Carlos:

1) I'm pretty sure IMO is internet-speak for "In My Opinion". "IMHO" is "In my humble opinion". And for lots of the other letter combo's, I've gotta ask my kid. Sometimes I don't want to know the answer.

2) Bassfisher's got it correct. You need to use a retract servo, first for the higher torque needed to push/pull the gear, second for the longer arm travel, and third because the retract servo doesn't consume power when holding a fully open/closed position (which would happen with a regular servo). You need to make sure your push rod travel is adjusted correctly: meaning the rods open/close the gear completely, as well as moving just a bit further so that the gear lock into place. If you have insufficient travel, the gear can collapse because the locks don't engage. One the other hand, if you put in too much travel, the lock will be engaged, but the servo arm may be trying to move further, which will drain your flight battery because the retract servo isn't at the end of its travel. (This sounds more difficult than it really is.)

As I recall, to activate the Robart mechanicals on my UltraSport, I needed about 1-1/8" of total travel, and ended up using a 3/32" piece of birch plywood for the servo arm, mounted inside a Hitec adjustable arm mount on an HS75. I'll try to provide a picture when I get home tonight.

Fred