Traction tyres - pointless??

Discuss Hornby Model Railway products and related topics here. This includes (Lima, Rivarossi, Jouef, Electrotren).
Sc0tty
Posts: 77
Joined: Wed Dec 17, 2014 7:27 pm

Traction tyres - pointless??

Postby Sc0tty » Fri Jan 02, 2015 12:45 pm

Guys,

Can traction tyres be removed from any locos that have them installed? I don't see why some locos have them and some don't !

Do real life engine have traction tyres?? I thought tractive force was all to do with mass vs aerodynamic drag etc..

User avatar
Dugie Diesel
Posts: 84
Joined: Thu Mar 19, 2009 10:47 am

Re: Traction tyres - pointless??

Postby Dugie Diesel » Fri Jan 02, 2015 1:17 pm

I think its most of the older models that have traction tyres now, most modern models rely on the weight and the motor being in the loco rather than the tender so there is more grip. I have a Lima 108 that had traction tyres and i ran that without the tyres for ages with no real problems but the grip was lacking on inclines. Probably the best way to remove them is to fit replacement wheels sets but then you would need to add additional weight, of course this all depends on which model it is, ie a dmu, steam engine or diesel as the driven wheels and motor arrangement differs.
Don't mess with my Choo Choo.......

Lofty

Re: Traction tyres - pointless??

Postby Lofty » Fri Jan 02, 2015 1:23 pm

Sc0tty wrote:Can traction tyres be removed from any locos that have them installed?

The wheel with the traction tyre fitted is obviously smaller than the others (the traction tyre brings it up to size) if you remove it there is an obvious mismatch

User avatar
Bufferstop
Posts: 11039
Joined: Thu Mar 11, 2010 12:06 pm
Location: Bottom end of N. Warks line

Re: Traction tyres - pointless??

Postby Bufferstop » Fri Jan 02, 2015 2:19 pm

Sc0tty Most steam locos had tyres, steel ones, fitted to the wheels then machined to profile. The smaller wheels of diesels and multiple units are less likely to have tyres, the profiling can be applied direct to the wheel, which, upon scrapping, goes back in the furnace to cast new ones.
Growing old, can't avoid it. Growing up, forget it!
My Layout, My Workbench Blog and My Opinions

User avatar
Emettman
Posts: 2353
Joined: Fri Jun 20, 2014 4:43 pm
Location: Cornwall UK
Contact:

Re: Traction tyres - pointless??

Postby Emettman » Fri Jan 02, 2015 2:47 pm

Sc0tty wrote:Guys,

Do real life engine have traction tyres?? I thought tractive force was all to do with mass vs aerodynamic drag etc..


Trouble is, a few things go wrong when you make a scale model of a locomotive.

At half size the loco is half the length, A quarter of the area and one-eighth of the volume.
The weight is going down far faster than the size, and this has a distinct effect on proportionate traction of the driving wheels.

The effect on strength is an interesting one. Mainly linked in a beam to cross-sectional area, a model will appear to be better off as it gets smaller as it's weight reduces by 8 every time the area reduces by 4, but the forces on moving parts can be another matter.

Adding weight to a model loco will help with traction, providing it is not going over what the motor and wheel bearings can handle.
More is not always better.
Compared to a relatively light loco with traction tyres, one without traction tyres but more weight and a stronger motor and stronger axle bearing set could well be significantly more expensive to manufacture.
(And to sell to a mass market. A fair proportion of which wants locos to pull up unrealistic gradients and impossibly sharp curves!)

Chris
"It's his madness that keeps him sane."

Dad-1
Posts: 5613
Joined: Sun Aug 24, 2008 8:05 pm
Location: Dorset - A mile from West Bay.

Re: Traction tyres - pointless??

Postby Dad-1 » Fri Jan 02, 2015 4:30 pm

I wouldn't want to run my 14XX's without traction tyres as haulage would become too limited.
The same goes for my Hornby Caledonian single. It would be better not to have them as all
steel wheels allow more effective pick-up, but I want to have trains behind my locomotives
rather than something that looks fine but can't pull anything.

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

Bigmet
Posts: 6466
Joined: Tue Aug 14, 2007 2:19 pm

Re: Traction tyres - pointless??

Postby Bigmet » Fri Jan 02, 2015 5:05 pm

It is always possible to do without traction tyres if the mechanism design is good. This may cost a little more than the simple work-around of traction tyres, but brings two great advantages. Because the driven wheels are where most of the model's weight should bear, and the drive confers some measure of self cleaning, pick up is optimised. What is eliminated is the unreliable (apt to stretch or crumble) dirt generating and often derailment provoking rubber tyre.

Front coupled machines like the 14xx 0-4-2T and M7 0-4-4T are among the most problematic in model form; because there is little bodywork volume over the leading coupled wheel, and a large rear overhang, so that the model tends to seesaw on the trailing coupled axle. The M7 has at the moment much the more recent model, and while the design of the mechanism is not all it could be*, it will significantly outperform the 14xx. Hopefully the O2 0-4-4T from Kernow/DJM and 14xx from Hattons/DJM will show furthe advance in design by better materials choice and placement of light components in the rear of the loco.

*Hornby's main mistake on the M7 is to have the light weight and bulky decoder socket in the smokebox over the leading coupled wheel. Thats the place for the densest metal possible, ideally tungsten. The socket can go somewhere rearward of the coupled wheels where there is more space.

User avatar
Bufferstop
Posts: 11039
Joined: Thu Mar 11, 2010 12:06 pm
Location: Bottom end of N. Warks line

Re: Traction tyres - pointless??

Postby Bufferstop » Fri Jan 02, 2015 6:44 pm

Traction tyres were almost unheard of in the days of diecast chassis, worm and gear drive, and open frame motor. In Hornby Dublo's case you also could add the diecast body. Roll on Triang's pancake (Ŕingfield) motor with low ratio spur gears, available torque at lower speeds was poor. Long trains and or toy train gradients could only be tackled with the aid of rubber. I banished the rubber by swapping wheels on ringfield bogies, I also rewheeled my 0-4-2 by canibalising an older chassis. Careful driving and clean track keep wheelslip to a minimum. In the case of the 0-4-2 wheelslip is fairly prototypical, those prominent sand hoppers weren't there for decoration. My collection of homebuilt 0-4-0s pull loads which would have taxed the prototypes, using Hornby type 7 motors and 40:1 gearsets. I haven't ventured into double reduction gear drives, yet. I need to improve my construction techniques first.
Growing old, can't avoid it. Growing up, forget it!
My Layout, My Workbench Blog and My Opinions

User avatar
Emettman
Posts: 2353
Joined: Fri Jun 20, 2014 4:43 pm
Location: Cornwall UK
Contact:

Re: Traction tyres - pointless??

Postby Emettman » Fri Jan 02, 2015 7:24 pm

Bigmet wrote: Thats the place for the densest metal possible, ideally tungsten. The socket can go somewhere rearward of the coupled wheels where there is more space.


Not holding out for depleted uranium?
I suppose it could be hazardous in the event of a major head-on collision.

Chris
"It's his madness that keeps him sane."

b308
Posts: 4829
Joined: Sat Apr 15, 2006 5:48 pm
Location: North Worcs

Re: Traction tyres - pointless??

Postby b308 » Fri Jan 02, 2015 8:22 pm

Sc0tty wrote:Do real life engine have traction tyres??


Not that I know of!

GWR_fan
Posts: 4945
Joined: Sun Apr 29, 2012 11:57 pm
Location: Antipodes

Re: Traction tyres - pointless??

Postby GWR_fan » Fri Jan 02, 2015 8:23 pm

Depleted uranium was used by the aircraft engine manufacturers and mounted to the nose cowl structure to balance out any harmonics imbalance. Large wide body commercial aircraft used a lot of depleted uranium and the only maintenance proviso was to ensure the outer coating was kept intact when handling. They were quite inert. Given that many aircraft parts were cadmium plated, depleted uranium was the least of your problems.

GWR_fan
Posts: 4945
Joined: Sun Apr 29, 2012 11:57 pm
Location: Antipodes

Re: Traction tyres - pointless??

Postby GWR_fan » Fri Jan 02, 2015 8:24 pm

b308 wrote:
Sc0tty wrote:Do real life engine have traction tyres??


Not that I know of!


I cannot recall if the Paris Metro or London Underground but the carriages ran on rubber tyres for quietness (and presumably traction).

b308
Posts: 4829
Joined: Sat Apr 15, 2006 5:48 pm
Location: North Worcs

Re: Traction tyres - pointless??

Postby b308 » Fri Jan 02, 2015 8:47 pm

Paris Metro does, I don't think any of the LUR does... I assumed the OP was talking Mainline Railways and I don't know of any that do have them.

http://en.wikipedia.org/wiki/Rubber-tyred_metro

User avatar
Bufferstop
Posts: 11039
Joined: Thu Mar 11, 2010 12:06 pm
Location: Bottom end of N. Warks line

Re: Traction tyres - pointless??

Postby Bufferstop » Fri Jan 02, 2015 8:52 pm

Early French railcars "Michelins" ran on multiple rubber tyred flanged wheels, a design feature that returned to France with the ones tried in the UK. The Paris metro has some lines which have rail guided pnuematic tyred bogies. The people mover which shuttles between terminals at Gatwick is a similar design. I'didn't stop to look at the one that carries you beneath the runway between the two parts of T5 at Heathrow, from the noises it could well have been running on rubber. Airports are my least favourite places, I'm out of there as fast as my feet will carry me and the queues at the border permit.
Growing old, can't avoid it. Growing up, forget it!
My Layout, My Workbench Blog and My Opinions

User avatar
luckymucklebackit
Posts: 3240
Joined: Mon Jul 18, 2011 7:05 am
Location: Eaglesham, south of Glasgow
Contact:

Re: Traction tyres - pointless??

Postby luckymucklebackit » Fri Jan 02, 2015 9:17 pm

The class 86/3 sub-class were fitted with SAB resilient wheels - a wheel in two sections separated by a rubber bearing. Description here
http://www.traintesting.com/flexicoil_suspension.htm

On the model front - surely some inventive soul could come up with a replacement traction tyre made of a substance which maintains the required coefficient of friction without the nasty side effect of depositing loads of gunge on the track!!

Jim
This Signature Left Intentionally Blank, but since I have written this and I intended to do it, this Signature is intentionally not blank. Paradox or What?
My layout - Gateside and Northbridge
Image


Return to “Hornby - including Lima, Rivarossi, Jouef, Electrotren”

Who is online

Users browsing this forum: Google Adsense [Bot] and 7 guests