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How do you measure wheels?

8K views 12 replies 11 participants last post by  Graham Plowman 
#1 ·
I have three carriages that need new wheels, (currently have plastic with a white stripe on the walls
). Where do you measure them? Wheel circumference or axle length?

The carriages were formally Annie and Clarabel but are now primed ready for a new livery.


 
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#3 ·
Thanks a lot there Tony. Diameter is what I meant! I never was any good at mathematical terms...F at GCSE.


That's great, the ones I have seen are 12.5mm with three holes in, which measures about right against the ones I have. The carriages are quite small.


 
G
#4 ·
Hi Ian

You need to know the diameter AND axle length. Standard is 26mm however its not always adhered too. The thing is dont always replace like for like as manufacturers will often use a stock wheel for ease, in this case their 3 hole wagon wheel. AFAIK no coaches ever ran with this type of wheel so if you are going to the effort to replace them you may as well use something more accurate. Having said that I am not sure Annie and clarabel are based on real coaches anyway.

HTH

Jim
 
#13 ·
Being European where 24.5mm is the standard, it is to be expected that Lima would use such a standard.

Unfortunately, other manufacturers have used 24.5mm axles - I have several different Bachmann TEA tankers and other modern bogie wagons which have different axle lengths - either 26 or 24.5. It really depends on which factory was employed and it isn't necessarily the same factory for each run - TEAs being an example.

I seem to recall that teh early Bachmann Bullied coaches have some weird arrangement where one end of the bogie takes an approximation to 26mm and the other end takes 24.5mm.

I think the Dapol 6 wheel tankers also originally had 24.5mm, The Hornby ones probably do, given their Lima origins ?

Talk to Ultrascale and they will tell you how many times manufacturers change axle sizes, both length and diameter, including within the same model and different releases of the same model!
 
#5 ·
Hi Ian,

The 12.5mm diameter wheels you need are those available in Hornby pack R8096.As Jim S-W points out 3-hole wheels are wagon wheels,so the plain discs would be more suitable.
Unfortunately the design of these models is a work of pure Hornby fiction,being based not on a real prototype,but to fit on the old Tri-ang era derived brake van underframe,complete with the overscale buffer height,so fitting 14mm diameter wheels [which would normally be more appropriate for a coach] would only raise the buffer height,adding to the inaccuracy...
 
#7 · (Edited by Moderator)
*** More to the point, the existing bearings may have worn and the older plastic in the existing bogie may also have shrunk. The axle lengths will be fine... The axles are made with high production rate gear and a repeat CNC lathe has the same sort of abilities to be accurate time after time anywhere in the world.

Pinpoint bearings are pinpoint bearings. You may need to deepen or clean up the bearing a little but please do NOT file them. This will guarantee faster wear and give less free running than a properly mated pinpoint axle and properly coned bearing. There is a proper tool available for this called the "truck tuner" thats available from Micro-mark in USA and probably from one or two UK specialists too.

I have found the Hornby wheel packs - which are made with lathe turned wheels and axles, to be of good value and quality all of the time - with Bachmanns a little less so if they happen to use the older style cast wheel centres with the short stub axles.

Very nice wheels will also come from Ultrascale, Branchlines or Markits for OO, but expect to pay "more than a little more" per axle.

regards

Richard
 
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