If you look at our gallery on our website
www.179swampthing.org you'll see some CAD pictures as well as close-ups of the mechanisms. There are (2) 3/4" bore pistons with 1" strokes that actuate the rear grippers on a pivot point about 3" up from the point the piston is connected to it (so there isn't much leverage - but you don't really need it). The forward pinchers are static. Then this whole assembly is welded together and pivots on the chasis by another 3/4" piston with 5" stroke. Its hard to see and explain, but hopefully the pictures will help.