| 摘要 |
<P>PROBLEM TO BE SOLVED: To convert a negative brake to a brake-on state promptly and securely even if there occurs such a situation that a brake selector valve is not switched from a brake-off position to a brake-on position due to a failure or the like of a control means. Ž<P>SOLUTION: The brake device is constituted by providing the brake selector valve 19 to a brake line 18 connecting a hydraulic pump 11 and a tank T and the brake cylinder 16 of the negative brake 15, and the brake selector valve switches the brake-off position (i) and the brake-on position (ii). A pressure relief circuit 24 which brings about a brake-on state by releasing the hydraulic pressure of the negative brake 15 to the tank T is connected to the brake line 18. A throttle 25 and a flow regulating valve 26 are provided at the pressure relief circuit 24, and the opening of the flow regulating valve varies in accordance with a pressure difference between the front and the rear of the throttle 25. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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