Breaking gears in PG77

[AndromedaOne]

Hello,

Our team is using the AndyMark PG71 (am-2971) through a further 3 to 1 gear reduction to direct drive the angle of our ball handle. The ball handler is about 15" long and is also used to lift the portcullis. We use spring tension to compensate for the weight of the arm.

Originally, we used a PG188 motor with a direct arm drive (like a servo) to control the angle, but we shattered the gears in two motors before moving to the system we have now. The PG71 seemed to be more robust and provided the same performance with the 3 to 1 gear reduction. Unfortunately we experienced a gear failure at competition.

Under the normal operation (ball handling and lifting portcullis) my calculations show that the combination PG77 and 3 to 1 gear reduction gives a good balance of speed vs power and does not come close to the failing torque of the motor (39ft-lbs). I think the issue is that in competition the arm can be hit and impart forces in excess of 39ft-lbs.

Has anyone else had this issue and how did you deal with it? The only thing I can think doing is going with a more robust gear box, but that will be hard to find and retrofit at this point. Given we had only one failure in two competitions we may have to live with it, but I though I would ask in case there is something we can do to improve the situation.

Thanks,
Bill