The Booster drive system is designed to enhance the gradient-climbing and traction capability of a trailer-type coal hauler by driving the trailer axle hydrostatically from a power pack mounted on the prime mover. Drive from the booster system is available at low to medium speed, where additional power is usually required for ramps or in soft ground conditions, and is disabled when the prime mover is in higher than fifth gear. The drive is coupled to the wheels through one-way clutches, and free wheels when operating in the higher gears.
Booster drives can be fitted to new Coal Haulers or retro-fitted to existing haulers. To date booster drives have been fitted to 160 tonne capacity haulers but the system can be modified for larger capacity haulers if required.
The hydraulic system is a closed-loop type using a variable displacement axial-piston hydraulic pump driving a pair of radial-piston hydraulic motors located within the rear axle. The motor torque is transmitted to the wheels through planetary reducers.