| 摘要 |
<p>The switch unit, suitable for use in instances of emergency and also for a normal electrical shut-off and re-setting of a controlled system, features a snap-action electrical switch, as an example, a microswitch type control operated selectively (or jointly) by a pair of like end-anchored tension cables which have their inner ends connected to the unit's operating and re-set signal arm to trip the latter from a normal release position upon a tensioning of either cable by an attendant. The tripping of the arm causes it to operate the snap-action switch, and the arm is automatically locked in the tripped position thereof, having with said switch typically interrupted the electrical operation of the controlled system. That is, a tensioning of either one of the cables under a force exceeding a very moderate value occasions a limited rotation of a shaft carrying the arm; this suffices to actuate the snap-action switch, and thereby through conventional wiring means to initiate an instantaneous cut-off of the system's electrical supply. The shaft and arm are automatically locked in their tripped condition by a locking plate fixed on and rotatable with the shaft, which plate presents locking pins adapted to engage and latch in a fixed keeper plate of the switch unit. The locking plate is axially movable with the shaft in opposition to relatively mild spring bias to disengage the locking pins from the keeper plate, thereby releasing the shaft for manual counterrotation from locked condition to normal release condition.</p> |
