Image Number 4 for United States Patent #5775453.
A traction control system used to control a hydraulically propelled vehicle having front and rear drive assemblies has a variable displacement hydraulic motor coupled to each drive assembly. The hydraulic motors are connected in parallel to a pump. A control system senses the speed and direction of each motor as well as the grade of the ground surface. The controller uses this data to control the front and rear hydraulic motors. If the controller determines that one of the drive axles is slipping, it will destroke that axle's motor. However, if the vehicle is traveling downhill, the downhill drive assembly will not be destroked.