ELECTRONIC POSITION CONTROL SYSTEM
An electronic control system for selectively positioning a controlled member (16) at one of a plurality of predetermined positions, the system including a reciprocating member (20) for driving said controlled member (16), a reciprocating drive member (22) for driving the reciprocating member (20) in one direction and being movable relative to said reciprocating member (20) in the other direction, said reciprocating member (20) being biased in said other direction, the reciprocating member (20) having a series of formations (26) spaced along the direction of reciprocation to correspond to said plurality of predetermined positions, an electronically controlled detent (25) mounted at a fixed position along the path of reciprocation, the detent (25) being movable between first and second positions, the detent (25) in said first position being arranged to engage a selected one of said formations (26) to arrest movement of the reciprocating member (20) in said other direction, and in said second position being arranged to reside at a remote position whereby it does not engage any of said formations, electronically operable means for controlling movement of the detent (25) to said first position such that engagement with one of said formations can be selected.