[Kevin Sevcik]

You could work out the output torque of the trannies yourself to see. BB gives you the stall torque for each of them. The RS-775 has a stall torque of 0.588 ft-lb. The RS-395 has a stall torque of 0.0867 ft-lb. Multiply it out and see.

Also, don't count on the trannies to not backdrive. The new P60s from BB are pretty smooth, and the BEST you could hope for is for it to stick in place statically... right up until anything bumps it. So looks for other options to keep your arm stationary. Counterweight and counterbalance mechanisms work well here. Or put a sensor on it and tell your programmers to write a PID loop for it.