How Belleville Washers Work

12 Jan

Spring forces play a vital role in all sorts of building and engineering projects. Springs come in a wide range of shapes far beyond the commonly thought of coils and leaves. Belleville washers are a prime example of a humble but important form of spring with countless different applications.

Belleville Washers Defined

First invented and patented by Julien Belleville in 1867, the Belleville washer is a connector with a slightly angled, conical form. This causes it to act as spring, loading up bearings or joints with a predetermined, flexible amount of force. Belleville washers are used in a number of different applications for shock absorption.

While they cannot be used to replace traditional helical springs in all applications, Belleville washers perform extremely well in applications where there is minimal space for compression and expansion. They deliver a great amount of force in comparison to travel distance and the ability to stack multiple washers (see below) makes it easy to fine-tune the force they deliver.

Configuring Multiple Washers

Belleville washers can be combined to alter either the load or deflection that they deliver. A single washer delivers a specific load at a specific deflection. When washers are stacked in parallel — that is, nested inside each other — their load multiplies while their deflection stays the same. Stacking Belleville washers in series — with each washer facing away from its neighbors — will multiply deflection while keeping the load constant. Two washers in parallel have double the load, while two washers in series have double the deflection.

The load and deflection applied by a stack of Belleville washers can be further fine-tuned by building a series-parallel stack. This enables the load and / or deflection to be changed in the field by adding or removing individual washers.

Installing Washers Properly

If they are to function properly and apply the proper amount of force, Belleville washers must be installed correctly. The finish of the washers has to be suitable to the environment they are used in, and they have to react properly (e.g. not all) to the materials they come into contact with.

Most importantly, a Belleville washer exerts virtually all of its force around its outer rim. Installing one in a place where its rim does not make full contact with the surface it’s connecting to will dramatically reduce its effect.

Belleville washers do an excellent job of pre-loading a joint or bearing. They’re found in the toolboxes of workers in countless different industries, and they deliver spring forces in places where no other type of spring would work.

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