If one were to make some uncoupled wheels for a trolley to run on the underside of an RSJ, should one make the treads match the taper of the RSJ flange, exceed the taper (run on outside of flange) or be less than that or the RSJ (run towards the centre of the flange)?
I'm thinking that they should run on the outside of the flange for stability, but don't know for sure.
Mark Rand RTFM
Cylindrical wheels, with angled axes?
I don't know for sure either.
-- Peter Fairbrother
I matched the angle when I turned down the wheels of a Harbor Freight trolley to fit into 3" channel. It rolls well enough, hasn't gotten enough use to show any wear pattern yet.
jsw
What about a slightly convex profile on the wheel so it will find its own running position?
Match the taper of the RSJ.
Thanks all! I've just ordered the wheels (Parallel, but the right price :). I think I might go for Peter's suggestion and mount them at an angle to suit the RSJ flanges. It might be possible to turn them conical, but it'd mean dismantling and rebuilding them.
Making conical tyres for them would be silly. If I were going to do that, I could have made them compete from the same bar stock. The wheels cost less than my decent bar stock is worth!
Ho Hum. So many things to think about, so little brain to do it with...
Regards Mark Rand RTFM
I reckon you'll get the best life that way.
I was going to explain why, it's entirely clear in my head, but I've had a few tries at writing it down clearly, and failed miserably.
But thenI have seven botttles of sngle malt in front of me, having a wee tasting ...
:)
-- Peter F
The wheels should ideally be parallel and mounted at an angle. That means the peripheral speed is the same across the wheel width. However, most I've seem have tapered wheels as it's far easier and the speed error is negligable at the speeds and distances whe're looking at. One point, is the difference between RSJs and universal beams. Most UBs are refered to as RSJs but have parallel flanges. UBs tend to have replaced RSJs these days.
John
I'm going for parallel wheels, mounted at the same angle as the beam flanges. In this case, it's actually hanging a the end of a UB _from_ an RSJ, so the trolley will only fit one way up!
Mark Rand RTFM
I gave my neighbour 4 old wheel bearings from my AH Sprite, 6207 IIRC, and he used them for an overhead hoist on a RSJ and inclined them to suit the web angle, no problems at all.
Max load of 1.5T and max speed of 9000 rpm, I would hope they're OK. The only problem is keeping the dirt out.
John
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