4.
Those are
the
four characteristics and functions that a design of rail needs to provide to be effective
when installed within track.
Now lets look at these in more detail
Before we do, can I please ask a favour.
If you are finding this video useful please give it a like and subscribe to the channel.
This helps me grow the channel, and keep producing these videos.
Thank you.
So now lets look at these characteristic in a bit more detail
First up
Hard unyielding surface to carry wheels
- The primary function of the rail is to carry the wheels of the trains.
These wheels have a rigid steel tyre which contacts the rail.
The rail must be made of a material that is hard and unyielding so that it does not rut
or deform under this load or contact.
This function has remained the same since the first conception of railway tracks.
Next, the rail itself has to act as a beam, and transmit the load of the train, from the
wheels, to the sleepers and the rest of the track system
Act as a beam and transmit wheel, and thereby train, loads to the sleepers
- As the rail is the surface that directly contacts with the wheels of the train the
load of the trains is transferred to it as the trains pass.
This load is concentrated in a relatively small contact patch.
The rail then distributes this load downward, through the rest of the track system, firstly
to the sleepers and then to the ballast.
The surface area of these two components increases, distributing the load over a increasingly
larger area.
This creates the loading triangle you maybe familiar with.
- An important thing to also take take into account is that, on sleepered track, the rail
is only fully supported at set intervals.
These intervals are where the rail sits in the baseplates, on the sleepers.
In the space between the sleepers, where the rail is un supported, it deflects under the
load of the train.
This creates bending and shearing forces in the rail.
Therefore the design of the rail needs to be such, that these forces are resisted, and
do not permanently deform or damage the rail.
The third characteristic is that the rail needs to act with the wheel surface, to assist
in steering the train around curves
Act with the wheel surface to steer the trains
- The design of the gauge corner of the rail, specially its radii, is such that it is geometrically
compatible with the design of the wheel tread and flange.
When it comes to curves within the track, the interaction between the rail and the wheels
respective profiles helps, along with the cant of the track, to steer the train.
Lastly, new designs of rail must be such that they are able to under, or perform certain
secondary functions
Secondary functions
Given that rails are a fundamental part of the rail, therefore always present, they are
also utilised by other railway disciplines.
The other disciplines utilise the conductive properties of the steel, from which the rail
is formed to convey currents.
A key example of this is in track circuit train detection systems, critical part of
the overall signalling system for the railway.
They are also used by the returns for OLE and other traction systems.
So there we have the fundamental characteristic of a rail.
you can see that each is as important as another.
It is also good to remember that rails have secondary functions as well, that are critical
to other parts of the railway system.
I hope you have found this video interesting and informative.
If you want to find out about other railway component there other videos on the channel
covering sleepers and ballast
Thank you for watching.
Please don’t forget to subscribe!