| 摘要 |
In a pneumatically powered grinding machine provided with a flyweight operated speed governor there is incorporated an independently operating overspeed safety device which in case of malfunction of the speed governor is intended to obstruct further motive air supply to the motor of the machine. The overspeed safety device comprises an annular valve disk having two centrifugal weights which together with a suspender plate form a latch means by which the valve disk is kept in its open position at motor speeds not exceeding a predetermined level. In its open position, the valve disk is elastically bent about a diameter line as a result of the latch engagement between the centrifugal weights and the suspender plate. When the predetermined speed limit is reached, the valve disk is released from the suspender plate to occupy, while resuming its original flat shape, an air supply obstructing, closed position. The safety device is not resettable without dismantling the machine.
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