Nightmare Repairs At Competition

[KrazyCarl92]

In 2011 our team used a crab drive from 221 robotic systems for our drive train. It was set up with a window motor steering all 4 modules together, but the window motor was overheating frequently at both of our regional competitions. This led to the thermal switch in the window motor tripping and our modules would stop steering as a result. At Connecticut we ended up switching out one of our modules for a spare, thinking that perhaps the axial shaft of the module was too "beaten up" (it appeared fairly marred as compared to what we expected). This turned out to be the wrong explanation, but we left the module in anyway since nothing had changed for better or worse.

Upon returning back home, we noticed a thin ring of metal that appeared shaven on the bottom plate of the swerve module. We then reasoned that the likely reason for the window motor issues was this rubbing between the bottom plate of the swerve modules and the bottom of the frame. We came up with a plan for how to deal with the issue if this was in fact the problem at Championship, since not being able to drive would be the worst thing that could happen. We gathered thrust bearings and material for spacers to be machined once we arrived if we found this was the issue.

On Wednesday night at Championships, we send in our five people: me, our pit mentor, our driver, a programmer, and the programming mentor. We used a piece of paper to see if the pieces of metal that we suspected to be rubbing were. 3 out of the 4 modules had the issue, so we had to add thrust bearings in the axle shafts, get the bronze bushings that the snap rings sat on turned down, and have several delrin spacers machined to the proper height. In 3 hours we ripped apart the entire drive train, got the machine shop to precision machine 20 parts for us, put the drive train back together, then ran some systems test. The drive train worked beautifully for the rest of the competition, and had our autonomous worked or a button on our controller (of course the all important minibot deployment button) not failed, we may have been selected for eliminations.

The best part was returning to the hotel and reporting back to the team what we had accomplished. One of the kids said completely seriously, "You mean you ONLY got the drive train fixed!?!?"