Roller arm - Wheel

[ESPbomb]

Hello World,
I am in the process of designing a roller arm, which sucks in the tube with tread, and there are mixed views as to one aspect. One party thinks we should have an idle wheel at the back to minimize friction with the frame, and one party believes that if the frame has a curve at the back, a wheel is not needed.
Opinions?

[Chris is me]

What would a wheel at the back accomplish? When would it spin and when wouldn't it? How would this spin reduce friction?

[ESPbomb]

Originally Posted by Chris is me

What would a wheel at the back accomplish? When would it spin and when wouldn't it? How would this spin reduce friction?

Well, a wheel at the back would be spun whenever the tube was rotating inside the tread. The idea is that we can run the tread in the same direction to rotate the tube vertically so it can be put on a peg. The wheel is there so that the tube will not be popped.
ESP

[artdutra04]

Originally Posted by ESPbomb

Well, a wheel at the back would be spun whenever the tube was rotating inside the tread. The idea is that we can run the tread in the same direction to rotate the tube vertically so it can be put on a peg. The wheel is there so that the tube will not be popped.
ESP

Prototype it to see if it'll work/is needed.

[sgreco]

Originally Posted by ESPbomb

Hello World,
I am in the process of designing a roller arm, which sucks in the tube with tread, and there are mixed views as to one aspect. One party thinks we should have an idle wheel at the back to minimize friction with the frame, and one party believes that if the frame has a curve at the back, a wheel is not needed.
Opinions?

in 2007 my team had pretty much the exact design that you are speaking about. Our prototype had an idler in the back. We built the real thing, left off the idler for weight purposes, and found it made no difference at all. Just make sure it isn't rubbing on anything with friction, and if it is, coat it in any kind of tape you can find with a low friction surface. That's what my team did in 2007, and we had no problems with tubes binding in the back of the claw.

(Just avoid sharp edges, but that's pretty obvious).

[Colin P]

Originally Posted by sgreco

Our prototype had an idler in the back. We built the real thing, left off the idler for weight purposes, and found it made no difference at all.
(Just avoid sharp edges, but that's pretty obvious).

I was thinking an idle wheel wouldn't really affect performance much. We're using the same design and we never even considered an idle wheel because it does about as much work as a slick surface.