absorber types- and the subject of this article.

We also have standard and heavy duty shock absorbers. Standard shocks fit the requirements of many motor vehicles. Heavy duty shocks feature studier constructions, better quality oil, more robust seals, and several other advantages.

Here are the different types of shock absorbers used in modern automobiles. They are classified according to design and working principle.

1. Twin Tube Shock Absorbers

twin tube shock absorber

As the name suggests, twin tube shocks consist of two different tubes: the outer tube that forms the body of the shock and an inner one inside of which the piston moves.

Valves between the two tubes and holes in the piston facilitate the movement of oil when the shock is working. 

Twin tube shocks are the most common of all shock absorber types. They are also among the most affordable.

You will find these shocks in most cars and trucks.

Despite the advantages of low cost, twin tube stocks have their downsides when used in a vehicle.

Among the disadvantages is their ineffectiveness in severe road conditions.

If the road is too bumpy, the rapid movements of the piston cause the shock absorber oil to overheat.

The hot oil then becomes aerated and bubbly, a situation that results in a reduction of the shock’s ability to control spring oscillation.

The heavy duty version of twin tube shocks features studier parts and higher quality hydraulic fluid.

When used in a vehicle, the limitations of oil foaming may not occur easily.

However, that would only be possible when driving on normal roads. Long rides over roads with severe imperfections would give rise to the problem.

2. Mono Tube Shock Absorbers

mono tube shock absorber

A mono time shock comprises a single tube. Inside the tube is a piston and shock absorber hydraulic fluid. The tube of these types of shocks is directly exposed to the atmosphere.

Mono tube shocks have their advantages and downsides.

Compared to twin tube shocks, mono tube shocks absorbers are more costly to make. They are, therefore, not as common in motor vehicles. These shock types dissipate heat better owing to their body being exposed to the air.

Gas Filled/Mono Tube Shock Absorbers

Most modern shock absorbers are of this type.

Gas filled shocks consist of a gas, usually nitrogen, to prevent the hydraulic oil from foaming. The gas is injected into the shock absorber tube during manufacture and the point of injection sealed off.

Gas filled shocks do not lose effectiveness when the piston moves rapidly through the oil to cause excessive heat.

They are, therefore, suitable for off-road motor vehicles that drive over long stretches of uneven roads. They are also commonly used in racing cars.

The advantages of gas filled shock absorbers come at a price. They are one of the most expensive due to the need for tight clearances in the tube. Gas filled shocks should not be confused with “air shocks.”

Air shocks use a separate chamber containing air as the hydraulic oil.

In these shock types, a valve delivers air into the gas chamber to lower or raise the vehicle body during the shock absorber operation.

3. External Reservoir Shock Absorbers

external reservoir shock absorber
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These are state-of-the-art shocks. External reservoir shocks feature a different design from the other types.

Essentially, they comprise a compact and lightweight construction with tight clearances. The shock absorber body is connected to an external hose.

The hose transmits hydraulic oil to the shock from a separate reservoir, which can be remotely located or attached to the shock. The design has several advantages.

Having the shock absorber oil in a separate chamber helps reduce the amount of weight pressing down on the wheels.

There is ample space for the expansion of shock oil, which helps to protect the shock absorber components from pressure.

Because the oil is held in another part of the shock absorber system, external reservoir shocks cool down more rapidly than the other types.

External reservoir shocks are manufactured for high-performance applications such as rally cars.

They are expensive and may not make economic sense to use in ordinary automobiles.

Coil Over Shock Absorbers

These are a popular design and used in many vehicles.

Coil over shocks, as the name suggests, feature a spring coil surrounding the shock absorber body.

A coil spring shock absorber offers many advantages.

The coil helps to enhance the working action of the shock, making the device one of the most effective. Coil spring shock absorbers can also be adjusted. They can be lengthened or collapsed to suit the preferred ride height.


Parts of a Shock Absorber

Although shock absorbers differ in design and operation, the main parts remain similar. Here is a shock absorber parts diagram showing the components that make the external and internal sections.

Parts of a Shock ABsorber
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Shock Absorber Parts Name and Function

Shock Absorber Mounts

Shock absorber mounts are parts that secure shocks to the vehicle body and suspension. There is the upper and lower mount. Both of these can be of the same design, featuring an “eye into” which a bushing and bolt are inserted.

A popular design is to have an “eye”  for the lower mount and a “pin” for the upper mount.

Shock Absorber Bush

These are located on the mountings. Usually made of rubber or urethane, bushings absorb vibrations and separate metal parts to prevent noise and wear. Bushings are among the shock absorber components that can be replaced.

Shock Absorber Coil Spring

Some shock absorber types feature a coil spring as part of the shock absorber assembly. These are commonly known as coil over shock absorbers or spring coil shock absorbers.

Although this type of shock looks like a suspension strut, it should not be mistaken for one. 

Shock Absorber Piston and Piston rod

The shock absorber piston contains valves or openings. The working of the shock revolves around the movement of oil through these passageways.

The piston rod part guides the piston inside the shock absorber cylinder.

Shock Absorber Cylinder

This is the tube that forms the body of the shock absorber. It contains the compression oil and forms the tube inside which the shock absorber piston moves.

Shock absorber bolts

The fasteners that hold the shock to the body of the vehicle on one end and suspension at the other end. These must be torqued to the right torque values. Under torquing can cause loose shocks that do not work as expected.

Other major car shock absorber parts include:

Oil seal- the seal that prevents the oil on the shock absorber tube from leaking out during operation. It also prevents contamination from entering the tube.

Oil guide- an oil passageway to ensure smooth operation of the shock absorber

Rod guide- providesfor the smooth movement of the piston rod.

Nitrogen gas and gas chamber- a gas contained in a chamber within the compression chamber or cylinder. It prevents bubbles from forming in the oil.

Washers and plates- spacersthat form an important part of the shock absorber parts.


What is Shock Absorber Bush and How Does it Work?

shock absorber bushing
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A shock absorber bush is the part that forms the interface between the shock mount and the body of the vehicle.

It prevents the metal parts from coming into direct contact.

The bushings also help to dampen vibrations that result from the vertical movements of the wheels on rough road conditions.

Shock absorber bushings are found at either end of the device.

The bushes are made a rubber material but mostly synthetic rubber called polyurethane. Rubber shock absorber bushes have the advantage of offering softer cushioning and reducing vibrations and noise better.

 Polyurethane shock absorber bushings, on the other hand, are firmer and offer better feel. They also last longer than rubber bushings. However, polyurethane bushings require greasing, unlike the rubber types.

When it comes to installation, rubber bushing shock absorbers need a skilled person to avoid damage. Mounting a urethane shock absorbers can be DIY job.

Bushings are prone to wear due to the constant movements of shocks.

When that happens, signs of worn bushings start to show.

The symptoms are more or less similar across all shock types, from motor cycle shock absorber bushes front bushes to rear shock absorber bushes of cars and trucks.

They include excessive bounce and vibrations.


What are Shock Absorber Mounts and How Do They Work?

Shocks attach to the chassis at one end and the axle on the other.

A shock absorber mount secures the shock absorber to the vehicle.

The mount can be the “eye” type or “pin” type. “Eye mounts” feature an opening and a bolt that goes through it. The “pin” mount consists of a threaded shaft onto which a nut fastens.

Shock absorber mounts have a lifespan and will eventually wear out. Worn shock mounts present vehicle drivability problems, make a car unsafe to drive, and rides uncomfortable.

Luckily, these parts are replaceable. Their changing can even be a do-it-yourself project if you have the shock absorber mounting kit.

The kit contains all the components needed to change mounts.


Conclusion

Shock absorbers perform crucial functions in the car suspension system.

It is essential to understand the different versions of these auto parts. Also, the components they are composed of.

The information contained here should be a starting point.

It is meant to make you conversant with the types of shock absorbers used in today’s motor vehicles.