Analysis of a hydrostatic transmission driveline for its use in off-road multiple axle vehicles

There is a vast range of off-road multi-axle wheeled vehicle configurations. Some of the most common are the three axle rigid vehicles or the four axle articulated vehicles. However, these types of vehicles have the problem of using very complex transmission configurations. In addition, the requirements in terms of torque in each of the wheels are quite variable and non uniform. This work aims to model and study, from the standpoint of performance and energy efficiency, the driveline of such vehicles. The modelling process for the design and analysis of a hydrostatic transmission aimed at off-road multiple axle vehicles has been conceptually described. Mathematical models for the main components of the transmission and a global model of the driveline have been defined. A specific example study is presented, applying the described procedure. Results show that the overall performance of the transmission is highly dependent on the operating conditions, on the selected configuration and on the used components. The results also show that the actual instantaneous efficiency of each of the components is usually far below their maximum catalogue value. In the case study efficiencies up to 64% have been reached for the overall transmission.