| 摘要 |
PURPOSE:To prevent a creep start due to pump idling by changing over a pipe line from a pilot pump on stepping down an accelerator pedal and operating a pipe line changeover valve on a main pump via changeover valve for moving forward and backward. CONSTITUTION:In a hydraulically driven vehicle such as a wheel type hydraulic power shovel, a prime mover 1 is operated to drive a pilot pump 4 and a main pump 8 and generated hydraulic pressure is introduced to a running motor 9, thereby effectuating the travel of a vehicle. A pipe line from the pilot pump 4 is connected to an electromagnetic changeover valve 21 operating for changeover on the foot switch 23 of an accelerator pedal 2. After a pilot valve 5 for changeover between forward and backward running has been set, the accelerator pedal 2 is stepped down. Then, the hydraulic pressure of the pilot pump 4 is introduced to the predetermined port 6a or 6b of a control valve 6 and the hydraulic pressure of a main pump 8 is led to the running motor 9, thereby starting the travel of the vehicle. According to the aforesaid constitution, a creep start due to pump idling can be prevented.
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