The biggest problem I saw at the 2000 competitions is robots that don't have enough power to lift them off the ground. They would latch onto the bar, begin pulling up and either not make it off the ground, or would lift off the ground only to have the motor's thermal shutdown activate and they would slowly sink back down to the floor.
BIG MOE (365) was designed in such a way that it didn't have to lift up the entire 130lbs of the robot, only the drive chassis. All of the electronics and the air tank (no compressor in 2000) were mounted on the arm, and the drive chassis was basically only a frame to support the arm and a simple drive. When we hung on the bar (the hangers are painted green just behind the basket in the image below), we just used the arm, powered by 2 fisher price motors and a gear box (not easily seen in this picture), to pick up our drive chassis. Instead of doing a chin-up, BIG MOE just grabbed onto the bar and picked up its feet. This was our rookie year, and it was a lot of fun to do.
Oh yeah.. GO MOE! ! !!! !!!! !!