Abstract: A crawler tractor in which the track rollers supporting the crawler tractor on endless tracks passing in contact therewith are carried by a support structure suspended resiliently from the track bogie. The track roller assembly is thereby vertically movable relative to the drive wheel and the track-tensioning wheel of the crawler tractor for increasing the efficiency and stability of the crawler tractor when utilizing auxiliary earth moving equipment by increasing the amount of endless track in contact with the supporting surface during operation of the auxiliary equipment. The resilient suspension system minimizes the track print when the auxiliary equipment is not being used in order to facilitate maneuvering during steer-by-driving operation.

Abstract: A multi-speed forward and reverse countershaft type power-shift transmission having speed clutches, forward and reverse clutches, housing compartments, a control valve attachment location and various related components arranged whereby the transmission is capable of being produced at relatively low cost and of conserving energy.