| 摘要 |
PROBLEM TO BE SOLVED: To protect a front motor against burning by anticipating the speed of front wheel on the opposite sides based on the steering angle and rotational speed of rear wheel, feeding the front motor with a current for decreasing the difference between the rotational speed and a predicted speed to determine the quantity of power, and interrupting the current supply when a reference level is exceeded. SOLUTION: A reach type fork lift truck F comprises a rear wheel disposed in the rear of a car body 2 and driven by a drive motor 6 through a steering 5, and front wheels 4R, 4L disposed in front of the car body 2 on the opposite sides thereof while being linked with front motors 7R, 7L. Normally, the front wheel idle and the lift truck F travels only with the rear wheel and a speed difference is generated between the front and rear wheels due to slip at the time of grade climbing or overloading. A controller 10 predicts the speed difference due to slip based on a steering signal and a speed signal from the rear wheel 3 and speed signals from the front wheels 4R, 4L and supplies the front motor with power such that the speed difference is decreased before determining the quantity of work. When the quantity of work thus determined exceeds a reference level, current supply is interrupted thus protecting the motor against burning. |
