In the field of shock absorbers, choosing the appropriate components can be a detailed task for engineers. One crucial component is the compression spring. The correct size can improve the safety of the machine, an aspect often considered in vehicle suspension systems. This article looks at the main parts of shock absorbers, the forces created by the compression spring, and those from the damper. Moreover, we'll explore several overlooked factors that might affect the performance. Presenting all this information simply and clearly, our goal is to assist you in tackling this common engineering challenge.

Shock Absorber Main Components

A shock absorber comprises two primary components: the compression spring and the damper. The compression spring is designed to take in and store mechanical energy. It copes with shocks or vibrations by means of compression and expansion. The selection of the spring's material and the diameter of the wire is a crucial part of the design process. High-strength alloy steels are typically utilized for projects that involve high-stress, while stainless steel is preferred for its ability to resist corrosion. The diameter and the numbers of coils in the spring are important as well; these attributes dictate the load-bearing ability and deflection rate of the spring. However, increasing the number of coils could lead to a decrease in the spring's stiffness. Precise calculations and minor modifications are required at this stage of the design process.

The damper, the second major component of the shock absorber, serves to lessen, and eventually eradicate, the oscillations caused by a shock or impact. The damper operates in a manner similar to a hydraulic pump, absorbing the energy displaced by the spring and changing it into heat energy. This transformation of energy slows down the movement of the spring, thus returning the system to a balanced state. It should be noted, though, that an overly effective damper can hamper the spring's shock absorption ability. This indicates that the damper and spring should be harmoniously balanced to ensure optimum performance of the shock absorber.

Forces from a Spring

Designing a compression spring for a shock absorber necessitates an understanding of the forces at play: the spring force and the damping force.

The spring force is the energy that the spring releases when it either contracts or stretches. There is a direct relationship between this force and the displacement of the spring: increased displacement results in an increased spring force. The spring force also varies with the spring constant, which is dependent on the properties of the spring, such as the material, wire diameter, coil diameter, and coil count. A practical illustration of this is in creating a suspension system for a motorbike. A rider with a greater weight will create more displacement of the spring under a load, necessitating a more robust spring. By adjusting these variables, a balance can be attained providing a smooth ride and managing heavier loads without causing harm to the spring.

Forces from a Damper

In shock absorber design, the damper generates forces. These forces decelerate or halt oscillations induced by the compression spring. The damping force is either produced by fluid movement inside a hydraulic damper's piston or from the deformation of elastomers in various damper designs.

The damping force directly correlates with the damper's motion speed and inversely with its direction. Therefore, a high-speed damper application requires a spring to endure a larger damping force. Conversely, a slower damper operation needs a spring with lower strength requirements. This rule applies only to velocity-dependent dampers.

Understanding damper forces aids in appropriate spring selection. Springs need to be selected according to the specific conditions of use affecting safety. For example, an automobile's suspension system employs a coordinated spring and damper set to maintain consistent ride quality, which aids in reducing accidents caused by irregular vehicle behavior.


Sizing a compression spring correctly for a shock absorber is a practical skill. It requires understanding the basic dynamics of force and the main elements of the spring and damper. This knowledge enables an engineer to evaluate the forces produced by both parts. Thus, to design a reliable shock absorber, the engineer must focus on the selection and design of the compression spring. The effort put into this area will enhance the overall performance and lifespan of the shock absorber.