Shocks vs. Struts: Know the Difference

Bindu swetha May 10, 2019
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One usually enjoys a smooth ride on the road, due to the combination of shock absorbers or struts and springs. The springs in car assembly help support the vehicle weight and prevent jolting due to irregularities on road, ensuring a smooth ride. Though struts and shocks, limit the vertical motion of spring, both have structural differences.
Though most people think that shocks and struts are the same elements and are interchangeable, they are actually not! Although both are used to limit the motion of springs, the difference lies in the structure of the suspension.

Shock Absorbers

In simple terms, shock absorbers are nothing but oil pumps. Structurally, the shock absorbers are made of a piston, coil, and the hydraulic fluid.

The piston, attached to a piston rod, works against the hydraulic fluid in the pressure tube. Whenever there is a jolt or bump, the pressure is exerted on the fluid.
The fluid then flows out of the tiny holes inside the piston. This flow slows down the motion of the piston, thus slowing down the spring movement, and preventing the impact of the jolt.
This assembly ensures that the tyres of the vehicle are in contact with the ground, at all times.

All the kinetic energy that is accumulated in the shock is thrown out or dissipated in the form of heat.

Struts

The struts are a part of the suspension system of the vehicle and support the vehicle weight. Struts contain a combination of coil spring and a shock absorber. The struts connect the bearing to the lower ball joint so that the vehicle can turn in any direction, due to the pivot of this assembly.
Struts help in maintaining the desired orientation of the vehicle and also support the vehicle weight.

When the vehicle is in motion, the internal shock absorbers dampen the movement of the spring, while the shocks absorb the impact on the vehicle, and the struts control the motion of the vehicle.

The Differences

The major difference between the both lies in their replaceability. While shocks can be easily replaced and are less expensive; the struts are complicated to replace and are more expensive.

Due to the strut's position, the vehicle needs wheel-alignment, after strut is replaced. Strut is a structural part of the vehicle's suspension system but a shock is not.
Strut receives multidirectional loads while shocks receive impact on its axis.

Struts are attached to the lower bearing and at the top side, in the swivel device. The shock absorbers are attached to the vehicle in silent blocks without any swivel device. The piston rod of the strut is much larger in diameter than that of the piston rod of a shock absorber.
The shock absorber can work as a part of the strut assembly, but functionality vice versa isn't possible.

If the strut malfunctions, the entire car can fail, due to strut's versatile load bearing capacity and reinforced elements.
However, if the shocks malfunction, the vehicle will continue to move, but the driver will feel the jerks and jolts caused due to the bumps and potholes on the road.

So, if a shock fails, the vehicle loses its stability; however, if the strut fails, the vehicle cannot be driven at all!