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Post by runner42 on Oct 15, 2023 4:35:31 GMT
I want to make a rolling road for a 5" gauge locomotive with 6" coupled wheels. So what bearing size would be required?
In specifying the bearing size the outside and inside diameters and thickness would be welcomed.
Brian
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SteveW
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Post by SteveW on Oct 15, 2023 8:38:20 GMT
Would suggest go for whatever bearings you can get cheap that collectively will support the load and be appropriate to fit your frame and the track rollers you'll need and certainly nothing much more than 10mm inners. You might also consider needle bearings as its unlikely the distances covered will be very great.
Would certainly go for full width rollers for the driving wheels with a compatible rail-like 'track' profile where needed. The perfect solution would be to couple the rollers which will help the loco's connecting rod's action while the thing runs-in.
Perhaps consider making the rollers and variable pitch ready for the other track gauges/locos to make the whole thing more saleable.
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Neale
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Post by Neale on Oct 15, 2023 8:41:01 GMT
I would probably look at so-called skate bearings. Standard size, made in their millions for roller skates and so on, dirt cheap, and the right kind of speed and load for a model rolling road. Various qualities and shield options, if that's a concern. A fellow club member has just made a rolling road using them - looks fine.
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SteveW
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Post by SteveW on Oct 15, 2023 8:48:43 GMT
Consider these things - Pillow Blocks or similar as they'll solve the mounting problem and reduce the frame design to a couple of lengths of angle iron and some spreaders.
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uuu
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Post by uuu on Oct 15, 2023 8:56:44 GMT
I got mine from CMD: WebsiteThey do all gauges, I suspect with the same bearings. Fabulously overengineered and chunky. Mine are 6203RS, 40x17x12mm (ODxIDxW) Wilf
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Post by Jo on Oct 15, 2023 16:07:42 GMT
If you buy chinese ones you will be able to turn their outsides to rail profile Jo
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jo479
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Post by jo479 on Oct 15, 2023 18:44:48 GMT
I use ArcEuro for my bearings
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uuu
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Post by uuu on Oct 15, 2023 19:17:57 GMT
I like Simply Bearings. They have a full choice, budget and premium, and they deliver free for orders over £5. Wilf
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Post by David on Oct 17, 2023 9:58:08 GMT
A recent G1 society mag had an article talking about how the usual setup of a bearing in front and behind each wheel lead to lumpy running. The author thought it was because the wheels were trying to climb one of the bearings. Anyone have experience or opinion on that?
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uuu
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Post by uuu on Oct 17, 2023 11:12:36 GMT
I've not noticed this. But I could think of two other reasons that a loco might run less sweetly on rollers, than on the track:
If the coupling rods and bearings have slop in them, the coupled axles might fight a bit, alternately being behind, and in time with the driven axle. Having linked supports, as suggested by SteveW, might help here.
On the track, the inertia of the moving loco will have a smoothing effect, like a flywheel on a stationery engine. With any load you're pulling adding to this. You only have the wheels and rods to damp any unevenness when running propped up.
Wilf
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SteveW
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Post by SteveW on Oct 17, 2023 11:46:44 GMT
A recent G1 society mag had an article talking about how the usual setup of a bearing in front and behind each wheel lead to lumpy running. The author thought it was because the wheels were trying to climb one of the bearings. Anyone have experience or opinion on that? I can understand this if the wheels are running on their own isolated rollers/bearings. On a track the wheels, left and right, are coupled together by the planet beneath us via the track and sleepers. The only way to emulate this is to use solid rollers for each axle. To fully support the action of the coupling rods and maybe confirm consistent quartering the rollers need to be sync'ed some how but is perhaps less important. Remembering that the loco's tapered wheel treads provide centreing on the track and a differential action on the curves each axle set have to be running on a single roller supporting both wheels to maintain stability. (314)
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SteveW
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Post by SteveW on Oct 17, 2023 12:39:32 GMT
Another thought being the simplest rolling track can be emulated simply using a couple of bricks. Just need the wedge one under the front and the other under the back.
Agreed, this approach does not fully model proper running but then neither does having the locomotion running on independent ball races.
(332)
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Post by ettingtonliam on Oct 17, 2023 13:21:28 GMT
And maybe wedge the axleboxes up to running height, about mid way up the horns?
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Post by chris vine on Oct 17, 2023 14:44:52 GMT
Unless the axle boxes are to scale with only the top halves as bearings, then if you are going to wedge them half way up the horns, you could always do as I have done many times with Bongo: Support the loco and run with the wheels in the air.
It will be much quieter that way as the wheels on the ball bearings are quite noisy.
Chris.
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uuu
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Post by uuu on Oct 17, 2023 14:48:04 GMT
If your loco is an 0-4-0, you could make a giant hamster wheel, and resolve all these issues.
Wilf
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Post by runner42 on Oct 19, 2023 5:25:38 GMT
Unless the axle boxes are to scale with only the top halves as bearings, then if you are going to wedge them half way up the horns, you could always do as I have done many times with Bongo: Support the loco and run with the wheels in the air. It will be much quieter that way as the wheels on the ball bearings are quite noisy. Chris. I thought the purpose of the rolling road was to put some braking effect on the wheels to show that the locomotive has the ability to travel under it's own steam. This is not fully representative but would show if piston blowby is significant. Brian
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Post by chris vine on Oct 19, 2023 6:02:12 GMT
Hi Brian,
I don't think there is enough friction in the ball bearing/rollers to have much effect in that way.
Now, a rolling road with dynamometers attached to each roller - that would be an interesting project. Roger??
Chris.
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uuu
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Post by uuu on Oct 19, 2023 7:24:07 GMT
...I thought the purpose of the rolling road was to put some braking effect on the wheels to show that the locomotive has the ability to travel under it's own steam. This is not fully representative but would show if piston blowby is significant. Brian This is not a feature of the commercial units I bought, nor of the homemade ones I've seen. We've mostly used the rolling road to check things like valve events, function of axle pump, listen for odd knocks etc. To add a bit of load, if needed, we've part-applied the loco brakes. Wilf
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Post by andyhigham on Oct 19, 2023 8:19:08 GMT
Hi Brian, I don't think there is enough friction in the ball bearing/rollers to have much effect in that way. Now, a rolling road with dynamometers attached to each roller - that would be an interesting project. Roger?? Chris. When I was at school we were learning about torque and power in a physics lesson. We did test on the schools Mamod 2 cylinder engine and my 1 cylinder Mamod. The test rig comprised of a drum of known diameter with a string attached. The engine would wind the string onto the drum lifting a weight. By increasing the weight to the point where the engine stalled the torque could be calculated Lifting a known weight and measuring the time taken to lift it a known distance the power can be calculated. The 2 cylinder Mamod produces approx double the power of the Mamod single
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Post by brucevoelkerding on Oct 20, 2023 23:48:29 GMT
Brian - I stumbled across the Design for a Rolling Road in Model Engineer Volume 184 No. 4122, dated 16.Jun 2000. Gordon Helps of Buxton MES describes a very elegant Design. His Locomotive is a 5" gauge 4-6-0 with 7.125" diameter Drivers. The Rollers are qty 2 per Driver like the Concept listed above by Wilf. Gordon uses 1.50" dia x 3/8" wide Bronze Bushed Rollers sandwiched between qty 2 1/8" steel Plates. The distance between a Roller Pair is 2.00 inches. It appears Gordon's Rail is 10mm x 40 mm which is set up off his Bench. Each set of Rollers can be clamped on the Rail to suit the Locomotive. Gordon mentions another Article in Model Engineer No.3929, dated 18.Sep 1992, where he describes his "Assembly Rails".
That being said, a number of Changes could be made to simplify construction - o leave Side Plates rectangular, not triangular, o convert to a Ball Bearing, o I also wonder, if the Side Plates are clamped to the Rail, why not just use qty 1 Ball Bearing per Driver ?
Bruce
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