Passenger Riding Trucks

[kelvin]

My club has a set of passenger riding trucks. The track is 5 inch gauge, raised and the trucks are bogie vehicles.  There have been a number of derailments and investigation reveals this has been going on for some time. The design of the bogies is, to me, unusual. ( I'm a new member and come from a standard gauge background ). There is next to no springing or allowance for deviations in rail level  and the bogies have fixed  axles  with each wheel having a roller bearing so these run independently rather than as a fixed wheelset  ie two wheels and one axle.  The tyre profiles are flat, which I'm told is usual 5 inch practice but I am of the opinion that the axle design may have some influence on the propensity of these vehicles to derail.  The track is on a sound formation and is in good order.

Any thoughts on this design of wheelset?

[andyhigham]

I'm not sure about the individual bearings
The lack of coning will be a factor, a coned wheel set will track centrally without flanges

[don9f]

An interesting question and on our 5” gauge raised track railway, many of the riding car wheel treads have no coning angle (ie “flat”) as you describe, but the bogies are either Reeves design or copies of this, with conventional wheelsets, only secondary suspension between the bogie bolsters and the car underframe, but there is some degree of accommodation of track twists etc, with self aligning double row ball bearing axleboxes. The two bogie sideframes are not tied together and can thus move a bit relative to each other. Derailments are rare.

I realise that so far this doesn’t help you much but derailments are most likely due to wheel unloading combined with high friction between wheel flanges and the inside (gauge face) of the rails. This can be aggravated by many factors, such as track twist, whether the rails are steel or aluminium, the wear of the rail gauge face, wear of the wheel flanges, diameter of the wheels (smaller wheels = higher risk) and so on.

I personally don’t think the idea of wheels spinning independently of each other on their axle is a good one, but if on a conventional wheelset the treads have no coning angle, they can’t self-steer anyway, so maybe my misgivings are unfounded. During my BR days, I was often involved in recovering vehicles with seized axles on a “wheel skate” and their wheels were very small and could spin independently, so severe speed restrictions were imposed, especially through pointwork, partly because of this.

Do the problems occur in the same place, the same car(s), the same bogie(s)? Lots of things to consider!

Cheers Don

[stevep]

I definitely think the wheels should be coned. As Andy says, they will centralise then, and the flanges won't run into the rails.

Also, have the flanges got a good root radius? Sharp corners are a factor in derailments.

[don9f]

I agree absolutely with wheels being coned but if the wheels are free to spin independently on the “fixed” axles (if I’ve read the original post correctly), then the wheelsets still won’t centralise (or self steer). Maybe the particular bogie design would be ok for riding cars just running up and down a straight track but are not particularly suited to curved track, especially if it has tight radii?

I read somewhere a long time ago in this forum about whether wheels should be coned or not / ground level v raised track etc. and again in the original post it says “The tyre profiles are flat, which I’m told is usual 5” practice”, but I personally don’t think that statement is necessarily correct.
It might have been way back but the standards these days recommend otherwise.

I await with interest for more info....

Cheers Don

[Midland]

Kelvin, you do not show from where you are but if you are in the southern half of the country, come and see ours. They do not derail so might be a good place to start!
David

[jackrae]

Many, many years ago I had exactly the same argument with our club president (cum self appointed chief engineer)
He had made sets of bogies with free wheels on fixed axles with some degree of coning. Derailments although not common, did occur too often.
I pursued the issue of the free-wheel-fixed-axle design with him and to demonstrate my case I made up a single axle to which were fixed a pair of coned wheels.
Our track was a 660feet oval and to demonstrate the effectiveness of my argument I literally threw the wheels down the track. A few moments later the axle set arrived back at where we stood, having successfully travelled the full circuit. I think I had made my point.

[coniston]

I agree with Midland, the Southampton passenger trolleys were designed by Bill Perret in the 60's and written up in ME some 25 years later, they are sturdy and very reliable with disc braking on all axels. They must be 50 years old now and still going strong. Have a look in ME for 'Bill Perret' 'Passenger comfort' you should find the articles.

[terrier060]

I think you will find the article by typing 'Bill Perrett Passenger Comfort' into Google. I has been published as a pdf but is copyright so not sure of the legal situation:

I agree with coniston. I believe some slight modification was done to allow the trucks to run on other ME tracks that had different guard rails to prevent the trolleys tipping if the passengers lent over too far.

Ed

[jackrae]

Here's a link to the article www.model-engineer.co.uk/sites/7/documents/passenger%20car.pdf
It's in the public domain so as long as you're not selling it as your own work or manufacturing and selling passenger trucks based on the article the word-police won't be bothered.

[doubletop]

May 21, 2019 9:23:05 GMT jackrae said:

Here's a link to the article www.model-engineer.co.uk/sites/7/documents/passenger%20car.pdf
It's in the public domain so as long as you're not selling it as your own work or manufacturing and selling passenger trucks based on the article the word-police won't be bothered.

Its an ME article openly available on the ME website copyrighted by My Time Media 2014 (the owners) so I'd guess they are happy for anybody to have a copy for their own use.

Pete