Important Point
What Is a Shock Absorber?
Shock absorbers may not be the most exciting part of a car, but along with tires and brakes, they are important elements of a vehicle’s safety. They are hidden under the wheel arches of a car, so it is not easy to regularly check for visible signs of damage and wear, unlike tires.
The role of the shock absorbers is to keep the car’s tires in permanent contact with the road, helping to provide optimal grip during cornering and braking. Shock absorbers are parts of the suspension, so if a shock occurs, the ride and comfort of the vehicle are compromised.
The shock absorber is a component of a suspension system that not only absorbs the shocks provided by road conditions but also maintains road and wheel contact throughout the ride, which in turn allows the vehicle comfort, safety, and dynamic ride control to the vehicle.
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Why We Need Shock Absorber?
Shock absorbers are designed to absorb or damp the compression and rebound of the springs and suspension. They control unwanted and extra spring speeds. A shock absorber keeps your tires in contact with the road at all times. Before going further, let’s discuss some keywords that will help us understand how shock absorbers work.
In elementary school, we learned about energy; in particular, we learned about potential and kinetic energy. We also learned about the Energy Conservation Act. The Energy Conservation Law states that energy cannot be created or destroyed; it can only change forms. Potentials energy is stored energy, and kinetic energy is energy in motion.
Now, let’s go back to the shock absorber. When you bump or sink on the road, your vehicle’s suspension and springs run, so the tire can stay in contact with the roads & absorb energy. This shock absorbed the momentum of the springs by converting the kinetic energy of the spring into thermal (heat) energy.
These thermals energies are then converted into hydraulic fluid. Shock absorbers are oil-filled cylinders. When your vehicle’s suspension moves, a piston moves up and down through an oil-filled cylinder. The upward & downward movement of the piston forces small amounts of fluid through the holes (small holes) in the piston head.
As only a small amount of fluid is ejected, this slows down the suspension speed and reduces the compression and rebound of the springs. Shock absorbers are also velocity-sensitive. This means that the faster the springs are moving, the more resistance the shock absorber provides.
As we all know, that shock absorber is a part of suspension used as a flexible linkage between the wheels and the frame of the vehicle, but why do we need it? So let’s find out. The use of a shock absorber between the wheel and the frame provides symmetry to the force transmissions from the wheel to the frame,
which in turn prevents mechanical failure of the suspension system. As we all know that road conditions are not consistently smooth in countries like India, we often encounter many bumps and pits in a single ride which is necessary for the vehicle to be equipped with a system that is capable of these collisions. And absorb the shaking of the pits. Make the ride comfortables for the driver and passengers.
Sometimes the intensity of these road shaking is so high that if it is moved directly into the frame, it can exceed the ultimate strength of the frame material, which in turn can lead to failure or deformation in the frame, which is not desirable. Therefore we need a shock absorber that can absorb these high magnitude road shaking before transmitting it into the frame.
For a stable ride or dynamic stability of a vehicle, it is necessary to maintain an effective surface contact between the tire and the road during the ride; it is provided with the appropriate stiffness of a shock absorber assembly by the spring in contact with the surface.
When a vehicle goes on a sharp turn due to the centrifugal force provided by this turning curve, the vehicle always rotates through its roll axis, which needs to be minimized, so we need a rigid shock absorber Requires who can roll and keep this vehicle stationary and under the control of the driver.
At the time of braking, due to rear-to-load transfer, the vehicle always tends to pitch, which is not desirable, so we need a rigid shock absorber that can absorb this pitching force and make the vehicle stable which Makes it in return—braking effect.
Working of Shock Absorbers:
The shock absorbers work as follows when the vehicle comes across a collision when the lower eye moves up. Therefore, the fluid passes from the lowers side of valve A to the upper side. But since the amount of space above valve A is less than the volume of rod G, fluid B exerts pressure on the valve.
This pressure of the fluid through the opening of the valve gives the damping force. Thus, when the lowers eye E moves down, the fluid passes from the upper side of valve A downward and also from the lower side of valve B to its upper side.
The shock absorber should be filled with shock absorber fluid at regular intervals as recommended by the manufacturer or when its condition is required. Modern telescopic shock absorbers are no longers serviced. If they leak or do not give proper resistance to pushing and pulling, then they should be replaced.
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Types of Shock Absorbers:
The following are different types of shock absorbers:-
#1. Hydraulic
A hydraulic type shock absorber is now used on all passenger cars. They increase the resistance to spring action by forcing a fluid through the check valve and small holes.
#2. Double-Acting Shock Absorber
Double-acting shock absorbers offer resistance during both compression and rebound of the springs.
#3. Single-Acting Shock Absorber
A single-acting shock absorber provides resistance only to rebound.
#4. Friction
Friction-type shock absorbers have become virtually obsolete due to their non-predictable damping characteristics.
#5. Lever
The lever-type shock absorber is of the indirect-acting type. It is carried through a lever and links to the chassis. As the axle moves up and down, the arrangement of the double piston forces the oil through a valve.
#6. Telescopic
The telescopic type shock absorber is of the direct-acting type. It is placed between the axle and the frame. A simple diagram of the telescopic shock absorber is shown in the figure. Its uppers eye is attached to the axle, & the lower eye is attached to the chassis frame.
A two-way valve A is connected to a rod G. The second two-way valve B is connected to the lower end of cylinders C. The fluid is in the space above A and valve D 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 closed by rod G is brought down into the annular space via the bending path.
Testing of Shock Absorbers:
Shock absorbers should be checked by driving the front or rear of the vehicle up and down rapidly. If the vehicle does not rest almost immediately, the shock absorber must be removed for further testing. Often the noise shock occurs with an armor-to-frame connection. These joints should always be tight.
In the case of damage to the shock absorber, the operation may be erratic and may result in dampness and vibration, affecting the result. Noise may originate from other sources. Therefore, before replacing the shock absorber, carefully inspect the entire suspension system, and the shock absorber mounts on the body and axle.
Check that the shock absorber mounting eyes are firmly closed to the rubber bushes and are not worn. Replace the damaged or damaged parts. Other possible causes of noise are due to deformation of pipes or obstacles against stones thrown by wheels.
Vibration in the damping effect can be in the form of either an increase or a decrease in the damping capacity. Generally, the first case is rare and corresponds either to the condensation of fluid or to closing valves and settings, resulting in an increase in shock absorbers’ resistances. The second case may be the result of some internal part breakdown, fluid loss, or stuck valves.
Frequently Asked Questions (FAQ)
What Is a Shock Absorber?
A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Most shock absorbers are a form of dashpot, a damper that resists motion via viscous friction.
Working of Shock Absorbers
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.
Shock Absorber Working Principle
All hydraulic shock absorbers work by the principle of converting kinetic energy (movement) into thermic energy (heat). For that purpose, fluid in the shock absorber is forced to flow through restricted outlets and valve systems, thus generating hydraulic resistance.
Types of Shock Absorbers
- Hydraulic
- Double-Acting Shock Absorber
- Single-Acting Shock Absorber
- Friction
- Lever
- Telescopic
Shock Absorber Test
The usual way to test a shock absorber is to push down on a corner of the vehicle a few times to get it to bounce and then stop pushing and see how much it continues to bounce before stopping. A good shock absorber should stop the bouncing right away.
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