View Single Post
  #17   Spotlight this post!  
Unread 05-06-2010, 18:31
joek's Avatar
joek joek is offline
Team Welder and CAD tech
FRC #2052 (KnightKrawler)
Team Role: Mechanical
 
Join Date: Jan 2009
Rookie Year: 2009
Location: Irondale H.S.
Posts: 231
joek is an unknown quantity at this point
Re: Chain driven vs Direct drive mechanum

Quote:
Originally Posted by Tom Line View Post
A correctly set-up chain drive should require zero maintenance. We use 25 chain and didn't have a single break or issue, nor did we ever have to adjust it.

The trick is to hand grind (or cnc your chassis) so that you have good alignment.

The other trick is to develop a tensioning system that doesn't add friction, and keeps the chain snug. Snug, not TIGHT. Tight chain is bad. Snug chain with just a hint of play is perfect.

Our 8 wheel traction drive train had more problems with the plaction wheel fasteners working free then breaking off. We were using grade 8 fasteners and locknuts. A bit too much forward and back working I guess.

I wonder if it would be a good idea for andy mark to put 8 more holes on their chain sprockets and 8 nubs on their wheels so the two 'key' together.
the fact that they were grade 8 was probably the problem, hard bolts don't bend, they snap, and aren't very forgiving of shock forces, grade 6 is probably a better option and 8 more holes would weaken the sprocket pretty severely.

i've never heard of a team who have had issues with bolts snapping before, we never have that problem, but then again, we've never used traction drive, only mechanum and a couple tank drives.
__________________


2012 Record (13-2-0)
lake superior regional finalists- thank you WAVE (2826) and Blue Twilight (2220)