1.12.4. Track Drive System

TM 5-3895-373-20 1.12.4. Track Drive System. The track drive system propels the paving machine. The track drive system is a parallel system driving both left and right tracks. Main components of the track drive system are as follows: a. Hydraulic Propulsion Motor. The hydraulic propulsion motor is a two speed fixed displacement motor. High or low speed selection is made by a moveable internal port plate. The high or low speed port plate position is controlled by a solenoid valve activated by the travel switch on the operator gauge panel. The motor shaft mates with the speed reduction gearbox. Hydraulic power to drive the motors is provided by the hydraulic propulsion pumps. b. Speed Reduction Gearbox and Brake. The speed reduction gearbox is mounted to the drive hub assembly from inside the paving machine frame. The gearbox converts a high speed, low torque input to a low speed, high torque output. An integral spring applied hydrostatically released brake engages whenever hydraulic power is lost, or the control handles are placed in the neutral position. c. Drive Sprocket Gear. The drive sprocket gear is directly attached to the drive hub axle internal to the drive hub assembly and connected to the speed reduction gearbox. The axle spins on two sets of conical bearings. The drive sprocket gear is bolted to the outboard face of the drive hub assembly. d. Track Idler Roller and Tensioning Cylinder. The track idler roller slides forward and backward in the track frame. During operation, the track tensioning cylinder keeps a constant load on the idler roller, removing slack from the track chain. e. Track Rollers. Track rollers support the track chain. Two track rollers are mounted to the top of the track frame, and eight are mounted to the bottom of the track frame. f. Track Chain. The track chain consists of interconnected links where each link has a track guide and hardened rubber track pad. This provides a large surface contact area with the ground. The track chain provides the travelling surface for the paving machine and creates traction to allow movement. 1-9