Belleville washer

A Belleville washer is a spring shaped like a washer, and it is also called a coned-disc spring, conical spring washer, disc spring, Belleville spring or cupped spring washer. Its spring action comes from its shape, a cone frustum. The name honours Julien Belleville, who patented a disc spring design at Dunkirk, France, in 1867 that already held the principle of the disc spring, although the real inventor of the washer is unknown. Over the years many profiles have been developed, and the most widely used today are the profiles with or without contact flats, while others such as disc springs with a trapezoidal cross-section have lost importance.