Abstract: A control system controls a tracked vehicle drive/steering system which has an engine driven hydraulic steering pump which drives a hydraulic steering motor. In one embodiment, the control system operates to gradually reduce the magnitude of the steering pump control signals if the vehicle is stationary, the clutch is engaged and these conditions persist for at least a certain time period, and to further or more rapidly reduce the magnitude if the vehicle seat is not occupied. In an alternate embodiment, the control system operates to limit the magnitude of the steering pump control signals as a function of the acceleration of wheel speed. In another alternate embodiment, the control system operates to quickly reduce the magnitude of the steering pump control signals if the vehicle is stationary, the clutch is engaged and the transmission is commanded to be in a non-neutral gear, between the time the ear is commanded and the vehicle motion begins.

Abstract: A drive and steer transmission having primary gears having circumferences approximately four times as large as the respective secondary gears they operatively engage, and an effective gear reduction is thereby established which is beneficial to use of a drive and steer type of transmission with a front engine riding lawn mower.

Abstract: In an operation mechanism of an HST system transmission apparatus of the type in which an HST system non-stage transmission mechanism for driving and an HST system non-stage transmission mechanism for turning are disposed, the HST system non-stage transmission mechanism is operated by a transmission lever and the HST system non-stage transmission mechanism for turning is operated by a round operation wheel, a steering mechanism can make a turning operation matching turn feeling desired by an operator in turning at both low and high speeds. Namely, in the operation of the HST system transmission apparatus wherein the HST system non-stage transmission mechanism (25) for driving is operated by a transmission lever (68) and the HST system non-stage transmission mechanism (28) for turning is operated by a round operation wheel (19), a speed ratio between right and let driving devices is changed in accordance with the operation turning angle of the round operation wheel (19).

Abstract: A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel. 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 which receives signals from an engine speed sensor, a steering motor rotation speed and direction sensor, 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.

Abstract: A control system is provided for a tracked vehicle drive/steering system which has an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering pump control signals, and an operator manipulated steering wheel generates steering command signals. A 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, turning the vehicle. The control system includes a steering wheel position sensor, a steering motor position sensor and a wheel speed sensor. The control system generates a motor displacement value as a function of the steering wheel position and the wheel speed. The control system also generates a motor target position value as a function of the motor displacement, and generates a motor desired position value as a function of the target position value.

Abstract: A steering mechanism that controls a drive and steer transmission and that causes the transmission to execute turns in the direction a steering wheel is turned when operating in either the forward or reverse direction of travel. In response to operator engagement of a drive control, an actuation linkage shifts an elongate member within a slot formed in a cam member that pivots in response to turning of a steering wheel. Shifting of the rod member between two positions on either side of the cam member pivot axis causes the drive and steer transmission to steer the vehicle in the desired direction when the vehicle is traveling in both forward and reverse.

Abstract: A supplemental charge for a hydrostatic steering system is provide by coupling the output of the transmission oil pump to the outlet of the steering charge pump and providing a check valve to prevent oil flow from the transmission oil pump to the steering charge pump unless the charge pump outlet pressure drops below the operating pressure of the transmission pump. When the steering charge pressure does drop below the transmission oil pressure, the check valve opens and oil is provided to the main steering pump by the transmission oil pump. A pressure transducer in the oil line activates a warning signal in the event the check valve is open more than a few minutes to alert the vehicle operator to a system failure.

Abstract: A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel. 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 which receives signals from an engine speed sensor, a steering motor rotation speed and direction sensor, and the steering control signals. The control unit calculates a motor speed threshold value as a function of sensed engine speed and steering control signals, and generates a fault signal as a function of a relationship between the steering motor speed signal and a motor speed threshold value.