Re: trams riding on flanges

["chris 'fufas' grace" <chris@transdata.co.nz>]

> "Rod [comtrain]" wrote:
> 

> > Railway Engineers taper a wheel from the outside edge  gradually increasing
> > the diameter until it becomes the flange. As it approaches the flange, the
> > diameter increases at a much faster rate.The back to back measurement of the
> > wheelset, is actually slightly shorter than the gauge of the track.
> > The rails are stepped slightly with a base plate, so that the head of the
> > rail is a closer match to these tapered wheels.

I do not think rails are still inclined inwards. This practice ceased
when flat bottomed rail replaced bullhead. Since bullhead rail had a
much smaller base, inclining it was easier than with the large base of
flat bottom. The major problem was switch and crossing work. It
required much more complex engineering with flat bottom to keep the
inclination through the crossings.

Some considerable work on wheel tread profile was done in the 1960s (I
can give references if you like) and the profiles now used do not
require inclined rails. There is a small increase in gauge on curves,
which, together with the new profile, gives the differential effect.

As to trams, as far as I know the idea of riding on the flanges
through switch and crossing work is not new and has been around since
the earliest days. Not all systems use it, but the idea is that since
junctions and crossings are much more frequent in tramways than in
railways, there is quite a shock loading on the equipment in the tram
itself which causes unreliability. Riding on the flanges reduces this
substantially. The flanges are designed to allow this.

The other factor is track wear since the frequency of service on a
central city junction or crossing is much greater than on a railway
line, and track wear is consequently greater. 
Tram junctions are usually cast in one piece and are expensive. riding
on the flanges saves on maintenance because all that is required is to
build the flangeway up by welding. The ride is better for the
passengers, too.


-- 
For a dining "experience" visit the "Killer Prawn" in Whangarei!
Be served and charged for food *without even ordering it*!
Let the staff treat you with undisguised condescension and contempt!
Experience the total incompetence of the management! Book today!