| 摘要 |
PURPOSE:To improve the safety by providing a brake circuit with a brake control valve adapted to operate on sensing pressure in a short circuit formed between a switch valve and a hydraulic motor. CONSTITUTION:A brake circuit between an operation valve 18 and a brake cylinder C is provided with brake control valve 32 adapted to operate on sensing pressure in a short circuit formed between a switch valve 15 and a hydraulic motor (m). In this arrangement, when the switch valve 15 is restored to its neutral position, a hydraulic brake is operated to stop the hydraulic motor (m). When pressure in main passages 19, 20 is decreased, the brake control valve 32 is switched to connect a pressure chamber 30 of the cylinder C to a tank, whereby a parking brake is forced to function. When a hydraulic brake gets out of order, as pressure is not generated in the main passages 19, 20, the parking brake is forced to function. Accordingly, the safely can be improved. |
