| 摘要 |
PURPOSE:To facilitate clutch operation, by weakening the energizing force of a second valve body through stepping of a clutch pedal and increasing of hydraulic force, thereby lowering pneumatic pressure for an air clutch and achieving a proper air pressure characteristic. CONSTITUTION:Stepping operation of a clutch pedal 57 produces hydraulic force from a hydraulic chamber 59 for sliding second and third springs 87, 88 sequentially through a piston 72, thereby energizing force of first subrod 82 is weakened to weaken the energizing force for a second valve 63, and the pneumatic pressure for an air clutch is lowered gradually to provide an air pressure characteristic suitable for the air clutch. Consequently, abrupt connection/disconnection of clutch through slight stroke of the clutch pedal 59 which often occurs in an air clutch employing a conventional pressure control valve can be prevented, thereby clutch operation can be facilitated. Furthermore, heavier stepping force is required as the stepping amount of the clutch pedal 57 increases, thereby natural feeling of clutch operation can be provided to the driver.
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