[BBray_T1296]

Just because your arm is lifting many pounds, does not mean your motor has to handle the brunt of the load.

You could balance/offset the load via a counterweight.

I'm not necessarily talking about a strictly mass-based counterweight either. Attached is a graphic representation of our 2011 robot, minus some irrelevant complexity**

While we were only lifting the arm itself and an inner tube, this setup could be beefed up with real springs and more powerful motors

The arm was a simple translating parallelogram "4-bar" arm, with surgical tubing connecting two opposing corners. When empty-handed, the arm (without motors) defaulted to straight forward (purple). With a tube, 95% of the weight* of the assembly was on the tubing, allowing just 2 window motors to easily and quickly lift the tube into the scoring position. The motors actually had to "fight" to put the arm in the lowest position, though the "brake" setting on the motor controllers was enough to combat that

If your arm was to lift, for example, 50lbs, I would set the virtual counterweight (tension) to maybe 25lbs. That way, unloaded, it takes 25lbs* to lower the arm, and loaded, takes 25lbs to lift the arm. Halving the load at the expense of doubling the load time is well worth the trade off. You will have a much easier (and lighter) time building a mechanism that is not as beefy.

*in the straight out position

**In the real photo there is also a wrist mechanism, which explains much of the difference between the concept drawing and real deal**