[sanddrag]

I don't have any calculations but I can provide a little story about our experience with the van door. Here is a picture of our 2004 robot with Van-Door Actuated arm. http://team696.com/images/2004/IMG_0141.jpg In the pivoting portion of the arm there is a heavy 2" bore 12" stroke pneumatic cylinder. We geared down the Van door motor approximately 3:1 for FIRST Frenzy. We tried lifting a tetra with a 2.2:1 reduction in the same setup (heavy pneumatic cylinder still in place) and the motor could just barely hold the arm with tetra on the end level at stall. We then tried a 4.5:1 reductin and it lifts a tetra just beautifully.