Gibson v Romford/ Markit wheel back to back settings

Hayfield

Member
Location
Essex
Whilst not quite track related I am building a loco chassis in EM gauge using Romford wheels initially, then reverting to Alan Gibson wheels, is my memory playing tricks or am I getting things mixed up. are they both 16.5mm back to back or are Gibson's 0.1mm wider please

Reason being is that I am building detachable brake gear and Gibson wheels are thinner

Thanks
 
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Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
@Hayfield

Hi John,

For standard EM:

RTR wheels: 16.4mm back-to-back MAX.

Romford/Markits wheels: 16.5mm back-to-back MAX.

Kit wheels (Alan Gibson, Ultrascale): 16.6mm back-to-back MAX.

For all of them: 16.3mm back-to-back MIN.

So for Alan Gibson wheels, 16.5mm or 16.6mm will work. However, for the best running, always get as close to the MAX as possible without exceeding it. So aim for 16.6mm.

cheers,

Martin.
 
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Hi John,
Romford/Markits wheel back-to-backs are set by the distance between the shoulders on the axles although never having used them for EM I don't know what that dimension is set to when the axle is made. What do your axles measure over the shoulders ?

Rob
 
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Hayfield

Member
Location
Essex
i have a cheap set of callipers, the axles read 16 mm

Like many I find Romford/Markit wheels easy to fit, but in the past I have struggled with Gibson's. I now have a G W Models wheel press, plus the loco I am building needs 4' 10" wheels. The other thing is, in my opinion Gibson's do look better
 
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Hi John,
What back to back do the Romford wheels measure when mounted on the axle ? The raised boss on the back of the wheels will add to the length of the 16mm axle length. You really need to have a decent calliper or a back to back gauge set to your intended measurement.

The GW press will help with the Gibson wheels provided you take it steady. The main issue I have seen is when you remove wheels from the axle to paint the chassis or fit brake gear etc - they often don't go back on just right.

Rob
 
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Hayfield

Member
Location
Essex
Romford seem to have 16.5 mm back to back.

This is partially my issue, I am using Romford wheels to build and test the chassis, when everything is tested, working and painted I will then fit the Gibson's

Its further complicated in the fact I wish to make the brake gear detachable, I am going to use a length of thin micro bore tube through the chassis and I need to know how long to make them, as they will go through the frames and soldered in place (where necessary the centre part will be cut out to fit the motor) I need to align the brake gear to fit Gibson wheels not Romford

with respect to my first post, I have checked the size of Gibson EM back to back gauges and they are 16.5 mm, I think certainly initially I will have to go with this
 
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Phil O

Member
Location
Plymouth.
Hi John,

I think that you will be hard pressed to work to a tolerance of 0.1mm unless working with a micrometer, as long as the brake shoes are clear of the flanges there should be enough meat on the tread to accommodate the shoe, the real thing is fairly slack.
 
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