ORIGINAL: j.duncker
But going back to the OPs problem if he gets a high torque proportional servo and a servo slower then he can achieve his desired goal.
A Futaba S3010 handled a set of 40/60 size retracts just fine for me.
That might work
IF you can set the end points exactly but if you don't it can leave the servo in a stalled condition which will draw excessive current. Even with the end points set correctly the servo could draw extra current trying to keep the gear in position.
NOT a good idea in the long run.