A collection of stupid questions...

[jbartus]

Hi all,

Re: Topic title, It's what I imagine you'll all be saying once you see the whoppers I have for you, but what can I say I never worried about it with my HO scale models (if the cars coupled then I was happy, and wheels were wheels (unless they were plastic, then they were trash)) so on to the questions:

If my wheel for the car I am making is 36 inches, is that the diameter to the tread? Outer edge of flange? Somewhere else? I looked around and I found some confusing info about the 36 inches somehow involving a groove nowhere near the edge of the wheel (several inches in from what I could tell) that somehow in some way helped with accident diagnosis... not very helpful for my modeling.

The second question is... research indicates couplers are supposed to be @ 32.5-34.5 inches above the <unspecified source>(Rail? Sleepers? Roadbed? Moon?). Is that measuring from the top, bottom, or center of the coupler and further, where is that measured from?

Any help you can provide is most appreciated. Thanks!

 

[fran1]

stupid answer 1- tyre size is usually the diameter of the rim, so a 17" tyre means where it fits the rim not overall diameter, getting sillier the tyre diameter top-bottom depends on the profile of the tyre.
stupid answer 2- I'll go for top of rail to centre of coupler.

 

[jbartus]

stupid answer 1- tyre size is usually the diameter of the rim, so a 17" tyre means where it fits the rim not overall diameter, getting sillier the tyre diameter top-bottom depends on the profile of the tyre.
stupid answer 2- I'll go for top of rail to centre of coupler.

You've lost me... I recognize that tyre is En-UK for tire but I was asking about trains not cars :S
Thanks for your answer on the second

 

[clam1952]

This may help clarify the answer to 1 http://en.wikipedia.org/wiki/Railway_tires.

 

[jbartus]

This may help clarify the answer to 1 http://en.wikipedia.org/wiki/Railway_tires.

Oh okay, I kind've remember reading somewhere many years ago about steam engines having "tires" -- the wikipedia article didn't make it clear to me though, do modern wheels have these "tires"? If not, is the measurement to the contact surface that rides on top of the rail or elsewhere? How big is your average wheel flange? Any idea on thickness? What's the meaning of life?

I know, I know, all stupid common sense stuff I'm sure

 

[PerRock]

Almost all height dimensions for railroads start from the top of the Rail.

peter

 

[jbartus]

Almost all height dimensions for railroads start from the top of the Rail.

peter

Thanks Peter

Now I just need the wheel question settled and I'll be in good shape xD

P.S. - Your signature doesn't link to the forum, has some other URL that ends in a 404.

Jon

 

[kws4000]

Thanks Peter

Now I just need the wheel question settled and I'll be in good shape xD

P.S. - Your signature doesn't link to the forum, has some other URL that ends in a 404.

Jon

Locomotive tires are typically tapered, and I reckon the wheel diameter is measured either at the edge or halfway btwn edge and flange, NOT at the flange, as it does not support any load.
The loco tire taper is for going around curves. Don't ask now, I'm in college right now.

 

[tbryson2]

This does bring up an interesting question. I just saw a video which clarified that the "tire" is fastened onto the "wheel" of the engine. I believe I understand jbartus' question, and he did not ask about the "tire".

(if I understand it correctly), Question was, is the diameter of the WHEEL what we use to create the (entire) wheel, or should we add the tire to that also for the diameter? (which would make the overall "wheel" bigger in diameter)

i.e. When plans refer to a steam engines "wheel" and states that it is 55 inches, does that include the tire also? (I do realize that for "trainz" this it pretty irrelevant. Just curious.)

 

[clam1952]

I presume this is what was confusing you? - Measuring Locomotive Wheel Diameters http://www.geocities.ws/lokomac8/wheeldia.htm

 

[jbartus]

I presume this is what was confusing you? - Measuring Locomotive Wheel Diameters http://www.geocities.ws/lokomac8/wheeldia.htm

Actually, I think your link just cleared this up, anyone want to verify that I understand this correctly?

 

[narrowgauge]

That is misleading. The effective and important diameter of a rail wheel is the rolling diameter. From the centre of the wheel to the rail head x 2. While the dimensions referenced in that page are important in the real world they do not matter in Trainz apart from the appearance. The reference groove is designed to allow wheel wear to be determined without instruments.

Some one can correct me if I'm wrong but tread width is about 4.5" and width overall is about 5.5" Not like the 'pennies" on the orginal Trainz rolling stock.

Peter

 

[jbartus]

That is misleading. The effective and important diameter of a rail wheel is the rolling diameter. From the centre of the wheel to the rail head x 2. While the dimensions referenced in that page are important in the real world they do not matter in Trainz apart from the appearance. The reference groove is designed to allow wheel wear to be determined without instruments.

Some one can correct me if I'm wrong but tread width is about 4.5" and width overall is about 5.5" Not like the 'pennies" on the orginal Trainz rolling stock.

Peter

So.... the 36" is like I drew or at the tread? x_X

 

[wva-usa]

What you drew would be a 38 inch diameter wheel.

 

[jbartus]

What you drew would be a 38 inch diameter wheel.

So x=1"?

How about flange size?

Edit: How did you get the 38 inches? Doesn't match proportionally in the photo...

 

[wva-usa]

How do I get 38?

Per the dimensions shown on your drawing: 36 + 1 + 1 = 38 or 18 + 18 + 1 + 1 = 38.


Dimensions for American modern freight wheels.

 

[Dermmy]

Not quite! the dimensions in that picture are the wheel plus the rim plus the tyre, which would give about a 45" wheel!

The quoted diameter of a railway wheel is nominal, not exact, but the nominal 36" wheel is measured across the rolling diameter, shiny bit to shiny bit, plus maybe an inch on a brand new wheel. If you make the whole thing 36" across nobody will ever complain!

Flange size - about 10% of the size on most Trainz wheels will be about right. There is a pretty good drawing here. Most Trainz wheels seem to be modelled on particularly bad model railway wheels and have 'orribly over-sized flanges....

 

[wva-usa]

I've seen plenty of steam locomotive drivers that have tires, but I've never, ever seen a modern American freight wheels that has tires, but yes, they do have rims.

 

[jbartus]

How do I get 38?

Per the dimensions shown on your drawing: 36 + 1 + 1 = 38 or 18 + 18 + 1 + 1 = 38.


Dimensions for American modern freight wheels.

Where'd the 1's come from? Edit: I have this funny feeling in the back of my head you're reading my varible "x" as a "1"

You'd be my hero if you can produce such a table for passenger car wheels o_o

 

[narrowgauge]

I think you will find that cast driving wheels on steam engines whether cast steel, or at one time cast iron, will have tyres(tires) as they are too expensive to replace the entire wheel. The more recent smaller wheels are turned from a solid blank, they can refaced several times by turning or grinding, but when they wear beyond a certain point it is cheaper to fit a completely new wheel and axle set. The older type wheels would not support the current day axle loadings. It is possible that the worn wheels may be pressed off the axle and new wheels pressed on.

In relation to present day solid wheels, 'rim' and 'tread' mean much the same.

I believe that some more modern wheels may have reverted to shrunk on tyres where the tyre is made from a more expensive steel allowing the selection of steels better suited to the end use.

On a related subject, we all know that the wheel tread is coned (tapered) but do we know that modern rails have an inwards matching taper on the running face and the web also inclines inwards. I doubt whether any of the Trainz rails have this taper feature.

Peter