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:
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.
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
hydraulic power is lost, or the control handles are placed
in the neutral position.
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.
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.
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 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.