Diesel loco wheel diameters

Jeremy Good
Posts: 101
Joined: Fri Feb 19, 2010 10:36 pm

Diesel loco wheel diameters

Postby Jeremy Good » Mon Jan 04, 2016 9:42 pm

All

This may seem like an obvious question but...

Are wheel diameters on the prototype measured over the diameter of the flange or part of the tread?

Also how much wear would be acceptable on a wheel before it becomes unserviceable?

I'm having fun trying to get a couple of diesels to ride at the right height and the conversion wheels I have used seem too small despite the label on the packs telling me they are the right size!

Any guidance gratefully received...

Jeremy

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Noel
Posts: 1046
Joined: Wed Jun 23, 2010 1:04 pm

Re: Diesel loco wheel diameters

Postby Noel » Mon Jan 04, 2016 10:39 pm

Jeremy Good wrote:Are wheel diameters on the prototype measured over the diameter of the flange or part of the tread?


Measurement is the diameter across the tread [I think at the mid-point thereof because of the coning, but no doubt someone will confirm this or correct me].

Jeremy Good wrote:Also how much wear would be acceptable on a wheel before it becomes unserviceable?


Historically most wheels had tyres [around 3" deep]; once wear exceeded defined limits, the tyre was reprofiled [some major BR diesel sheds had machines that could do this without removing the wheelset from the loco]. How many times the tyre could be reprofiled would depend on how long it took to arrive at the permitted minimum depth. Tyres could be replaced at this stage if desired. Modern wheels may be monobloc castings; I dont know whether these can be reprofiled.

Noel
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Noel

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grovenor-2685
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Re: Diesel loco wheel diameters

Postby grovenor-2685 » Mon Jan 04, 2016 10:58 pm

Noel wrote:Measurement is the diameter across the tread [I think at the mid-point thereof because of the coning, but no doubt someone will confirm this or correct me.

Confirmed
Historically most wheels had tyres [around 3" deep]; once wear exceeded defined limits, the tyre was reprofiled [some major BR diesel sheds had machines that could do this without removing the wheelset from the loco]. How many times the tyre could be reprofiled would depend on how long it took to arrive at the permitted minimum depth. Tyres could be replaced at this stage if desired. Modern wheels may be monobloc castings; I dont know whether these can be reprofiled.

Maintenance depots still have wheel lathes, monobloc castings can be reprofiled down to their wear limits but not usually retyred. Although some types of monoblock wheel can, after reaching the wear limit, have the tread and flange turned off to make a blank for retyring, I think this was more common with wagon wheels than diesels. Wear limits are mostly around 65 - 70mm off the diameter, you need the maintenance manuals to get an accurate figure.
Regards

Jeremy Good
Posts: 101
Joined: Fri Feb 19, 2010 10:36 pm

Re: Diesel loco wheel diameters

Postby Jeremy Good » Tue Jan 05, 2016 9:25 am

Keith and Noel,

Thanks for your responses and comments.

I'll have a look again at the wheel measurements later to assess what the best ones to use for various conversions - it looks like I should ignore the manufacturers "stated" sizing and measure the diameters.

Jeremy


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