| 摘要 |
The invention comprises a trigger mechanism providing stepwise linear motion responsive to a shaft rotating above a predetermined rate. The trigger mechanism comprises a rotating shaft having a collar thereabout attached to rotate therewith. Also part of the mechanism are a plurality of arcuate cams mounted within the collar to rotate therewith, each biased with the ends of the arcs thereof adjacent the collar at a normal shaft rotation rate of no more than said predetermined rate and the midpoints of the arcs thereof spaced away from the collar towards the shaft. The midpoints of the arcs are forced centrifugally to adjacent the collar when the shaft rotates above said predetermined rate (at overspeed). Each cam has a channel therein and fits against a respective adjacent cam end to end to form a generally circular arrangement thereof, said circular arrangement defining a first circular path therein at a normal shaft rotation rate up to said predetermined rate a first radial distance from said shaft and a second circular path therein at a second radial distance above said predetermined shaft rotation rate. The mechanism further includes non-rotating cam-follower means having a tang extending therefrom into said first circular path at said normal shaft rotation rate and into said second circular path above said predetermined shaft rotation rate, said cam-follower means constrained to shift laterally responsive to said tang shifting from a respective one to a respective other of said first and second circular paths and providing a pair of detent positions separated by a distance generally equal to said lateral shift a first of which is further from said shaft and a second of which is closer to said shaft. Also part of the trigger mechanism is a rod having a first end extending outwardly from said cam-follower means away from said shaft and a second end biased against a respective one of said first and second detent positions indexing said tang in said first circular path at said normal shaft rotation rate and in said second circular path at said predetermined shaft rotation rate.
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