This paper describes the application of hyifraulically powered wheels to a logging trailer which is pulled by a 225-HP tractor. It discusses the advantages of the hydrostatic transmission as a means empowering the trailer. The hydraulic circuitry and its operation is examined. A cutaway view of the wheel is used to explain the operating features. Performance figures are displayed and component arrangement on the tractor are shown. Other applications of the same hydraulic wheel are presented.