Aluminium centred wheels

[ilvaporista]

Does anyone have any experience or information on using aluminium wheel centres with steel tyres for spoked railway wheels? I have been asked the question by a friend here in Italy.

I have seen this a couple of times in America but nothing here in Europe. I did not find anything on the net. I've seen it on a 5" Shay and a battery electric loco.

As for differential expansion I am in two minds. I researched a problem many years ago on bearing retention in alternators. Radially in between the bearing and the housing was a plastic element with 3 enclosed lugs at 120 degrees which when warm expanded in radial slots acting like a three jaw chuck, tightly gripping and locating the bearing. At the start we were all convinced that differential expansion would lead to the bearing becoming slack. A lot of testing and investiagtion showed that the bearing was rigidly held and centralised.

I just wonder whether the same would happen with spoked wheels, although this might lead in the extreme to 'threppenny bit' (oops sorry 50p) shaped wheels. Though I think that the tensile stresses in a steel tyre would mostly even out the 'spoke effect' of point radial loads

Any comments, ideas or experience?

[alanstepney]

The question that springs to my mind, is Why?

Apart from that, long ago one guy did produce a locomotive with polygonal wheels.
The idea was that the flats would have far more grip than the point-contact of normal wheels.
Need I say that it didnt work?

[GWRdriver]

It is the opinion of many of us (over here) that the problem with steel tires on aluminum, and potentially even bronze, is that over time the softer metal will be compressed by the rolling action of the tire and axle so that eventually the tire (and/or axle) becomes loose. The problem would be come greater as locomotive weights and wheel loading rises. I can't recall ever actually seeing a locomotive with aluminum wheel centers.

By the way, did you know that once upon a time we all pronounced aluminum the same way? Then the British decided they would change the spelling to bring it into line with all the other new elements ending in "ium", . . . such as Unobtainium.

[havoc]

Good question and I'm also interested in the results.

I do not see a problem for the smaller scales like 0 and 1. But something else than dead soft pure Al should be used.

But for larger ride-on size? I don't think compression will be the problem. More creepage when the Al is too soft and the tire is crimped on or shrunk.

[joegib]

By the way, did you know that once upon a time we all pronounced aluminum the same way? Then the British decided they would change the spelling to bring it into line with all the other new elements ending in "ium"

According to the aluminium wiki it's a little more complicated than that:

en.wikipedia.org/wiki/Aluminium

Humphrey Davy, the discoverer of the element, first used ALUMIUM and then adopted ALUMINUM (1812). British general usage then quickly changed to ALUMINIUM. Webster's American dictionary used that spelling in 1828 and it appears to have been the form used there for most of the 19th century. American usage then changed to ALUMINUM but Webster's dictionary continued using the British form until at least 1913.

So, yes, both British and Americans used the same name for most of the 19th century but it was Americans who changed the settled usage.

Coming back to the main question, the obvious attraction of casting wheel centres in aluminium is that for the home foundry, this is potentially an easier process than casting iron. We're used to readily available iron wheel castings from the trade in this country. That's probably not true in Italy so MEs there need to be more resourceful.

[mutley]

What about electrolysis? Aluminium and steel are two of the worst metals for reacting together. A steam engine provides one of the worst enviroments going with plenty of both water vapour and heat.

Andy

[ilvaporista]

All very valid points and I thank you for the input. Yes the difficulty in getting castings here is one reason. Just think that whilst you might consider some suppliers prices as high we then have to add on the transport costs here to Italy. I am usually asked when I drive back to bring a few things over but the family got in a bit of a strop when we had to bring back a chassis of a 7 1/4" King. Making the kids share the car with than for 16 hours was probably not the best plan I ever made.

[circlip]

Wow thats the ultimate sinker Mutley, electrolytic corrosion, forgot about that little gem. Austin Healey 100/4 - 6 & 3000, AluminIUM wings with a steel centre section, constant white sludge forming at the bolted joint despite a plastic separator, Oh what fun.

[mutley]

A lot of high end modern cars are built with a steel chassis and aluminium bodywork, Audi's and Jaguar's for example. They all have a chemical barrier put between the diffrent parts though to stop the electrolysis happening. How your local dealer is to repair such a vehicle in the event of a major accident is another question
At a guess I reckon this proces may be some way out side the capability of most model Engineers workshops.

[Noddy]

mutley said:

A lot of high end modern cars are built with a steel chassis and aluminium bodywork, Audi's and Jaguar's for example. They all have a chemical barrier put between the diffrent parts though to stop the electrolysis happening. How your local dealer is to repair such a vehicle in the event of a major accident is another question
At a guess I reckon this proces may be some way out side the capability of most model Engineers workshops.

Happy memories of series three landrovers:

The steel chasis rusted out and snapped long before the body work went, although one old fellow's had a hole in the back of the cab, where his dog pissed on it every morning. the cab stank like an old tramp.

Sorry Adrian, not much help with your question, although I can't see anything wrong with the idea of Aluminium centres with steel tyres, if the centre is well anodized, and they are shrink fitted. For the weight bearing, I think we have scale working on our side for once.
Keith