摘要 |
When a fluid pressure in a fluid supply passage is higher than a first set pressure, a fluid in the fluid supply passage is supplied to a pressure chamber via a check valve, and when the pressure becomes lower than the first set pressure, the fluid is supplied from a hydraulic pump to the pressure chamber via the check valve. When the pressure becomes higher than a second set pressure, the fluid is discharged from the pressure chamber via a relief valve, and also when the pressure within the pressure chamber becomes higher than a third set pressure which is higher than the first set pressure but is lower than the second set pressure, the supply of the fluid is stopped. With this system, the pressure within the pressure chamber is maintained at a level between the first and second set pressures.
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