CIM Pinion issues in Toughbox

[GUI]

Today we were driving around testing our manipulator when a loud screeching noise came from the chassis. We checked everything out, and found that one motor on one side was very hot compared to the rest. We took the gearbox off of that side (we are using 2 CIMS in each of the Toughboxes, with one stage of gear reduction removed). When we disassembled the transmission, we found that the key in one of the pinions was sticking out at an odd angle and the pinion could rotate on its shaft (hence the screeching). The pinions were mounted as shown in the Toughbox assembly guide.

Upon further inspection, we deduced that the key slipped out from the between the teeth of the retaining ring, allowing it to remove itself from the keyway on the shaft and the pinion. Our solution to this problem was to cut the key so it is flush with the pinion and place a 1/4" washer at the end of the pinion before installing the retaining ring.

If you are using the Toughbox or any other gearbox that has the pinions mounted in a similar fashion, I strongly urge you to inspect your transmissions to ensure this won't be a problem.