Belleville springs are a type of disc-shaped washer with an extremely high tensile strength. Originally developed in the mid-19th century by Julian Belleville, belleville springs are used in a variety of environments in which a heavy load bearing ability is required. Many high performance cars use a type of belleville spring in their shock absorbing systems, and belleville springs are also used in manufacturing equipment, as well as electronics.
Belleville springs can be made in a wide range of sizes, from very small washers to very large discs. In shape, they resemble a shallow soup bowl with the bottom cut out, and they are generally made from tempered steel and other similar metals that can stand up to immense pressures. Most manufacturers pre-stress belleville springs before delivering them to consumers, to make sure that they won't fail in practical applications.
Because of their construction, belleville springs can be subject to very heavy loads, and they will distribute the weight evenly around their circumference. As a result, they can be used to hold substantial loads and to distance parts of machinery from each other. They are highly useful in areas subject to thermal expansion or contraction, vibration, high bolt loads, and bolt creep, in which bolts may move around or wedge themselves out.
In the simplest of applications, belleville springs may be placed convex side out between a bolt and the surface they are attaching to. Sometimes, a small washer is used to help further balance the load, although the belleville spring is usually strong enough on its own. If a washer is used, it is placed under the outside diameter of the spring. When the bolt is subjected to stress, the belleville spring will help to distribute it evenly so that the bolt won't move or inadvertently release.
There are a number of other configurations for belleville springs in practical use, however. Sometimes they are installed in a parallel stack, increasing the amount of load they can accept. In other cases, the springs may be stacked in a series, either in front-to-front or back-to-back springs, to increase deflection. In a parallel series, the two systems are combined to increase load bearing ability and deflection. In all instances, belleville springs are said to have reached their maximum load capacity when they have flattened out.
Belleville springs are in use in a wide variety of commercial and consumer environments. In many instances in which the ability to withstand a heavy load in a small space is required, belleville springs are a good choice to balance that load safely and evenly.