Posted by Andy Baker at 02/26/2001 9:09 AM EST
Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.
In Reply to: Re: Tank treads and specialty wheels
Posted by Jim Meyer on 02/26/2001 8:24 AM EST:
: A few tank treads are double sided timing belt. Some, like the Techno-Cart, appear to use small metal plates fastened to a roller chain.
This is the second year for team 45 to use metal treads. We used them back in '99. Ours for this year are drastically different. Here’s how we did it:
We took 35 chain from Small Parts, and welded on steel angles on either side of the chain at every 6th full link. This was not easy. We had to first make a welding fixture, and then do some practicing to get some decent welds and figure out if the welds would hold.
At the same time, we took 0.060 steel sheet, cut it into 1.5" squares, and then bent up the sides to look like a shallow “U” shape. The corners were ground off and the entire “cleat” was sanded to make it smooth.
The cleats have two clearance holes in them that match up with two holes on the steel flanges on the chain, and we used #6 button heads with nylock nuts to fasten them on.
One note… we had to de-grease the chain before welding and then re-oil it after all of the flanges were put on.
After much practicing, we noticed no carpet damage. We stared to see some wear on the ramp where we are continuously driving over it… kinda like a discoloration of the carpet threads to a lighter color… but I suspect that this is typical for any team’s bridge that got alot of traffic.
These treads do cause splinters to the 4x6 under the center barrier, but only if we are really banging into the boards. If we take it easy while going over the board, then a few marks are made, but splinters are few and very small. It is not good for our robot to be banging against the board anyway, so our drivers are told to take it easy.
We have noticed some damage to the treads and welds. So far, we’ve just taken a pair of pliars and bent the damaged parts back into position. We made two sets of backup treads, so if the treads on the 'Kart get too bad, we’ll swap the whole track out for new ones.
I don’t know if our efforts will be worth it… but we had fun making these treads, that’s for sure. One great thing about the chain/treads is that efficiency losses are low, in comparison to a timing belt. I don’t know exact numbers, but I would assume that there are less losses in a chain drive system compared to a timing belt system.