Patent ID: 6343250
Filing Date: 2002-01-29
Classification: F16H

Abstract:
A method of controlling a transmission having (i) a variable displacement hydraulic pump, (ii) a hydraulic motor operatively connected to the pump, (iii) a speed sensor operable to sense a speed of an output shaft of the hydraulic motor, (iv) a first actuator for setting displacement of the pump in a positive displacement range in response to a first actuator command, (v) a second actuator for setting displacement of the pump in a negative displacement range in response to a second actuator command, and (vi) a controller operable to transmit first actuator commands to the first actuator and transmit second actuator commands to the second actuator in response to operator inputs, comprising the steps of:receiving operator inputs which require the displacement of the pump to move from the positive displacement range to the negative displacement range; generating first actuator commands which cause the first actuator to set the displacement to zero; and generating second actuator commands in response to the motor speed reaching a predetermined motor speed limit which cause the second actuator to set the displacement of the pump in the negative displacement region, the second actuator commands coinciding with a transitioning drive condition of the transmission between first and second transmission operating ranges.