With the extensive range of shock absorbers produced, there is a shock absorber to fit every driving style and application. The enormous choices available, however, can also become an annoying stumbling block to a buyer. Hence, we’ve come up with this guide to enlighten you on the function of a shock absorber and simplify your selection process.
Let’s begin at the top.
What is a shock absorber? What does it do?
If you drove over a speed bump without a shock absorber, your car would keep vibrating up and down as a reminder that you just went over the speed bump. That's why cars need shock absorbers—to dampen or reduce the effect of vibration on the vehicle. The spring system used in the shock absorber helps to rapidly restore the smooth ride after climbing over a bump or entering into a pothole.
In more technical terms, a shock absorber (also referred to as shocks) is a sophisticated mechanism that reduces (or dampens) vibration by absorbing shocks. Doing so, it guarantees constant contact between the wheels and the road surface during motion. This part of the vehicle, which is a vital component of the car's suspension system, is also designed to compensate for the weight on the chassis. It becomes all the more critical when plying a bumpy road. It is installed very close to the wheel on the inside.
How does the shock absorber work?
Loads—shocks and vibrations—are transmitted from the wheel to the shock absorber through a lever system. The shock absorber is equipped with a spring around it, which provides a quick return after the vehicle hits a bump. Without it, the comfort of the passengers would be compromised, as I said early on.
Bumpy road or not, your vehicle’s overall handling depends on the condition of the shock absorbers. Here’s why? When the car accelerates, the vehicle’s body leans back, and the load in the front of the car lessens. This load shift affects the contact between the front wheel and the road. When braking, a reverse of this process occurs. Therefore, without the shock absorbers, it would be relatively challenging to control the vehicle during these load shifts.
So whether you’re travelling a smooth road or a bumpy one, you still need a shock absorber.
How many types of shock absorbers are there? What are they?
Shock absorbers are categorised into three types based on the working fluid utilised in them.
1. Hydraulic: These types of shock absorbers have oil in their reservoir. This oil, under the action of the piston, flows from one level of the pool to another.
2. Gas-hydraulic: This is also called gas-oil. In the design of this variety, the compensation chamber is occupied with gas and oil. Gas-hydraulic type shocks are notable for helping to limit the likelihood of damage to the bottom part of the absorbers due to extreme load.
3. Gas: In these types, the gas used in the cylinder under pressure is also used as a damper.
Shock absorbers are also categorised into four types according to their damper mechanism, namely:
1. Two-pipe types of shock absorber: This is the most common category of shock absorber around today. They consist of:
- A case which contains the flask – in the space between the walls of the case and the flask is a gas and compensation cavity.
- The flask which is wholly filled with a shock-absorbing fluid
- The rod pushing the piston
- The piston equipped with check valves opening alternatively upon the movement of the piston
In this mechanism, the stabilisation of rebound forces occurs due to the operation of the piston and valves.
2. Monotube or Single Tube Shock Absorber: This type of shock absorber consists of:
- A flask that is partially filled with gas and oil (Although some monotubes are completely gas filled)
- A rod that moves the main piston
- The piston mounted on the rod which is equipped with bypass valves which the valve flows through
- A separation piston, separating the oil chamber from the gas chamber (this part would not be present if the model is gas-filled)
The piston in this mechanism does not reach the bottom of the cylinder. This reduces the possibility of penetration of the shocks on large bumps.
3. Combined Shock Absorbers: This is a modification of the two-pipe type. The design is also called gas backwater and allows better controllability of the vehicle. The gas support serves as additional support, increasing the effectiveness of the rack.
4. Adjustable Shock Absorbers: These types are installed on luxury and expensive cars with the function of selecting the road surfaces. These are almost identical to the two pipe modifications, except that they have an additional reservoir. Electronics monitor parameters of the absorber and adjustments are made on the inside of the absorbers using control knobs to suit different terrains. The different types of settings available on this absorber are:
How do I choose the best shock absorber for my car?
Again, every shock absorber has its pros and cons. Every shock absorber has conditions it is best suited for. For instance, soft model shock absorbers generally provide increased comfort during rides. At the same time, they reduce the grip of the wheel to the road. In comparison with hard models, the stability of the car is increased, but the comfort is a bit lower.
More often than not, the “perfect” option is simply the option recommended by the car manufacturer. In exceptional cases, your mechanic can suggest a more appropriate type based on his evaluation of your car and driving conditions. That said, when choosing a shock absorber, pay attention to the following:
1. Cost – Gas absorbers are more expensive than oil absorbers.
2. Comfort and durability – The gas models are believed to provide less comfort during rides. However, they last longer than the oil models. For more info, please check out our article on the longevity of shock absorbers.
3. Handling of the car – The gas model is ideal for racing and sports because it ensures stability and grip. Oil models are designed for measured rides.
By Damilare Olasinde