Retyring

Looking at various societies web sites & youtube videos- when retyring wheelsets I notice that it seems to be S O P in the UK to take a small clean up cut off the wheel centers. From my extremely limited experience, this was not par for the course here in Australia or the USA unless there was some damage to the wheel centres such as a slipped tyre etc.

Can anyone advise if this is a normal practice and if so why? I would have thought that provided no damage had occured, the wheel centres would be fine as is.


Ian

 

I don't understand why, either, but it seems to be the trend with some suppliers. The last lot of tyres I had done (by Bagguley Engineering) certainly weren't, though.

 

This may be done because after service & old tyre removal the wheel centre may no longer be round. This is caused by the shape of a steam loco wheel to allow for a crankpin which may cause different stresses around the wheel circumference. Clearly for accurate measurement of the old centre & new tyre to the tolerances required for fitting roundness is essential.

 

Am i right in thinking that a wheel size ie 6ft 2 inches is the diameter of the wheel without tyres on, and with new tyres the diameter could be another 5-6 inches (including Flange)....

 

The diameter quoted in books and diagrams of a loco wheel is the diameter across the tread of the wheel (ie wheel centre section plus tyre) and is what is used to calculate the nominal tractive effort.

 

It was the practice in the BRML Eastleigh Works Wheel shop on all tyred wheelsets, including coach wheels. The slang term was "Topping" them.

 

The variation in wheel diameter due to tyres being turned can have quite an effect on a locos drawbar pull as can the variation in cylinder size as they are bored out to rectify wear. A black 5 with tyres at minimum diameter and cylinders bored out to the maximum is about 10% stronger than a Black 5 that is to design spec.

 

So its the rail to centre of axle x 2... and the flange typically another inch... ?

 

Don't include the flange.

 

errrrrrr..... ok.