[DonRotolo]

[quote=Matt H.;686342] so a 40 in-lb spring would be able to just barely support a 40lb load at 4in from the point of rotation.
QUOTE]You mean a 40 lb load at 1 inch (or 10 lb at 4 inches). 40 lb at 4 inches is 160 in-lbs.

Torque in ft-lbs is exactly what it sounds like - a force of one pound at 1 foot from the center of rotation.

If you pushed with the same force at 2 feet from the CoR, you'd have 2 ft-lb, and you know that makes sense from when you use a wrench to tighten a bolt - a longer wrench puts more force on the bolt with the same push.

If you decided that 20 pounds would push a ball to a certain height, and your torsion spring was 40 ft-lb at 180 degrees of wind-up, then an arm two feet long would push with 20 pounds (for the first instant). As the spring unwinds, the force decreases linearly to zero at no rotation.

Does that make sense??