They are for our minibot deployment. We retract a piston and set up in the back and pulls on wire rope strung to a 3:1 pulley reduction. The piston pulls and then transfers that motion to the polycarb tray to shoot out our minibot.
That by the way is in the less than 2 second club.
The pivot is fixed. It has great structural integrity that way but is a pain when trying to release the tubes. Fortunately, the arm controller and myself are right on cue with the release and back up.