We had a question regarding wheels. Currently we are using the TETRIX All-Terrain Wheels (http://www.pitsco.com/TETRIX_All-Terrain_Tire), which seemed to work fine. They used climb the churros (at least up to the mid zone), but after some use, they seem to have trouble climbing the churros
Is it normal for these wheels to lose traction this quickly? If not, is there any way to increase traction? If so, how do these wheels compare to other wheels like the Andymark stealth wheels? Would you recommend the stealth wheels?
I’m not specifically familiar with these wheels (and the web site comes up with an “Oops!” page for me), but you should check the wheels for wear and contamination (e.g. oil or dust). I have had trouble at FRC and smaller-than-FLL scales with tires that got dirty and lost traction. Cleaning the tires has also helped at least one FLL team whose programs would not perform at competition like they did at the home field, due to dust on the wheels (the girls looked at me like I was out of my mind when I suggested it, but about an hour later, I got a hearty thank you). It is also possible that the churros’ surface is contaminated, but if that’s your problem, you’re likely to be faced with it at competition without such a simple solution.
Edit:
Yes, I see them now. I am wondering if those wheels might be better for climbing the grade on a bias than going straight up.
Finally, while I haven’t seen the FTC rules, and perhaps they disallow it, has anyone considered engaging the churros on the steep grade with hooks or grippers and climbing rather than (or in addition to) trying to roll up them?
I’ve seen a couple of teams take this route at MN’s first two qualifiers. They seemed to a have a somewhat easier time climbing than many teams with just a drive train.
The AM stealth wheels have very high coefficient of friction urethane tread and are very lightweight, so they are excellent at gripping the plastic slope of the mountain, however, like most gripping things they loose their grip once surface contact is lost when they start to elevate over the churros.
They do grip so well that even with ONLY either the front or the rear pair making good contact with he plastic, they will often still keep the bot moving forward/upward to the mid zone at least, as long as the bot stays pointed straight up slope and weight splits equally on the two down wheels. Once the bot begins to twist, then progress quickly stalls.
The big challenge is handling the effect from the axle elevation, caused by wheels contacting the churro bars with enough force/grip/torque to start elevating them off of the plastic (or not). Without some kind of wheel protrusions present and already engaging the churro(s) enough to resist slip and maintain forward climbing momentum, the slightest bit of axle rise instantly breaks most or all wheel grip on the mountain’s plastic surface, and often happens before the wheel protrusions (if any) have fully engaged the churro well enough to gain and hold a sold grip onto it,
The wheels rising up on churros also tends to trigger the remaining down wheels’ to lose grip as well, since even slight shocks and twists can cause them to break free of their hold on the plastic, especially when the slope gets steeper and the churro climbing wheel pairs lose good sync with their timing for their initial contact with the churros.
We decided to do a very unique and rather weird drive train concept with no real certainty that it would work. First time in six years we have ever gone custom wheels for either FTC (or FRC ). Turns out the gamble paid off big time. The paired wheel sets give both good rolling on the flats and sufficient hooking onto the churro bars to ensure climbing progress as long as front and rear wheel sets each stay reasonably well in sync laterally.
We added independent controls for all four wheel pairs to help with this.
