<div class="htmlview paragraph">This paper discusses the history, theory, operation, and refinements of one of the oldest limited-slip vehicle axle and tandem interaxle differentials that has remained in continuous production. The design uses a cam and wedge principle, but is a true differential in the manner of a conventional geared unit. Its unique drive principle provides frictional bias in a ratio between 2-3:1 to increase vehicle drawbar pull on split-coefficient surfaces.</div>