Project Description

Pinion Washer


Fortune 500 commercial transportation transmission manufacturer


The customer was experiencing high failure rates in its DU coated pinion thrust washers that were used within a planetary gear set. The premature failures of the metal DU washer led to excessive warranty expenses.

The customer was interested to learn whether a high-performance plastic washer would have a longer life expectancy under the required high velocity, resulting in high levels of centrifugal force the part encountered. Allegheny Performance Plastics was asked to convert a DU metal washer to a high-performance plastic washer that would fit within the existing design space as a drop-in replacement. The customer needed a quick solution to replace the existing units under warranty and to supply units for current and future production.


This DU washer, which was stamped and then finished with a wear coating, is part of a planetary gear set connected directly to an electric motor. The weight of the metal led it to generate a lot of centrifugal force when rotated at high speeds. This centrifugal force caused the inside diameter of the washer to wear away and take an oblong shape.

The Allegheny Performance Plastics engineering team quickly obtained the relevant performance metrics — load and velocity and environmental conditions — from the customer to research the appropriate high-performance plastic for this application. In-house developed tribological test data was readily available and used to support the prototype design and material selection.


Within 3 weeks from the initial meeting with the customer, Allegheny Performance Plastics designed, machined and delivered prototype parts. Within 12 weeks Allegheny Performance Plastics was delivering PPAP-approved production parts at production rates. 

Furthermore, because the high-performance plastic washer has significantly less mass than the bronze washer, the centrifugal force generated is significantly lower, which reduces the wear rate on the washer. 

The result was a very successful product development that is still in production today — without a single part failure.