Abstract: The invention relates to a variable speed fan drive. There is a need for a variable speed fan drive with fewer seals and bearings, which is operated by system hydraulic pressure, which has fewer parts and which is simpler to assemble. A variable speed fan drive is provided for a vehicle powered by an internal combustion engine. The fan drive has a driver variable sheave unit, a driven variable sheave unit and a belt engaging both the driver and driven variable sheave units. The driver variable sheave unit includes a driver shaft drivingly coupled to an engine output shaft, a first axially fixed half sheave mounted for rotation with the driver shaft, and a first axially movable half sheave member mounted for rotation with the driver shaft and movable axially on the driver shaft. The first axially movable half sheave member includes a belt engaging flange formed integrally with an axially movable piston member mounted for rotation with the driver shaft and movable axially in response to hydraulic pressure.

Abstract: A cutter bar is provided for trimming debris away from the wheel-track interface of a tracked vehicle. A pivot attachment is provided wherein a knife having a cutting edge is removably mounted to a bracket by way of fasteners which will shear when a pre-selected force is applied to them. The bracket is mounted to the vehicle structure so that the knife is disposed in close proximity to the drive wheel and endless track of the vehicle. Accordingly, when a piece of tough debris is encountered by the knife edge some of the fasteners will shear and the knife pivots out of the way so that the debris can pass by without causing damage to the wheel or track. The knife and fasteners being readily serviceable with inexpensive parts.

Abstract: The adjustment mechanism of the present invention is mounted to a frame and comprises an alignment cam that is pivotally mounted to the frame by a tension link pivot pin. The alignment cam is provided with an actuating arm that is coupled to a longitudinally extendible adjusting member. The longitudinally extendible adjusting member comprising a screw jack. A tension link is pivotally mounted to the tension link pivot pin. Camming surfaces on the alignment cam are skewed with respect to the transverse axis defined by the tension link pivot pin so that rotation of the alignment cam twists the tension link and thereby the idler wheel predominately about a vertical axis. Albeit to a lesser degree, rotation of the alignment cam also twists the tension link and idler about a longitudinally extending horizontal axis. Therefore by extending or retracting the screw jack, the toe-in/toe-out orientation of the idler wheel can be adjusted.