What Is Shock Absorber?- Definition, Types, and Parts

What is Shock Absorber?

A shock absorber or damper is a mechanical or hydraulic device used to absorb and damp shock impulses. This is done by converting the kinetic energy of the shock into another form of energy (typically heat), which is then dissipated. Most shock absorbers are some sort of dashpot (a damper that resists motion by viscous friction).

Along with smoothening out bumps and vibrations, the key role of the shock absorber is to ensure that the vehicle’s tyres remain in contact with the road surface at all times, which ensures the safest control and braking response from your car.

What do shock absorbers do?

Shock absorbers essentially do two things. Shock absorbers not only control the movement of springs and suspension but also keep your tires in contact with the ground at all times. At rest or in motion, the bottom of your tires is the only part of your vehicle that comes into contact with the road.

Any time that a tyre’s contact with the ground is broken or reduced, your ability to drive, steer and brake is severely compromised.

How do shock absorbers work?

The shock absorbers dampen the movement of the springs by converting the spring’s kinetic energy into thermal (heat) energy. Shock absorbers are oil-filled cylinders. When your vehicle’s suspension moves, a piston moves up and down through the oil-filled cylinder.

Firstly, a little bit of science. Shock absorbers work by taking the kinetic energy (movement) of your suspension and converting it to thermal energy (heat) that is then dissipated into the atmosphere through the mechanism of heat exchange. But it’s nowhere near as complicated as it may sound.

As mentioned, shock absorbers are basically oil pumps. A piston is attached to the end of a piston rod and works against hydraulic fluid in the pressure tube. As the suspension travels up and down, the hydraulic fluid is forced through orifices (tiny holes) inside the piston.

Because the orifices only allow a small amount of fluid through the piston, the piston is slowed which in turn slows down spring and suspension movement.

Shock absorbers automatically adjust to road conditions because the faster the suspension moves, the more resistance they provide.

Parts of Shock absorber

  • 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” in which a bushing and bolt are inserted.
  • 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.
  • 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.
  • 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.

Types of Shock absorbers

Following are the different types of shock absorbers:

  • Hydraulic type shock absorbers
  • Double acting shock absorbers
  • Single acting shock absorber
  • Friction type shock absorber
  • Lever type shock absorber
  • Telescopic type shock absorber
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1. Hydraulic Type Shock Absorber

Hydraulic type shock absorbers are now used on all passenger cars. They increase resistance to the spring action by forcing a fluid through check valves and small holes.

2. Double Acting Shock Absorber

Double-acting shock absorbers offer resistance both during compression and rebound of the springs.

3. Single Acting Shock Absorber

A single-acting shock absorber offers resistance only on the rebound.

4. Friction Type Shock Absorber

The friction-type shock absorbers have almost become obsolete due to their non-predictable damping characteristics.

5. Lever Type Shock Absorber

The lever-type shock absorber is of indirect-acting type. It is bolted to the chassis through a lever and link. As the axle moves up and down, a double piston arrangement forces the oil through a valve.

6. Telescopic Type Shock Absorber

Telescopic type shock absorber is of direct-acting type. It is mounted between the axle and the frame.

A simplified diagram of the telescopic shock absorber. Its upper eye is attached to the axle and the lower eye to the chassis frame. A two-way valve A is attached to a rod G. Another two-way valve B is connected to the lower end of cylinder C.

The fluid is in the space above and below valve A, and also in the annular space between cylinder C and tube D, which is connected to the space below valve B. The head J has a gland H. Any fluid scrapped off by the rod G is brought down into the annular space through the inclined passage.

7. Twin Tube Shock Absorber

A twin-tube shock absorber consists of an inner and outer cylinder. The inner cylinder contains oil and the piston rod is connected to the piston valve. Whereas the outer cylinder acts as a reservoir and has a low-pressure gas. The flow of oil from one chamber to another is controlled by a base valve.

As the wheel moves up and down, so does the piston rod. The piston valve and base valve confirm the compression and rebound of the absorber. They measure how fast the oil flows back and forth. Vibration and shock are similarly absorbed by low-pressure gas. This gas acts like a balloon and absorbs vibrations.

8. Mono-tube Shock Absorber

These are high-pressure gas shocks having a pressure tube. This pressure tube consists of two pistons, a dividing piston, and a working piston. The installed pistons and rods are similar in design to twin-tube shocks.

A mono-tube shock absorber is mounted upside down or right side up and will work either way. Considering its flexibility, mono-tube shocks with springs are an important component to support the weight of the vehicle.

A mono-tube shock absorber does not have a base valve. The mono-tube shock has a greater surface area and carrying capacity. These are well known because the high amount of oil helps to dissipate heat much faster and reduces fading.

9. Spool Valve

Spool valve dampers are characterized by the use of hollow cylindrical sleeves with machined-in oil passages as opposed to traditional conventional flexible discs or shims. Spool valving can be applied with monotube, twin-tube, and/or position-sensitive packaging, and is compatible with electronic control.

Primary among benefits cited in Multimatic’s 2010 patent filing is the elimination of performance ambiguity associated with flexible shims, resulting in mathematically predictable, repeatable, and robust pressure-flow characteristics.

FAQs.

What does a shock absorber do?

Shock absorbers are critical safety components that can affect tire wear, stability, braking, vibration, driver comfort, and the life of other steering and suspension parts. Shocks work with a commercial truck’s suspension system to maintain tire-to-road contact by controlling spring movement.

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How do I know if my shock absorbers are worn?

4 Symptoms of Worn or Failing Shock Absorbers

  • Excessive Bouncing, Swerving, & Diving.
  • Uneven Tire Wear.
  • Longer Stopping Distance.
  • Steering Wheel Vibration.

Is it safe to drive with a broken shock absorber?

The short answer is no – you should not drive a car with a broken suspension. Regardless of whether it’s a broken coil spring or a broken shock absorber, you cannot drive a vehicle that has an element of the suspension that is broken.

How long do shocks last?

On average, if your car has been “babied,” you can expect your shocks/struts to last about 10 years. If you have really used your car as a workhorse, 5 years is probably all you can expect. This means that for the average driver, 7 or 8 years is the maximum life expectancy of most shocks and struts.

Do shocks have oil in them?

Shock absorbers are small oil pumps with a piston inside. They’re filled with oil and usually have a rod that goes through the top of the shock. The top of the shock has a seal that stops any leakage, but this can get damaged, and the oil leaks out over time.

What do worn out shocks sound like?

Unusual noises – When shocks and struts are worn out you may hear a clunking or knocking sound. This sound is caused by metal-to-metal contact when the shock or strut bottoms out when hitting a bump. In addition, these noises could be a result of worn shock or strut mounting components.

What happens if shocks are bad?

Bad shocks also can affect steering control and cause uneven tire wear. Because car shocks wear out gradually, you might not notice because you get used to looser, bouncier ride quality, much like you get used to longer stopping distances as brake pads on your car wear out.

How often do you need to replace shocks?

Like all other automobile parts and systems, shocks and struts have a specific maintenance schedule. Auto repair experts say that generally they should be replaced between every 50,000 to 100,000 miles, depending on how much wear and tear they have received.

Can you replace just one shock absorber?

Your shock absorbers work in pairs, so ideally, replacing both of them should be carried out at the same time. However, if one has broken, or is severely damaged, you could consider replacing only the damaged side.

How do I know if my car needs new shocks?

The Warning Signs of Worn Shocks and Struts

  • Instability at highway speeds.
  • Vehicle “tips” to one side in turns.
  • The front-end dives more than expected during hard braking.
  • Rear-end squat during acceleration.
  • Tires bouncing excessively.
  • Unusual tire wear.
  • Leaking fluid on the exterior of shocks or struts.

What causes shocks to bend?

Loading more weight into a vehicle than it is rated to carry can cause the struts supporting the car to bend. However, even if a car is near, but not beyond, its maximum payload, potholes or other flaws in the road can bounce the vehicle. This bouncing can cause weight shifts inside the vehicle that can bend struts.

Are shocks in the front or rear?

In fact, most modern vehicles have struts on the front axle and shocks on the rear axle. You might have struts on both axles, but it is rare to have only shocks.

How much is it to replace shocks?

To replace the shocks on the same axle, on average, it will cost you between $250 and $600 for parts, while labor costs will be somewhere between $150 and $350.

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What’s better gas or oil shocks?

Gas-charged shocks provide a sportier ride. must compress before the oil can be forced through the valve. Hydraulic shocks give a softer and smoother ride. is increased at a slower in the hydraulic shocks which produce the softer feel.

What are car shocks filled with?

Shocks are simply tubes filled with hydraulic oil and attached to a piston, a device that allows the shock to release small amounts of hydraulic oil under great pressure to relieve the vehicle’s bouncing movement.

What fluid is in a shock absorber?

The shock absorbers dampen the movement of the springs by converting the spring’s kinetic energy into thermal (heat) energy. This thermal energy has then degenerated in hydraulic fluid. Shock absorbers are oil-filled cylinders.

What is the purpose of a shock absorber?

Shock absorbers are critical safety components that can affect tire wear, stability, braking, vibration, driver comfort, and the life of other steering and suspension parts. Shocks work with a commercial truck’s suspension system to maintain tire-to-road contact by controlling spring movement.

What is shock absorber material?

Shock absorbers and dampers are generally made of high-strength steel to handle the pressures from the internal hydraulic forces. Elastomeric seals prevent the fluid from leaking out of the cylinder, and special plating and coatings keep the units protected from harsh operating environments.

What are the types of shock absorbers?

Following are the different types of shock absorbers:

  • Hydraulic type shock absorbers.
  • Double acting shock absorbers.
  • Single acting shock absorber.
  • Friction type shock absorber.
  • Lever type shock absorber.
  • Telescopic type shock absorber.

What are shock absorbers in a car called?

More accurately called dampers, “shocks” damp excessive motion, keeping the vehicle’s body from bouncing down the road.

What happens if shock absorber breaks?

A broken shock absorber will result in your car bouncing around, as well as excessive rolling, squatting, and diving. In other words, it won’t be comfortable. Plus, your car will be harder to control, especially at high speeds.

What is the difference between shock absorber and suspension?

As far as shocks also referred to as the shock absorbers, are a key component of the suspension system. They control the impact and rebound movement of your vehicle’s springs and suspension; they ensure that the vehicle’s tires remain in contact with the road surface at all times. ultimately, they absorb energy.

How do shock absorbers work?

Where is the shock absorber?

How long do shocks last?

On average, if your car has been “babied,” you can expect your shocks/struts to last about 10 years. If you have really used your car as a workhorse, 5 years is probably all you can expect. This means that for the average driver, 7 or 8 years is the maximum life expectancy of most shocks and struts.

Can shock absorber be repaired?

Not every shock absorber problem can be repaired. Parts that you can replace individually include mounts, shock absorber bushings, seals, pistons, and compression oil. As a rule of thumb, you should only consider shock absorber repair if the existing shocks have not done more than 35 000 miles or slightly more.

Can you drive a car with a damaged shock absorber?

The short answer is no – you should not drive a car with a broken suspension. Regardless of whether it’s a broken coil spring or a broken shock absorber, you cannot drive a vehicle that has an element of the suspension that is broken.

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