[RRLedford]

We had a narrow 6-wheeled KOP setup tank bot designed to hang most of its width off the side of the bridge so that long bots could drive past us as we balanced. We had a plastic groove on our underside that engaged with the side rail to keep us aligned with the bridge rail, but without gripping it.

So going up the bridge, we only had three remaining wheels still on the bridge to get us up, and, since the center wheel was slightly lower, only two if these three would be touching the bridge at any one time. We did have most of our mass severely side shifted to keep it above the bridge, and had extra ballast there too, to make this work fotr traction, but despite the shifted weight over the two touching wheels, the 2012 KOP treaded wheels stilldid not have enough traction. We were spinning wheels like crazy just to barely make it up the bridge.

We then bought some older, close out Andy Mark wheels (from 2008 I believe), which had no tread and seemed to be a fairly soft gray urethane material.

We placed two of these wheels on the front and middle of the side that pulled us up the bridge. Traction improved significantly. We left the treaded KOP 2012 wheel on the rear, and took advantage of the tread notches to make a brake from a long piece of light angle aluminum as a pivot bar with a 180 servo at the long end and a horizontal through bolt whose tip stuck into the tread notch when servo activated.

Having a brake was critical for us mastering the 3 bot bridge balance, which we accomplished three out of the only four times we ever attempted it.
Unfortunately, those successes were only in the pit practice area, prior to quarter finals, and our partners ended up too nervous to attempt the triple bot balance in actual competition. The Midwest regional ended up with no alliance ever doing a triple balance, so our successful three in the practice area (<30 seconds too) were the only ones a few people at least got to see. The brake grabbing the tread notch was a fantastic idea, easily implemented, and our three bot balances would have been impossible without it.

-Dick Ledford