| 摘要 |
<p>PURPOSE:To prevent an oil hydraulic pump from deteriorating its function by constituting the pump such that a selecting member additionally detaches a selector valve from a stopper to switch a compressed air chamber to air exhaust and adapts the valve by separation to switch the chamber to an air feed by cam action of an engaging device and an engaging groove. CONSTITUTION:Compressed air is always fed to a compressed air chamber 14. When a plunger 9 reaches a stroke final end, a selector valve 24 advances closing a main passage 15, and the air is fed to the chamber 14 from a subpassage 16 of fine bore. When the selector valve 24 is detached from a stopper 27, an inner hole 25 is opened exhausting the compressed air in the chamber 14 to an exhaust chamber 19. While when the plunger 9 is returned to a stroke start and, the selector valve 24, reset retracing, closes the inner hole 25, and the air is fed to the chamber 14 by opening the main passage. Since the air is always fed to the chamber 14 through the subpassage 16, the plunger 9 advances, even at a very fine speed, pressurizing the air before the selector valve 24 is surely detached from the stopper 27 in the stroke final end.</p> |
