摘要 |
PURPOSE: A tracked vehicle steering system with failure detection is provided to detect certain failures and prevent vehicle turning unless turning is actually commanded by the operator. CONSTITUTION: A tracked vehicle drive/steering system has an engine driven hydraulic steering pump(40) which drives a hydraulic steering motor(42). The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel(74). The steering motor provides an input to a differential track drive mechanism which responds to manipulation of the steering wheel and drives left and right tracks to turn the vehicle. The control system includes a control unit(70) which receives signals from an engine speed sensor(62), a steering motor rotation speed and direction sensor(80), and the steering control signals. 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, the control unit generates and saves a second ratio value representing a later ratio of the motor speed to the pump speed. The control unit then calculates a difference value representing a difference between the first and second ratio values, and generates a fault signal if the difference value has a magnitude which is less than a predetermined magnitude. Thus, the control system generates a fault signal when the sensed signals indicate that the steering pump swashplate position is not changing as it should in response to changes in steering wheel position. |