Traction tyres

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muggins
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Traction tyres

Postby muggins » Fri Jun 18, 2021 1:32 pm

What is actually the real deal with traction tyres? I've never had a loco with traction tyres since the Airfix GMR 14XX I had 40 years ago, which was probably when I first learned that they are a Bad Thing on account of how they clag up your track and generally cause problems.

But do they? Given clean track and a regime of regular thorough track cleaning, what is the actual issue with running a modern traction-tyre-equipped 00 loco (on DC, if it makes any odds)? The more I think about this, the more I'm wondering if much of the perceived issue with traction tyres is prejudice based on hearsay evidence, so ... anybody running traction tyres and not having problems?

Byegad
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Re: Traction tyres

Postby Byegad » Fri Jun 18, 2021 1:40 pm

Several dozen out of my 300 N gauge locos have them, on DC I see no issues at all with them.

Bigmet
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Re: Traction tyres

Postby Bigmet » Fri Jun 18, 2021 2:13 pm

The problems come in 3 distinct categories.

Formulation. There are suitable material choices that work well, cause no dirt and last indefinitely; what's more these can be translucent so really aren't visible unless looked for. Then there's soft gummy stuff that dirts, stretches and slips on the tyre, meaning that spares have to be purchased. Guess which is universal on RTR OO?

Dynamics. Poorly designed mechanisms with traction tyres on both wheels in a wheelset can be vulnerable to derailment, this problem increasing with wheel diameter.

Power collection. The most effective wheels for current collection are those that are driven, primarily because they also have the most weight bearing on them. An insulator on the tyre is a major loss to potentially reliable current collection.

(Not a problem for most modellers, but the effectiveness outdoors is minimal tending to zero. Between the inevitable dust rapidly coating the tyre surface, and the total ineffectiveness if the railhead is even damp, they are a non-starter.)



On track dirt, I made a systematic comparison donkey's years ago, and good track cleaning will keep the railhead dirt at bay. But much less cleaning is required if all hard metal wheels are used on a layout, the ratio about 10:1. At the time I had access to a very comprehensive suite of physical and chemical analytical gear and was able to pick up components of the traction tyre and plastic wheel polymer formulations in the track dirt, so had no doubt these were the source of the majority of the organic gunk on the railhead.

If you like what traction tyres offer and the cleaning is an acceptable trade off, that's fine.

muggins
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Re: Traction tyres

Postby muggins » Fri Jun 18, 2021 2:24 pm

Cheers gents. Hmmm. Given the circumstances in which many folk seem to run their toy trains (and note here I'm not saying a word about Sam's Trains and the like), I can quite see why manufacturers resort to traction tyres for some wheel arrangements, but I'd rather assumed that by now they'd have come up with a better compound than what might might as well be recycled rubber bands. As Bigmet says, there's certainly plenty of rubbery stuffs that would work.

I think perhaps they're still not for me ...

Bigmet
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Re: Traction tyres

Postby Bigmet » Fri Jun 18, 2021 4:09 pm

Nearing 30 years since Bachmann demonstrated in RTR OO the virtues of high mass combined with a drive to both bogies in their 'Peak', you really would hope that most folks had appreciated the benefits, compared to the motor bogie and rubber.

As for RTR OO steam and rigid chassis diesel models, schemes to include more metal for increased mass have been improving all the while, which is very welcome.

Superior engineering is what's required when there is a balance problem to solve, and 4-4-0's that pull well now seem to have been mastered. As for the delightful scheme of matched tyre speed on the Stirling single making it effectively a 4-4-0, too much good cannot be said.

It's the front coupled family of 0-4-4T and 0-4-2 that still require attention, and a light motor (coreless!) and DCC socket mounted to rear, allowing solid mass above the coupled wheelbase, has yet to be demonstrated in RTR OO.

And we are shortly to see how well Bachmann have contrived on a small 2-4-0 which was noted for its tractive powers...

muggins
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Re: Traction tyres

Postby muggins » Fri Jun 18, 2021 5:06 pm

Bigmet wrote: ... And we are shortly to see how well Bachmann have contrived on a small 2-4-0 which was noted for its tractive powers...


Pray tell, gentle Sir, what is this of which you speak?

Bigmet
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Re: Traction tyres

Postby Bigmet » Fri Jun 18, 2021 5:23 pm

Commissioned from Bachmann by Locomotion and Rails of Sheffield, the LNWR's 'Jumbo' 2-4-0.
http://www.locomotionmodels.com/coming- ... dwicke.htm

muggins
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Re: Traction tyres

Postby muggins » Fri Jun 18, 2021 5:31 pm

Thank you sir. Having seen the price of it, I shall probably be shaking my head in wonder for the rest of this evening ...

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Peterm
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Re: Traction tyres

Postby Peterm » Sat Jun 19, 2021 12:54 am

muggins wrote:Thank you sir. Having seen the price of it, I shall probably be shaking my head in wonder for the rest of this evening ...

:shock:
Pete.

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Mountain
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Re: Traction tyres

Postby Mountain » Sat Jun 19, 2021 11:53 pm

The main problems with traction tyres come when one has a garden railway as when traction tyres get damp or wet they slip and can come off the wheels.
With indoor layouts they are an advantage as they give superior pulling power at the wheels. The downside is that the traction tyre means that current collection can't be used on those wheels.

I fully understand why they use traction tyres on some small lightweight locos though I would rather have etter current collection ... But it can be an understandable compromise. It does puzzle me why traction tyres are seen on some all wheel drive diesels though. Why? They already have strong pulling power.

Mike Parkes
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Re: Traction tyres

Postby Mike Parkes » Sun Jun 20, 2021 11:20 am

The other downside with traction tyres is how dirty they make the rail surface - banish traction tyres and all plastic wheeled rolling stock, ensure all metal wheels are clean and the time spend having to clean the track falls significantly.

Bigmet
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Re: Traction tyres

Postby Bigmet » Sun Jun 20, 2021 12:43 pm

Mountain wrote:...It does puzzle me why traction tyres are seen on some all wheel drive diesels though. Why? They already have strong pulling power.

That was just a 'hangover' from past practise with motor bogies by Lima (class 67) and Hornby (class 50) now nearing 20 years ago, and was swiftly dropped as unnecessary. Bachmann have never put traction tyres on theirs, probably benefitting from experience in the North American market, and neither have Heljan; and none of the more recent OO entrants have done so, as far as I am aware.

(Bachmann from their start in RTR OO about 1991 should get the credit for leading the charge in eliminating traction tyres from UK OO, making their locos heavy enough to pull well.)

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Mountain
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Re: Traction tyres

Postby Mountain » Sun Jun 20, 2021 8:19 pm

That is the key. Finding ways to add enough weight in the right places. Not always easy.

Bigmet
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Re: Traction tyres

Postby Bigmet » Mon Jun 21, 2021 11:04 am

Mountain wrote:That is the key. Finding ways to add enough weight in the right places. Not always easy.

The increasing use of cast metal, both for weight within, and for the exterior of the bodies of steam locos, has been applied to good effect by Bachmann, Heljan, Hornby, Oxford and Rapido, and quite possibly others whose products I have yet to sample. Hopefully selective incorporation of casting for steam loco bodies will become the norm, especially on smaller tender locos and 'awkward' front coupled tanks.

Between this and an intelligently arranged mechanism very few classes need present difficulties. What has particularly impressed me lately are perfect fits achieved between exterior cast and plastic components of body shells, so that there is no restriction preventing the designer from using the most suitable material to deliver a model of best appearance with enough weight for good traction.


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