Wire cutting valve actuator

A valve actuator for opening and closing a valve, comprising:

• a housing;
• a shaft movably mounted to said housing for translation between a first and second position, the valve being open in said first position of said shaft and closed when said shaft is in said second position;
• means for selectively urging said shaft between said first and second positions;
• force amplifying means adapted for selective engagement with said shaft before it reaches its second position, said force amplifying means storing a force and so disposed as to selectively apply substantially all of said stored force in a direction parallel to said shaft upon engagement with said shaft;
• collet means in said housing mounted adjacent said shaft and adapted to move selectively in tandem with said shaft for storing and releasing of a force by said force amplifying means;
• said shaft is formed having a means for selectively retaining said collet means, said retaining means on said shaft selectively cooperating with said housing to retain said collet means for tandem movement with said shaft in both directions for a portion of the range of movement of said shaft about its second position;
• said housing is formed having a first tapered surface and said collet means is formed having a second tapered surface cooperating with said first tapered surface;
• said collet means being in continual contact with said force amplifying means;
• whereupon during a portion of the time as said shaft is moved from its second to its first position said housing retains said collet means to said retention means for tandem movement of said shaft and collet means to compress said force amplifying means, and when said shaft movement reverses as a result of the action of said urging means, said force amplifying means is released as a result of camming said second tapered surface of said collet means against said first tapered surface of said housing, resulting in movement of said collet means toward said retaining means on said shaft, with the force retained in said force amplifying means applied to said shaft through said collet means.