Shock Absorbers

Shock Absorbers

For the smooth running of your car, a lot of action goes on underneath. Taking center stage in your car's hydraulic system is what we call dampers or in other words shock absorbers. But what makes them such a fuss for your vehicle's needs?

Role of a Shock Absorber

Simply put, a shock absorber is a hydraulic device that absorbs impulses from your car's suspension and spring. It reduces the recoiling factor that occurs when driving on a bumpy road. Contrary to belief, a shock absorber doesn't aid in weight support. It, however, is in charge of maintaining wheel contact on the road at all times. Your damper does this by resisting upward motion through viscous friction.

How shock absorbers work

In its basic form, a shock absorber works like an oil pump located between the wheels and the car frame. The upper mount of the damper joins to sprung weight (car shell supported by the springs) while the lower mount connects to the unsprung weight (wheel axle).

In the conventional twin-tube shock absorber (a design that features two tubes in the hydraulic fluid chamber), the upper mount contains a piston rod that is connected to a piston located inside the hydraulic fluid chamber. This chamber consists of a pressure tube (interior chamber) and a reserve tube (outer chamber).

During bumpy drives, the upper shock mount forces the piston rod down pushing the piston further in the pressure tube. The tiny opening in the pressure tube let out small amounts of hydraulic fluid under high pressure into the reserve tube. The resistant flow is what brings about the slowdown of the damper hence a stop in the spring oscillation.

A shock absorber thus converts the kinetic energy generated by your car's spring constant expanding and contracting into heat (thermal) energy. It then disposes of the heat energy to the atmosphere through heat exchange.

A shock absorber works in two cycles: compression and extension. During compression, the piston moves down while in extension state, it moves up the pressure tube. With that said, the compression cycle is in charge of the movement of your unsprung weight (wheel effects during a bump) while the extension cycle is left to handle the motion of the sprung weight (your car's body).

Types of Shock absorbers

Today's shocks are design with motion-sensitive capability – how fast your spring action is and the resistance your shocks need to provide. This advancement makes shocks adjustable to different road conditions thereby controlling unwanted motions that result from bouncing, swaying, braking, and accelerating.

The types of shocks available also differ mostly in terms of design and application. They include:

  • Standard Shock: It's the conventional oil-filled damper that can last for 100,000 miles before needing replacement. This shock, however, features no special effects. It's commonly adorned by 20th-century cars.
  • Gas Shock: It's often used on smaller vehicles. It relies on oil for cushioning while the pressurized nitrogenous gas found inside is used to keep the oil from foaming or thinning out when cooling the shocks.
  • Coil-over/overload Shock: Highly used on off-road cars such as drifters and drag racers. They mostly feature coil spring fixed around the shock cylinder.
  • Heavy Duty Shock: Used on trucks, passenger buses and any vehicle that carries extra weight. They come with reinforced attachments points, larger diameters, and bigger center shafts.
  • Automatic Lever Control Shock: Found on high-end cars. Comes with electric operated air pumps that automatically adjust in case there is added weight.
  • Air Shock: It's an aftermarket shock that's generally installed in the rear tires of trucks and vans. Comes with an air inlet that pressurizes the shock for a raised vehicle. Unlike the automatic control shock, this must be manually inflated.

How to identify a damaged shock absorber

After years of use, your shocks tend to wear out. When they do so, they are certain alarms that you need to watch out for, they include:

  • Oil leaks: Oil stains are alarming. If noted, it's best to change your shocks asap.
  • Rocking and rattling: Worn out shocks can cause a bouncing effect making the ride very uncomfortable. The constant rocking also affects wheel contact with the ground. Driving under such conditions makes maneuvering difficult.
  • Swerving and nose dive: Your shocks keep your car steady during brakes and accelerations. If damaged, your front tends to dive when braking while the rear squats during acceleration. Your vehicle's stability may also be compromised during turns. The car's body may feel like its leaning towards the bend.
  • Long stopping distances: Damaged shocks can increase your stopping distance by 20%. As you continue to accelerate the longer the distance, it will take to stop when suddenly braking. This is quite dangerous in case of an accident.
  • Uneven tire wear: As mentioned earlier, shocks keep your tires even on the ground. If damaged, uneven road contact is established, and the result may be fast wear-outs on some tire parts. This may result in punctures or hydroplaning.
  • Vibrations: One major red flag is the clucking sound normally heard when driving. The vibrations can also be heard when steering.

If your car is experiencing these indications, it might be time to replace your shock absorber with a new one.





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