[fox46]

It's not that teams have done a poor engineering job or are overrating their components. BB clearly states that the gearboxes are not designed to take more than 35 lb-ft of torque. The mechanism on our robot is neutrally biased by a gas shock- you can lift the arm with one finger however, the gearboxes are just not robust. They work for a bit and then parts start wearing, the aluminum galls and things come apart.

Their gearboxes, especially those 128:1 and greater produce a TON of torque. The only think keeping the ring gear from spinning free are four 3/32" roll pins pressed into aluminum, loaded in bending against two small flats! its like trying to tighten a 12 sided aluminum bolt with a crecent wrench. This could have easily been avoided by keying the faces between the end plates and ring gear.

The output shaft although 1/2", transmits torque through a 3/8" diameter shoulder with two flats machined on it. The stress concentration is so high at the edges of these flats that it distorts the final reduction carrier that it fits into and rounds it out. I don't understand why they wouldnt machine the final reduction carrier and shaft as one and avoid this problem all together.