Structures and types of shock absorbers

Structures and types of shock absorbers

Today's automotive suspension systems incorporate cylinder-type shock absorbers, most of which are of the double-acting type that generate damping forces in both the extending and contracting strokes.
These shock absorbers can be either the twin tube type or mono tube type, depending on the type of car and the car's suspension.

twin tube type

The twin tube type features a dual tube configuration. The piston valve generates damping forces in the extending stroke, while the base valve generates damping forces in the contracting stroke.
This type offers a wide adjustment range for length and readily withstands minor chips from flying rock particles. For this reason, it's widely used in automotive suspensions.

mono tube type

The mono tube type has an inline arrangement featuring an oil chamber and a gas chamber. The piston valve generates damping forces in both the extending and contracting strokes.
Due to these characteristics, damping forces have a linear relationship to piston movement. In addition, this type is easy to tune and offers good heat dissipation. They're often used in sport suspensions.

What are damping forces?

While the shock absorber's specific role is to limit spring motion and stabilize the car body, the damping forces mentioned here refer to the force that damps the movement of the relatively massive frame of the car as quickly as possible.
How are damping forces generated? As shown in the figure below and to the right, the piston moves inside a barrel filled with oil.
The piston features a hole that passes through its length. As the car body pitches or bounces, moving the piston, oil is forced through this hole against resistance. This resistance is the damping force.
また、車体の揺れの度合い、速さなどによりピストンが移動するスピードが変化しますが、ピストン移動速度が速いほど「減衰力」は大きくなります。
That is a characteristic of the damping force. (See the figure below to the left.)

Structures and types of shock absorbers

the same shape as the genuine shock absorbers

The main body of the shock absorber has the same shape as the genuine part to enable use with the genuine springs and other parts currently installed on your car. The genuine form type of shock absorber is ideal for customers who want to replace worn main bodies or customers who want to use a combination of a genuine form main body and a genuine form sport-type spring.
Another benefit is that maintenance procedures for the genuine form shock absorber are the same as for the genuine part.

coil over series
 

With this type of shock absorber, ride height can be adjusted using the full length of the main body.
Since the configuration uses the full capacity of the spring, the desired ride height can be obtained even when the absorber is installed in its fully extended state.
The full-length height adjust shock absorbers are widely used in suspensions that require settings for harsh conditions, like those encountered in serious motorsports.