To keep bolted connections tight, we can choose from several methods. The most common is the insertion of a locking device between the rotating part (nut) and the parts being fastened (i.e., bus bars). That locking device often is a split-ring lockwasher. Such a device does not meet all locking device requirements, however. Enter, the Belleville washer.

The Belleville is a disk spring that applies pressure to the connection once you clamp down on it with the proper amount of force. The advantage of this washer is that it applies clamping pressure along a continuous arc pattern, instead of concentrating it at one point the way a split-ring lockwasher does. While you should use a split-ring washer only at the nut end of the connection (normally), you can use Belleville washers in tandem. One at the nut end and one at the bolt head end. This is a common way to use these washers, especially when assembling bus bar.