[Kevin Sevcik]

So to answer the actual question posed, 57 had a mechanism like this last year. You'll find that the vast majority of devices out there simply won't release under load. If you're winding back and then using the latches to control the final release then it's not as much a problem and you could use an andymark shifter and an andymark planetary adapt an FP to the tranny. That would work fine as long as you back the motor up so the springs take the load before you try disengaging.

That said, our solution was a little different. We used a worm-worm gear combo to drive the retracting pulley. An FP through a BB tranny drove the worm, and that whole assembly was mounted on a pivot and gravity biased to the worm wanted to pull away from the gear. So to retract, we'd use a cam on a servo to push the worm into the gear and retract. To fire, we'd move the cam the other way and then we'd have to reverse the motor slightly. The worm was arranged such that while retracting, it was actually pushed into the gear thanks to the location of the pivot point. Reversing the motor broke changed thing s enough that the worm broke free of the gear and out went the spring.