Thrust Washer Defined

A thrust washer is a circular shaped component of a mechanical structure that is used as a bearing surface for rotary applications. They are sometimes called rotary thrust washers, and are designed to prevent movement along the axis of a shaft. Materials are usually steel, bronze, plastic, or others with low friction coefficients.

Precision-engineered thrust washers are used in high-wear applications such as automobile engines, transmissions, power take-off's, pumps, axle assemblies, motors, and winches. They can be made from case-hardened steel, through-hardened steel, stainless steel, bronze, phosphorous bronze, and brass. Graphite is sometimes used in high-temperature applications. Plastics are used for low speeds and light loads. Rubber and lignum vitae are used in water-lubricated bearings.

Thrust washers can be made in standard thicknesses, with various inside and outside diameters as needed. Important considerations include flatness and parallelism requirements, surface finish, heat treatment, through-hardness, passivating, and plating.