| 摘要 |
PURPOSE:To carry out smooth speed-change traveling by correcting the fundamental setting of either of high/low speed by a high/low speed correcting means based on each condition of engine speed, a traveling oil-pressure load and traveling control and outputting the result to a speed-change changeover solenoid valve. CONSTITUTION:By operating a high/low changeover setting switch 31, a setting means 28 carries out the fundamental setting of either of high/low speed. Based on the judged results of an engine speed condition judging means 37, a traveling oil-pressure load condition judging means 30, and a traveling control condition judging means 45 each for judging the travel operating condition of a vehicle, a high/low speed correcting means 38 corrects the fundamental setting of either of the high/low speed and outputs a changeover signal to a speed-change changeover solenoid valve 23. Then, by switching over pilot pressure changeover valves 6, 6', the swash plate angle of traveling hydraulic motor is controlled via inclined-plate actuators 7, 8, 7', 8' to generate a low-rotation high torque or a high-rotation low torque by means of the traveling hydraulic motor. Thereby, smooth speed-change traveling can be carried out. |
