Running Gauge Dimension

[ac6000cw]

This is a really interesting thread - I'd never thought much before about the rails being inclined inwards (although it seems common sense once you think about it...).

One question - how common around the world is the 1 in 20 inclination value?

I ask because (from casual observation when I've been out there) American rails seem almost vertical, and a bit of web searching reveals that they use a 1 in 40 inclination instead.

 

[Joseph_Locke]

This is a really interesting thread - I'd never thought much before about the rails being inclined inwards (although it seems common sense once you think about it...).

One question - how common around the world is the 1 in 20 inclination value?

Very.

I ask because (from casual observation when I've been out there) American rails seem almost vertical, and a bit of web searching reveals that they use a 1 in 40 inclination instead.

Colonials always have to be different, but there again their idea of high speed isn't very so stable bogie performance at speed is less of an issue. Also be aware of the pitfalls of terminology; two rails at 1 in 40 is 1 in 20 towards each other ...

 

[civ-eng-jim]

This is a really interesting thread - I'd never thought much before about the rails being inclined inwards (although it seems common sense once you think about it...).

I'm sure all the scientists and engineers over the years who have studied the effects of rail inclination, wheel conicity, wheel/rail interface and wheelset kinematics will be delighted that their research can be concluded with "It's just common sense"

 

[XDM]

I'm sure all the scientists and engineers over the years who have studied the effects of rail inclination, wheel conicity, wheel/rail interface and wheelset kinematics will be delighted that their research can be concluded with "It's just common sense"

Come on, be fair, not grumpy. I suspect he means the principle of inclination is common sense, not the detail of it, i.e. the specific degree of inclination! But it is a fascinating thread, thanks to all contributors, & a subject which I confess was an "unknown unknown" for me. I had not even thought about it.

 

[najaB]

I'm sure all the scientists and engineers over the years who have studied the effects of rail inclination, wheel conicity, wheel/rail interface and wheelset kinematics will be delighted that their research can be concluded with "It's just common sense"

Don't get het up about it - it's 'common sense' that curved wing surfaces generate lift, but it's a long way from there to a 747.

 

[civ-eng-jim]

Don't get het up about it - it's 'common sense' that curved wing surfaces generate lift, but it's a long way from there to a 747.

It's a bugbear of mine as the term is banded round as if it's a sense or instinct which human beings are born with.

It may be regarded as "common sense" not to walk over the edge of a cliff or run out into a busy road but a two year old may do it until they have learnt the dangers of doing so.

Aspects of track engineering could be classed as "common sense" as it's obvious that a train can go quicker round more gentle corners that sharp corners....

Senses are developed over the years from ones experiences and interactions with the world.

There's good sense and bad sense, but not "common sense"

Anyway, back to the topic.....

 

[najaB]

It's a bugbear of mine as the term is banded round as if it's a sense or instinct which human beings are born with.

Common sense and instinct are two very different things. Saying that something is common sense just means that no specialist knowledge is required to understand the basic concepts underlying it - you can derive an understanding from deduction or from observation. As an example. it's common sense that in most cases a block of wood will float and a similarly sized block of concrete will sink. You don't need to know Archimedes' Principle to know that it happens, but you do need understand it order to explain *why* it is so (and also why some wood sinks).

 

[Ploughman]

And some things made of Concrete float.

 

[Joseph_Locke]

And some things made of Concrete float.

And many things made of wood sink. Simples!

 

[ac6000cw]

I don't regard 'common sense' as instinct (i.e. something you are born with) - it's learned knowledge that most people should be expected to have. We've long taught at least basic science in schools, and the concepts of action and reaction (equal and opposite forces), momentum (conservation of energy), applying force to objects to change their velocity (acceleration), resonances etc. are all things we come across in everyday normal life. A lot of people might not know or remember the scientific terms and explanations for those, but they are familiar with the reality of them.

To me, thinking about forces and energy is 'common sense' because I've grown up with an interest in science and engineering - so canting the rails inwards to match the basic taper of the wheels means that the downward force (weight) of the train transmitted to the rails on the flatest part of the railhead, which is also directly above the web, so it's the strongest path, and minimises the sideways component of the force on the railhead. So in theory you end up with the largest wheel-rail contact patch at the strongest part of the rail.

Sure, there is a lot of detailed research, knowledge and experience needed to go from a 'first principles' system design to a fully working, reliable and economic design - that's what engineering design is all about (I work in it, as an electronics designer), but the basic concepts are usually not hard to understand or analyse. Getting good, stable, ride of self-centering wheelsets at varying speeds I fully understand is very difficult in reality - it's a naturally resonant system which are always difficult things to analyse and control. Dealing with/avoiding unwanted resonances/oscillations is a perennial problem in my field of engineering too...