Patent ID: 6416440
Filing Date: 2002-07-09
Classification: B60W,F16H,Y10T

Abstract:
A semi-automatic power shift transmission for use in an industrial vehicle, comprising:a shift lever with at least first and second gear positions; a hydraulically shifted transmission gear mechanism operable in one of at least first and second gear ratios corresponding to the first and second gear positions; electromagnetic actuator means for, when energized, causing the transmission gear mechanism to be either up-shifted from the first to the second gear ratio or down-shifted from the second to the first gear ratio; a transmission speed sensor for detecting the output speed of the transmission gear mechanism to generate a transmission speed signal; an engine speed sensor for picking up the speed of a vehicle engine to produce an engine speed signal; a steering wheel angle sensor for measuring the steering wheel angle to issue a wheel angle signal; and a transmission control unit responsive to the transmission speed signal, the engine speed signal and the wheel angle signal for energizing the electromagnetic actuator means to thereby carry out the up-shifting and the down-shifting operation, wherein the transmission control unit is adapted to perform the up-shifting operation in the event that a load ratio calculated by dividing the transmission speed with the engine speed is greater than a preselected reference load ratio, with the transmission speed larger than a preselected reference up-shift speed and the steering wheel angle smaller than a preselected reference angle.