Formula for working out drag on curves

[Greg Elmassian]

There were some wheels made by Accucraft for their AMS line with hugely conical profiles, whether it was to enhance the differential action of a larger diameter contact on curves, or to enhance the self centering ability on track, they were a phenomenal failure. They were removed from further production cars, but still sold to the market as replacement parts...

As everyone above has pointed out, there is a fine line between too much taper and not enough, and it can indeed be speed dependent.

Most people have come back to 2-3% taper, and a "reasonable" fillet between flange and tread, but with our unprototypically tight curves, there is no great solution other than having one or more wheels turn independently of the other.

Greg

 

[Rhinochugger]

There were some wheels made by Accucraft for their AMS line with hugely conical profiles, whether it was to enhance the differential action of a larger diameter contact on curves, or to enhance the self centering ability on track, they were a phenomenal failure. They were removed from further production cars, but still sold to the market as replacement parts...

As everyone above has pointed out, there is a fine line between too much taper and not enough, and it can indeed be speed dependent.

Most people have come back to 2-3% taper, and a "reasonable" fillet between flange and tread, but with our unprototypically tight curves, there is no great solution other than having one or more wheels turn independently of the other.

Greg

So you're back to your ballbearing wheelsets, and going to see the bank manager for a mortgage

 

[Greg Elmassian]

Exactly!

In my case I am somewhat lucky in that my rail is stainless steel, and somewhat slippery, and this helps with 50 foot and shorter cars.

Of course the downside is pulling on grades, I need multiple locos since the coefficient of friction is less. Longer cars can have other issues too.

Greg

 

[rusty spike]

Flip your stock over, and spin the axles by hand.. - You DO lubricate your axles, don't you?

You sometimes find a tight axle, or two.. These can make one heck of a difference.
Also, any bogies (trucks, US) that do not articulate freely? - All adds to drag..

PhilP.

Hi Philip,
The coaches are new, but I have removed the electrical pickups and added a drop of light oil to the axleboxes.It made a difference but not enough to allow the coaches to roll away on the incline. I may look at having some work done on the journals and axleboxes to allow ball bearings to be fitted. TBH apart from my brass long caboose, none of my Accucraft wagons run anywhere near as freely as my kit built 0 gauge stock.

 

[JimmyB]

None of my Accucraft wagons run anywhere near as freely as my kit built 0 gauge stock.

Most 0 gauge stock runs on pin point axles which is why they are freer than running in journals less friction.

 

[Rhinochugger]

Most 0 gauge stock runs on pin point axles which is why they are freer than running in journals less friction.

That was the question I was going to ask

 

[Paul M]

Just thinking aloud here so may be writing tosh, but if your axles are too free wheeling would that actually make things worse on a heavy train? Could there be the problem of the weight of the coaches pulling back the locomotive? Similar to putting the trains brakes on to stop the back drag on the main line.

 

[Paradise]

Extra friction will create more drag and a waste of energy.

 

[JimmyB]

Just thinking aloud here so may be writing tosh, but if your axles are too free wheeling would that actually make things worse on a heavy train? Could there be the problem of the weight of the coaches pulling back the locomotive? Similar to putting the trains brakes on to stop the back drag on the main line.

Not an expert, but I would think the obverse would be true

 

[Rhinochugger]

Friction can be such a drag

 

[Paradise]

Just thinking aloud here so may be writing tosh, but if your axles are too free wheeling would that actually make things worse on a heavy train? Could there be the problem of the weight of the coaches pulling back the locomotive? Similar to putting the trains brakes on to stop the back drag on the main line.

You're thoughts maybe referring to the 'inertia' of a heavy consist. Any momentum will also be effected by drag/friction.

 

[AustrianNG]

I have ball bearing wheelsets on some of my stock - at the time of purchase more than 12 years ago the price was reasonable.
My memory of the manufacturer is poor though - it was aguy in he USA i think and I didn't get stung for outrageous customs charges and daft postage. rates.

 

[rusty spike]

I have ball bearing wheelsets on some of my stock - at the time of purchase more than 12 years ago the price was reasonable.
My memory of the manufacturer is poor though - it was aguy in he USA i think and I didn't get stung for outrageous customs charges and daft postage. rates.

I have had a conversation with a chap in the US who will convert the bogies (trucks) but wanted the complete assemblies to be shipped which would have been cost prohibitive for me. Unfortunately I sold almost all of my workshop equipment last year so I can’t do the work myself :-(

 

[Rhinochugger]

I have ball bearing wheelsets on some of my stock - at the time of purchase more than 12 years ago the price was reasonable.
My memory of the manufacturer is poor though - it was aguy in he USA i think and I didn't get stung for outrageous customs charges and daft postage. rates.

Probably SanVal - and that would have been before the postage rates went silly

I think what put me off was that they weren't suitable for the Accucraft metal bogies - i.e. the ones that really need 'em

 

[JohnSol]

Regarding Independent Ball Bearing Wheels;
FWIW; Custom Model Products (CMP) brass coaches came equipped with ball bearing wheels.

 

[AustrianNG]

Probably SanVal - and that would have been before the postage rates went silly

I think what put me off was that they weren't suitable for the Accucraft metal bogies - i.e. the ones that really need 'em

Yeah - San Val - those are the ones.
Mine have been out on the rails for the last 12 years - still roll smoothly

 

[Software Tools]

has wheels that have a more pronounced slope (dunno the proper term)

The term is angle.

 

[Paradise]

Yeah - San Val - those are the ones.
Mine have been out on the rails for the last 12 years - still roll smoothly

For those not in the know. Al Kramer who is eBay seller 'ana.kramer' used to own San Val and still sells the wheels in ball bearing and plain versions.

Items for sale by ana.kramer | eBay

 

[Greg Elmassian]

The term is angle.

Nope, the correct term is taper for this industry....


Greg

 

[David1226]

As posted previously in the topic 'A Question - Metal Wheels'

At an early stage I standardised on Al Kramer's wheels, from the US, for the Claptowte Railway. As Paradise has said they are solid turned brass, which makes them very, very heavy. The weight gives a low centre of gravity and the inertia, once rolling, means that they will roll straight over most track imperfections. They are/were available in bright Nickel or dull blackened nickel finish, I opted for the bright ones which I then painted, They are very expensive but as all the Claptowte Railway vehicles were hand produced over a period of many years, the cost was spread over a long period. If you standardise on one wheel type, whichever you choose, coupling height will not be an issue as all wheels will be the same diameter.







David