Wheel Diameter Sizes ?

[HST-DAVE]

Hi

Does anyone know what is the smallest wheel diameter* used on standard gauge locos and/or current rolling stock? (*not including flange diameter)

Curious to know as I'm looking into wheel design this week for our hydrogen train research... Thanks...
Dave

 

[142094]

I would expect that the Voyager wheels would be one of the smallest, although I don't have the exact diamater.

 

[HST-DAVE]

Thanks, a quick search says they use B5005 bogies, they certainly look smaller. I shall see what I can find out... cheers, Dave

 

[ainsworth74]

Worth baring in mind that the B5005 is only used on Class 220 Voyagers. The Class 221 Super Voyagers use Y36 bogies.

 

[TGV]

This has been discussed before - the voyager wheels aren't as small as you think - the design of the bogie frame makes it look much smaller. It is smaller than the Y36 wheels, but they're still larger than some wheels used on 9'6" container wagons.

 

[HST-DAVE]

Thanks, container wagons seem to be winning at the moment by the sounds of it...
Dave

 

[jopsuk]

Tram wheels? London Underground deep tube stock? Both are standard gauge in this country

 

[HST-DAVE]

'Tram wheels' is interesting, would never of thought of that one, will check them out! thanks.., Dave

 

[WatcherZero]

For Light Rail those that I could find
Name New/worn
Docklands 760mm/660mm
T68/T69 740mm/???
Sheffield Supertram 670mm/590mm
M5000 660mm/580mm
Incentro AT6/5 660mm/580mm
CR4000 630mm/550mm
Flexity 2 Blackpool 600mm/540mm

Quite a range of sizes.

 

[HST-DAVE]

Thanks WZ, that answers my question. We can fit 600mm into the design. The hydrogen train is less than 50% in mass (weight) than conventional trains and has a very low centre of gravity. Smaller wheels may mean that they will wear down quicker but hopefully this will be balanced by the reduced loading. We are also looking into using very high carbon steel for the wheels.
cheers, Dave

 

[Peter Mugridge]

Are there any drawbacks with smaller wheels that need to be considered? I am thinking in terms of heat dissipation from braking, for example.

 

[jopsuk]

Bearings. Small wheels rotate more often for the same distance travelled, putting a lot more stress on the bearings- they got hotter easier.

Intrigued by the 50% weight savings claim- I assume much greater use of composite materials in the structure than present trains? one of the interesting bits with rail though is that weight, at least in the right place, isn't all bad- more weight does increase the amunt of energy needed to accelerate, but it also improves the adhesion of the drive/brake wheels- too little weight may (but doesn't have to, with careful design) lead to wheel slip when accelerating and skidding along (causing flat spots) when attempting to stop!

 

[HST-DAVE]

Good points, we should be ok with the bearings and we use 'traction control' on the motors for acceleration. We haven't worked out the braking yet . Needs to go from 260mph max to 0. Some form of regenerative braking is to be incorporated. Maybe an ABS can be included, a question for next week to solve I think...
cheers
Dave

 

[DarloRich]

Hi

Does anyone know what is the smallest wheel diameter* used on standard gauge locos and/or current rolling stock? (*not including flange diameter)

Curious to know as I'm looking into wheel design this week for our hydrogen train research... Thanks...
Dave

do you mean size when fitted new or minimum permitted size in traffic (after turning etc?)

 

[Hydro]

Have a butchers at Freightliners FLA wagons. The wheels are tiny.

http://www.freightliner.co.uk/default.aspx?PageID=141

 

[Kingfisher200262]

Good points, we should be ok with the bearings and we use 'traction control' on the motors for acceleration. We haven't worked out the braking yet . Needs to go from 260mph max to 0. Some form of regenerative braking is to be incorporated. Maybe an ABS can be included, a question for next week to solve I think...
cheers
Dave

If you don't incorporate WSP (wheel slip-slide protection - the railway equivalent of ABS) into your design, you'll have wheels shaped like thrupenny bits in no time (OK, so I'm showing my age!).

Remember this is metal on metal and the coefficient of friction is very low.

 

[Peter Mugridge]

Could one not save weight on larger wheels by using holes in them similar to the Bulleid boxpok type wheels? ( Holes, not spokes, for stress reasons )

 

[HST-DAVE]

WSP sounds crucial. We are just working on the weights and forces at the moment.

We're having to design top down, which is probably a bit unusual, the brakes are the last piece. This is because we have had to work around the power system which is fixed in size and weight.

Maybe we can have a composite material on the wheels that is just slightly softer than the steel rails? Don't know if this has been tried before? ... Dave

 

[WatcherZero]

Rubber tired trams run in France and elsewhere under that theory (main location close to Michelin HQ :roll, theoretically theirs much less wear on the rails as they just guide the vehicle while the weight is on the rubber tires which are cheaper to replace. In practise you go through a lot of tires and you get rutting of the road tarmac where they run over the same spot continuously meaning more road repairs and problems to other traffic.

 

[HST-DAVE]

The french metro used to have rubber tyres too. I think rubber will be far too soft for what we would be looking at; rail contact area is small and would wear down very quickly. Thinking more of a carbon composite...

 

[WatcherZero]

I wasnt suggesting using it on rail, just sharing an anaecdote.

 

[HST-DAVE]

Thanks WZ, knew what you meant about the rubber tyres. We're now looking at tram size wheels based on your earlier suggestion, so thanks again for that.
Our train is actually much much lighter than I thought possible on todays latest calculations, looking at between 25-30% of normal weight, fully built , compared with say a Voyager set of similar length..
Just need to design wheels and brakes Dave

 

[cyclebytrain]

Carbon would be a no go for that sort of thing. Aramid perhaps.

 

[HST-DAVE]

Aramid maybe.. I've passed this on to our researcher who is going to consult with a few composite Cos.
Next 2 questions :-
Are rail tracks magnetic, i.e. is a magnetic force attracted to them?
and..
We based the original conceptual train design on a platform height of 1.1m above top of rail, is this correct? Is there a UK standard?
Thanks in advance...
Dave

 

[WatcherZero]

Official uk standard is 915mm with a margin of 25mm, however with the age of many stations built pre nationalisation by different private companies to different standards it varys quite wildly from about 800mm to 1200mm depending on the rail line. High speed rail follows European standard of 550mm or 760mm (HS1 is 760mm).

Low floor trams are about 320 (Midlands, Croydon, Blackpool) - 420mm (Sheffield)

 

[HST-DAVE]

That's very interesting, we had 1.1m and had to step down into train, 915mm or lower would be ideal for the present design.. 550mm seems incredibly low but is more in line with our floor level. We'll have to go for 915mm I think as it is expected to be a suburban/rural train.
Dave

P.S. Tram at 320mm? I think we've accidentally designed a very very high speed tram that runs on railtrack. Our floor level is at 340mm, perhaps we can suggest demolishing all the station platforms in rural areas

 

[Kingfisher200262]

Aramid maybe.. I've passed this on to our researcher who is going to consult with a few composite Cos.
Next 2 questions :-
Are rail tracks magnetic, i.e. is a magnetic force attracted to them?
and..
We based the original conceptual train design on a platform height of 1.1m above top of rail, is this correct? Is there a UK standard?
Thanks in advance...
Dave

Rail is steel, so magnets (either permanent or electro-magnets) stick to them. Some trams and light rail vehicles use magnetic track brakes in addition to friction and electric brakes.
--- old post above --- --- new post below ---

Official uk standard is 915mm with a margin of 25mm, however with the age of many stations built pre nationalisation by different private companies to different standards it varys quite wildly from about 800mm to 1200mm depending on the rail line. High speed rail follows European standard of 550mm or 760mm (HS1 is 760mm).

Low floor trams are about 320 (Midlands, Croydon, Blackpool) - 420mm (Sheffield)

The Crossrail rolling stock specification calls up platforms at 1100 mm above rail level for the new stations.
--- old post above --- --- new post below ---

Thanks WZ, knew what you meant about the rubber tyres. We're now looking at tram size wheels based on your earlier suggestion, so thanks again for that.
Our train is actually much much lighter than I thought possible on todays latest calculations, looking at between 25-30% of normal weight, fully built , compared with say a Voyager set of similar length..
Just need to design wheels and brakes Dave

If the vehicles are too light, you won't get sufficient adhesion for good acceleration and the stability of the train, particularly in strong cross-winds will be poor.

 

[Ploughman]

Rail is steel, so magnets (either permanent or electro-magnets) stick to them. Some trams and light rail vehicles use magnetic track brakes in addition to friction and electric brakes.

Don't forget that some OHL equipment on rolling stock is actuated by sleeper mounted magnets.
Also AWS magnets are just what they say.
Just in case this may have an effect on your project.

The 915mm height is actually 915 + 0 / - 25mm
Horizontal is taken as 730mm Running edge to face of platform.
Further complicated by the HMRI stepping distance from stock floor level to Platform surface.

 

[HST-DAVE]

It's light but low profile. We have surplus kW power available so was thinking maybe electro-magnetic attraction to rails can be used in acceleration and braking..
Thanks for confirming that this has been used; in your mail Kingfisher, it is very helpful, and it looks like that is where the original 1100mm figure came from.
We've been concentrating on the hydrogen technology for 2.5 years now, these questions may seem easy 4 you folks but we have a steep learning curve now when it comes to making it work on existing track.. thanks all .. Dave
--- old post above --- --- new post below ---
AWS and OHL .. will need to look into this too. Hopefully the electro-magnet field will be drawn to rail and not zap the systems on the sleepers..

 

[Kingfisher200262]

It's light but low profile. We have surplus kW power available so was thinking maybe electro-magnetic attraction to rails can be used in acceleration and braking..
Thanks for confirming that this has been used; in your mail Kingfisher, it is very helpful, and it looks like that is where the original 1100mm figure came from.
We've been concentrating on the hydrogen technology for 2.5 years now, these questions may seem easy 4 you folks but we have a steep learning curve now when it comes to making it work on existing track.. thanks all .. Dave
--- old post above --- --- new post below ---
AWS and OHL .. will need to look into this too. Hopefully the electro-magnet field will be drawn to rail and not zap the systems on the sleepers..

I suggest that you refer to the plethora of standards that your train MUST comply with before spending too much time, effort and money on research & development. I good place to start is the Railway Group Standards, which you can access online here. If you're going to even think about using magnetic fields to help adhesion, you'll need to think very carefully about electro-magnetic compatibility, both in terms of conducted and induced emissions and also immunity, as many railway systems are susceptible to magnetic fields, including some signalling systems. The relevant standard for EMC is BS EN 50121. Here's a useful source of info.