Patent ID: 6240351
Filing Date: 2001-05-29
Classification: B62D

Abstract:
A control system for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor, the steering pump being responsive to steering control signals representing a status of an operator manipulated steering wheel, the steering motor providing an input to a differential track drive mechanism which responds to manipulation of the steering wheel and turns the vehicle and drives left and right tracks, the control system comprising:an engine speed sensor;a steering motor rotation speed and direction sensor; anda control unit receiving the steering control signals and coupled to the engine speed sensor and the steering motor speed sensor, the control unit, when the steering control signals indicate that the steering wheel is turned in a direction opposite to a direction of rotation of the steering motor, generating and saving a first ratio value representing a ratio of the motor speed to the pump speed, then, if the steering control signal is unchanged after a certain time duration, generating and saving a second ratio value representing a later ratio of the motor speed to the pump speed, and the control unit calculating a difference value representing a difference between the first and second ratio values, and the control unit generating a fault signal if the difference value has a magnitude which is less than a predetermined magnitude.