[EricH]

Originally Posted by ShaneP

The shaft they turn keeps them in place, locked up against the square tubing (in our case, 1.5"x1"). Shaft collars keep the transmissions from sliding out (off the shaft).

And if we don't have a vertical member that will work in the right place, it's pretty easy to turn some plate aluminum of reasonable thickness and some angle aluminum into a pair of mounting brackets.

1) Cut the plate to shape. You'll probably want some form of triangle. Note: Helps to have at least one side exactly the same.
2) Locate and drill a hole for the axle. Try to get it in the same place on both plates.
3) Attach the angle aluminum to the plates.
4) If more weight is needed elsewhere, leave about 1/2 inch all around the edge of the plates and the holes in them. Remove excess material inside that as needed.

We did that in 2004 for a winch system similar to the one Eugene posted. Started using handy vertical frame members in 2005, when they weren't moving relative to the base of the robot.