Axial bearing

[sleepygit]

What's the bet way of doing the axial bearing in the photo below?

It's basically a solar panel mounted on a trailer, and needs to be able to rotate by 180 degrees.
The total weight of the panel will be about 100kg.

Ideas so far cosidered:

a) just have to plates as in the drawing below, with a large bolt holding them together (not done up too tight). And have a grease nipple.

b) have some sort of bearing (either a tapered wheel bearing type thing or a thrust bearing) between the two plates, again with a big bolt.

c) use two bits of tube that fit inside each other in combination with either a) or b)

Ideas? Trying to keep it simple but also easy(ish) to rotate.

 

[Maker]

You want two bearings with some distance between them. You might get away with just deep groove bearings, you'd have to look up the axial load rating for whatever bearing suits your shaft size.

 

[Pete.]

Weight is nothing compared to the potential wind loading. I've seen lighting towers with nothing more than two flat plates with holes in them, sometimes with plastic shims between.

 

[Gareth J]

In this case, the high speed and accuracy of a machined bearing are pointless. Two fairly loose fitting tubes and the plates will work well. Or even a tube inside the box section might work well; iirc, 1" bore pipe is a nice sliding fit in 1.5" box (or whatever the metric versions are)

 

[8ob]

I will post up a picture of a chipper chute assembly, easy to copy and perfect for this application. Uses a pinch bolt and ptfe washer.

Bob

 

[Agroshield]

a) just have to plates as in the drawing below, with a large bolt holding them together (not done up too tight). And have a grease nipple.

Two PTFE or UHMW plastic rings between the steel flanges. No grease nipple. Rain for lubrication. Nylok nut to set tension. Bolt head welded to end plate.

Two design issues: how do you access the nut to set the tension; how do you ensure rotating the panel clockwise does not try to tighten the nut and rotating it anticlockwise does not try to loosen it.

 

[sleepygit]

Weight is nothing compared to the potential wind loading. I've seen lighting towers with nothing more than two flat plates with holes in them, sometimes with plastic shims between.

That's exactly the sort of thing. Off to Google lighting tower parts diagrams...

 

[sleepygit]

Two PTFE or UHMW plastic rings between the steel flanges. No grease nipple. Rain for lubrication. Nylok nut to set tension. Bolt head welded to end plate.

Two design issues: how do you access the nut to set the tension; how do you ensure rotating the panel clockwise does not try to tighten the nut and rotating it anticlockwise does not try to loosen it.

Is it better with two plastic plates, or just a single one?

 

[dan.taylor.1]

A bit off topic, but can you buy thin ptfe sheet, like sub 1mm thick? Had to replace some shims on my stones aw guard assembly recently and they were just a paper thin ptfe washer.

 

[voipio]

If using a sliding tube method for the rotation bearing, make sure that the tube with the panels on it is captive, and doesn't just rely on gravity, since a "tail wind" would produce a lifting force on the panels.

 

[mtt.tr]

I will post up a picture of a chipper chute assembly, easy to copy and perfect for this application. Uses a pinch bolt and ptfe washer.

Bob

This is what I would use,.

 

[Agroshield]

A bit off topic, but can you buy thin ptfe sheet, like sub 1mm thick?

PTFE Sheet Roll Flexible Plastic Plate Thick 0.2/0.3/0.4/0.5/0.6/0.8/1/2/3/4/5mm | eBay

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www.ebay.co.uk

Maybe a gasket-making supplies place would have it.

 

[Agroshield]

Is it better with two plastic plates, or just a single one?

My thought on suggesting two is that plastic will rotate against plastic. With a single one, steel will rotate against plastic somewhere in the assembly.

 

[sleepygit]

My thought on suggesting two is that plastic will rotate against plastic. With a single one, steel will rotate against plastic somewhere in the assembly.

I wonder if I would need to somehow fix the ptfe to each of the plates, or if the friction between the ptfe and the galvanised surface would be so much more than the ptfe / ptfe surface, that I wouldn't have to worry.

Or I wonder if a PTFE washer and a stainless steel washer would be a better option (will two sheets of ptfe try and stick to each other?)

 

[bricol]

My thought on suggesting two is that plastic will rotate against plastic. With a single one, steel will rotate against plastic somewhere in the assembly.

I'd rather have steel against plastic, than plastic on plastic.

 

[sleepygit]

Looks like ptfe/ptfe is fine

Teflon Slide Bearings

Slide Bearing Assemblies, Fluorogold® and Teflon® slide bearings

www.thesteelsupplyco.com

 

[sleepygit]

I'd rather have steel against plastic, than plastic on plastic.

That was my original thought. Maybe a ptfe 'washer' and a stainless steel 'washer'.

Looks like both options are acceptable

 

[bricol]

If I was being posh, I'd have a flanged plastic bush top and bottom of the support tube, drop the spindle down it, and bolt on a suitable washer at the bottom to retain it - with suitable drain holes to let the rainwater out. Igus do cheapish plastic bushes if you don't have material or facilities to make one.

If I was paying for it myself . . . as has been suggested, tube in a tube, smother in grease so it doesn't seize from rust. Make mental note to regrease every year. In ten years apply angle grinder to free it up and regrease.

 

[sleepygit]

If I was being posh, I'd have a flanged plastic bush top and bottom of the support tube, drop the spindle down it, and bolt on a suitable washer at the bottom to retain it - with suitable drain holes to let the rainwater out. Igus do cheapish plastic bushes if you don't have material or facilities to make one.

If I was paying for it myself . . . as has been suggested, tube in a tube, smother in grease so it doesn't seize from rust. Make mental note to regrease every year. In ten years apply angle grinder to free it up and regrease.

We will be making a few hundred of them so I need something that's easily reproducible - hence liking the idea of laser cut plates and not messing around with a spindle.

I think I will give the plates / washer combo a go, and if that's no good, I'll have to redesign it with a spindle.

 

[Pete.]

A commercial venture? That stuff needs design.