Super Low 45s. Fifty years late?

[Tiny Tim]

DRS are now using W.H. Davis 'Super Low' wagons to carry 9'6" high shipping containers over non-gauge-enhanced routes. Does anyone know why this simple solution wasn't available many years ago? I'm not saying it isn't a clever bit of engineering, but it isn't rocket science. Why did nobody see that instead of spending millions bashing bridges and tunnels about it was possible to make the wagons lower?

 

[asylumxl]

I haven't a clue and am only guessing. It could be something to do with bogie designs not being compact enough before to make it viable. Being compact as well the wheel radius may make for low maximum design speeds.

 

[ChristopherJ]

Flat wagons designed with a low deck height above the rail aren't a new concept. Freightliner use a variation called the Lowliner or FLA.

http://www.porterbrook.co.uk/images/pic_library/pdf/FLA Wagon.pdf

DBS also use a variation designated as the FAA.

http://www.porterbrook.co.uk/images/pic_library/pdf/FAA Wagon.pdf

 

[swt_passenger]

DRS are now using W.H. Davis 'Super Low' wagons to carry 9'6" high shipping containers over non-gauge-enhanced routes. Does anyone know why this simple solution wasn't available many years ago? I'm not saying it isn't a clever bit of engineering, but it isn't rocket science. Why did nobody see that instead of spending millions bashing bridges and tunnels about it was possible to make the wagons lower?

It isn't a new concept at all.

However, quite a few press reports of WH Davis's new wagons do seem to read as though they are a completely new idea. No idea why the rail media seem to have taken this view in so many articles - unless they are all quoting the same original material badly...

 

[Wyvern]

Why haven't such wagons been used before? Perhaps smaller wheels? Roadholding?

 

[swt_passenger]

Why haven't such wagons been used before? Perhaps smaller wheels? Roadholding?

They have been used before - that's what the first image above (the Freightliner FLA with the small wheels) is showing.

 

[Wyvern]

So why were/are they not used more? What disadvatage if any did Freightliner find with them?

 

[DarloRich]

well a couple of problems are noted on the pda's attached to a previous post.......

 

[jopsuk]

length is certainly an issue- especially with the FAA type.
Smaller wheels give an issue with bearings, as they have to rotate more for the same forward speed
Can the FAA and FLA take 45' containers? The pictures I can see only show them with 40' ones. 45' are becoming more common, they're extensively used in the US.

 

[Tiny Tim]

The FAA has the fairly major drawback of increased length, but surely the FLA had potential? Smaller wheels may increase revolutions, but these wagons are rated for 75mph, hardly speeds likely to cause excessive wear to modern bearings. We're not using tallow as a lubricant any more.

 

[DarloRich]

The FAA has the fairly major drawback of increased length, but surely the FLA had potential? Smaller wheels may increase revolutions, but these wagons are rated for 75mph, hardly speeds likely to cause excessive wear to modern bearings. We're not using tallow as a lubricant any more.

you might be suprised!

There is something tucked away in the old memeory banks about track impact forces but due to the level of beer consumption over the weekend and the subsequent destruction of brain cells i will have to ask around. Sorry

 

[sprinterguy]

The FAA has the fairly major drawback of increased length, but surely the FLA had potential? Smaller wheels may increase revolutions, but these wagons are rated for 75mph, hardly speeds likely to cause excessive wear to modern bearings. We're not using tallow as a lubricant any more.

It's not a case that the FLA wagons "had potential". They're in regular, daily revenue earning service and have been for many years now: The first production FLA "Lowliner" container flats were introduced into service in 1990, while Freightliner perpetuated the design with a further order for an additional 80 wagons to the same design in 2004.

This document provides plenty of information on the development of low-height container flat wagons:
http://www.ltsv.com/downloads/w_profile_053.pdf

And here's a picture of one of the original 1990 batch of vehicles:
http://paulbartlett.zenfolio.com/fla/h3F035032#h3f035032
--- old post above --- --- new post below ---

So why were/are they not used more? What disadvatage if any did Freightliner find with them?

They are still regularly used, and have been used for a number of years, as swt passenger keeps saying. See above.

 

[Tiny Tim]

I guess that smaller diameter wheels might create a different impact on the rails, but would this be significant? Both the FLA and the FAA (with full size bogie wheels) are rated for 75mph which implies that wheel size wasn't considered a major problem.