Prototype Wheels for DMUs

Dog Star

Western Thunderer
I guess that most of us reckon that we are savvy about the diameter and spokes of wagon wheels... and probably OK with details of coach wheels... and are au-fait with details of the driving wheels for our favourite engines. Fine... or so I thought. I now realise that all of the preceeding knowledge comes to naught when faced with First Generation Diesel Multiple Units - those "Heritage" units which are to be found on many preservation railways.

So first question... what is the nominal tread diameter of the wheels for powered and non-powered bogies? If it helps, I am interested particularly in wheels for the Derby Class 108.

Next question... there are 3-hole disc wagon wheels and 2 (or 4) hole disc carriage wheels... how many holes in wheels for DMUs? Again, interested specifically in Cl.108.

regards, Graham
 

Muddysblues

Western Thunderer
Good evening @Dog Star Graham, in general the DMU wheel diameters are 3' 1", and of a disc type design, with two holes in them I think, and this was the case for the Derby built Class 108 DMU.

I am prepared to stand corrected on the number of holes per wheel though.

Hope this helps
Craig.
 
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DougT

Western Thunderer
Graham

Try as I might, I cannot find the reference I read recently to 1st Gen DMU’s having wheels with a 3ft0 diameter so I revert to my understanding that the wheels were 3ft1.

Interestingly, this diagram book extract (from Barrowmore MRG archives) shows the axle centres at 1ft7 which equates to a 3ft2 diameter wheel but I think that includes flange depth. I don’t believe that there is any difference in wheel size between driving and non-driving bogies.

7BA5A49F-C19C-49C3-B3FB-26AB976CE7E0.jpeg

Doug
 

Muddysblues

Western Thunderer
Ha ha .... I noticed the OP date after my reply :)), but I thought, what the heck, leave the info up there anyway, it may stop the question being asked again, and save that person waiting another 7 years :D, to wait for a reply.

Best regards
Craig
 
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