Patent ID: 8292909

Claim:
A medical device driven by a vacuum source, the device comprising: a working end having an operable element, the operable element coupled to a mechanism, such that when the mechanism is driven by the vacuum source, movement of a drive shaft actuates the operable element; where the drive shaft is located in a chamber and moveable between a drive stroke and a return stroke; a shuttle body moveable between a Forward and return positions, wherein movement between the forward and return positions alternates a fluid path between the chamber and vacuum source so that during application of a vacuum from the vacuum source movement of the shuttle body causes the drive shaft to cycle between the drive stroke and the return stroke; and a linkage coupling the drive shaft to the shuttle body such that as the drive shaft approaches the end of the drive or return stroke the linkage transfers a force to the shuttle body to assist in switching between the forward and return positions and prevents unstable flutter of the shuttle body between the forward and return positions.