How Does A Shock Absorber Work?
The shock absorber is one of the components of a vehicle's suspension system. The shock absorber is used to reduce the oscillation force from the spring. This damping is done by slowing down the vibration from the spring movement, specifically by converting the kinetic energy into heat energy and released through hydraulic fluids.
If the car's suspension system only has sprung, the vehicle will constantly shake up and down when it receives a shock/impact from the road. It makes the driving experience uncomfortable. Therefore, the shock absorber plays an important role in reducing vibrations and shocks due to the spring's oscillation.
In a vehicle, one side of the shock absorber is attached to the vehicle frame, and the other side is connected to the lower arm component, which is a suspension component that moves freely following the up and down motion of the wheel.
Inside the shock absorber, there is a liquid/fluid known as shock absorber oil. This oil will dampen the vibration of the spring oscillation and convert it into heat energy. In some types of shock absorbers, this fluid is replaced by compressed gas/air but has the same function: to reduce the vibrations that occur due to the oscillatory spring motion.
I. Shock absorber components
For more details, consider the construction of the shock absorber structure in the following image.
In construction, the shock absorber consists of several main components, namely:
- Piston - The piston is a component in the shock absorber tube that moves up and down when the shock absorber works. The piston often has a small orifice hole and a large valve hole where the shock absorber oil flows.
- Piston Valve - functions as an insulator between the upper and lower chambers and a place for shock absorber oil to flow.
- Orifice hole - to slow down the shock absorber oil flow and create a damping effect.
- Tube - used as a place for the piston to move up and down during damping. It also uses as a place for hydraulic oil.
- Piston Rod - Is a connecting rod between the piston and the shock absorber tube, which is attached to the vehicle frame.
II. How does a shock absorber work
The shock absorber works in two duty cycles, namely the compression cycle and the extension cycle. Each cycle works alternately as the spring moves or pushes the piston rod. Read on how the two shock absorber cycles work below.
1. Compression cycle
The compression cycle is a shock absorber work cycle when the piston rod is depressed due to the spring's oscillating force. The pressure that occurs on the piston rod causes the shock absorber to experience a shortening in size so that the length of the shock absorber is shorter than the previous size.
When the compression cycle occurs, the piston will move inward and press the oil in the chamber below the piston. As a result, this depressed oil will flow out into the piston's upper chamber through a large valve hole where the shock absorber oil moves.
Meanwhile, the piston's small orifice will be closed by a valve installed under the piston. The closure of this orifice hole occurs due to oil pressure when the piston presses down.
That way, the shock absorber's current condition is not dampening the suspension spring's oscillating compressive force because hydraulic oil can easily and quickly rise into the upper chamber above the piston through the large valve hole earlier.
2. Extension cycle
The extension cycle becomes the shock absorber duty cycle when the piston moves from the lower back to the up position. This movement will resize the shock length back to its original size.
The return of the piston moving upwards will make the shock absorber oil that is already in the upper chamber of the piston become depressed. On the other hand, this large valve hole will be closed by the piston valve due to the expanding oil pressure in the piston's upper chamber.
Meanwhile, oil pressure will also press the membrane/valve that closes the small orifice hole. When this orifice hole opens, the shock absorber oil will flow back into the chamber below the piston.
Because this orifice hole has a small hole diameter, the shock absorber oil will flow small and slowly to the piston's lower chamber. It's time when the shock absorber is damping the oscillatory forces that occur in the suspension springs.