[Paul Copioli]

You could use the window motors from my post earlier. Or, you could use the van door. Instead of telling you what spool size to use, I will let you figure it out with some help.

O.K., here is the van door motor torque equation:

Torque = (-34/75)*Speed + 34

Speed (angular velocity) is in RPM and torque is in N-m. At max power your speed and torque are approximately 38RPM and 17N-m, respectively. Let's assume you want to be able to pull up yourself and another robot at max power(in case your opponent is trying to hold you down) so that is 260 lbs.

Assume no gearing, just a spool right on the Van door shaft. What diameter of spool do you need? After you figure that out, then tell me how fast you would be going at max power. Then tell me how fast you would be going if you were only lifting 130 lbs.

Equations of interest:

1. Torque = Force * Diameter/2

2. Velocity = Angular Velocity * Diameter/2

After you give it a shot, I will help.

-Paul