| 摘要 |
<p>1,133,438. Stop-gear for pneumatically driven tools. CHICAGO PNEUMATIC TOOL CO. Dec. 30, 1966 [Jan. 11, 1966], No. 58359/66. Heading F1K. A rotary tool includes valve means 22 controlling flow of operating air to the motor 11, manually operable means 57 for normally selectively opening and closing the valve means and overspeed control means responsive to overspeeding of the motor for automatically closing the valve means independently of the manually operable means and simultaneously disabling the manually operable means from being operated to reopen the valve means. The tool may include a slide valve 22 controlling flow of operating air from an inlet chamber 18 to the motor, the valve having a rear head end exposed to pressure of air in the inlet chamber and having an opposite forward end exposed to pressure of air in a pressure chamber normally counterbalancing that in the inlet chamber heavy sprung means 34 normally holding the valve closed, a plunger 36 normally selectively cammable to move the heavy spring means away from the valve and carrying a light spring 38 movable with the plunger against the valve to open the valve, the valve in open condition being responsive to the pressure of air in the inlet chamber to move to closed condition relative to the light spring when relieved of the counterbalancing pressure of air at its forward end, frangible air release means 73 normally blocking relief of air from the pressure air chamber and centrifugally operable flyweight means 62 carried by the spindle responsive to overspeeding of the motor to engage and break the air release means so as to release air from the pressure chamber and as a consequence relieve the counterbalancing pressure of air from the forward end of the valve. As shown the flyweight is disposed in a diametrical bore of the spindle above the grinding wheel 13. A speed control governor may be arranged between the slide valve and the motor to maintain the speed of the motor within a predetermined range.</p> |
