'Preloading' has an impact on the working of compression springs - correctly setting the preload can improve the functionality of your springs. This article focuses on the principle of preloading, its role in compression springs, and its benefits. We will discuss practical examples like how adjusting preload affects the lifespan of tactical equipment. The information is designed to aid your understanding and provide practical skills for engineering tasks. However, preloading is not always the best option - it is more effective under certain conditions. Therefore, knowing when to employ it can affect your design choices significantly.

What is Preloading?

Preloading refers to the load applied to a compression spring prior to its operation, ensuring that the spring works within a given range of deflection. Using an appropriate preload enables the spring to navigate the necessary operational forces.

An automotive shock absorber often employs an example of a preloaded spring. With no additional load, the spring accounts for road imperfections. When the vehicle carries passengers or cargo, the preloaded spring modifies its behavior to accommodate the increased shock and vibration.

The main reason preload is important is to initially set the spring. Setting the spring is basically just a first compression that changes its natural free length and puts it into a more repeatable state. Failing to set the spring before operation could lead to it permanently deforming (setting) unexpectedly after it is mounted. Oftentimes the manufacturer will pre-set the springs before shipping them to you, however it can't hurt to check to ensure this process was done. Most manufacturers will also supply their specifications as "post-set", meaning their initial coil off the manufacturing machine is going to be a bit longer than the post-set version delivered to you.

Determining the right preload value entails gaining insight into the load requirements of the application and the physical characteristics of the spring. Factors such as coil size, material used, wire diameter, and elasticity need to be taken into account. By considering these elements, it becomes possible to enhance system performance and increase the longevity of the spring.

How to Preload a Compression Spring

To preload a compression spring, the anticipated load the spring expects to bear should be determined through a required calculation process. The importance of this calculation is illustrated, for instance, in a scenario where an engineer determines a spring must withstand a 50kg load. The engineer compresses the spring until it achieves the capability to operate under this load.

After the correct preload level has been established, the operational setting of the spring, such as its placement within a device or mechanism, is then arranged. This assembly's design should enable it to exert the necessary pressure to maintain the set spring preload. A common scenario is a commercial vehicle's suspension system where the spring needs to be preloaded to adapt to changing load conditions - from accommodating maximum cargo to only supporting the vehicle's weight. Maintaining the spring's preload is done to allow the spring to react appropriately to varying load situations.

It should be highlighted that although keeping a spring preload is typically advantageous, changes may be necessary depending on operational requirements or conditions. Ongoing assessments of the spring's condition, and its performance in its working environment are critical as factors like wear and tear or changes in operating parameters may necessitate adjustments to the preload. Keeping accurate observations and making necessary alterations to the preload help maintain the spring's performance.

Benefits of Preloading


Within engineering, the appropriate use of compression spring preloading is crucial. Preloading serves multiple functions such as improving stability, shortening settling time, and advancing control of force. These all contribute to a spring's increased lifespan. Through successful application of preloading, engineers can adjust their spring design to fulfill desired operational needs. It's accurate to suggest that utilizing preloading can optimize a compression spring's performance within any given use-case scenario.