Re: History of the building of the NE SG line.

[pcc@ocean.com.au (Les Brown)]

"Rod" <berlina@bigpond.com> wrote in aus.rail:

>Got me thinking about K crossings [this post] and as I usually sit in the
>Engine and only feel or hear them as I pass over I thought I would get down
>and have a look when we shunted Milos last night.
>Now when working in old yards like Tottenham, the Loco does feel like it is
>dropping into the "hole" as it traverses the K crossing, or frog, but in
>newer yards and on all main line crossings, very little bump is felt that
>could be attributed to dropping into a hole.
>You do hear a lot of noise and the loco can be moved violently sideways, and
>that seems to be the check rail forcing alignment with the 'frog'.
>Modern Points have welded blades tightly bolted to the K crossing, and the
>rails flex as the point machine moves the blades accross.The K crossing is
>replaceable, making repairs to the Points easier.
>watching the container flats going in and out of Milos, I could clearly see
>that the tread of the wheel, does not at any time leave a rail, it 'makes
>before it breaks' as it were. If you draw it out on paper you will see how
>it is done.

I'm sure there's a lot of wear, loose bolts, free play, etc, on a
frog, wing and check rails that would result in a wheel dropping down
in the frog gap as well as other strange movements at old sidings but
I'm not certain that the width of the tyre is wide enough to enable a
smooth transition from wing to frog, especially if the flange is hard
against the opposite rail and not the check rail. I do not know the
measurements of the distance between the outsides of the flanges and
the wheel tread width. Knowing both would enable you to work out with
reasonable certainty the likelihood of a wheel dropping into the
frog-gap.

I think that there must be determined somewhere an angle of a crossing
any greater at which you risk a wheel drop which is probably the
reason why 90 degree crossing are avoided where possible? The wear
would be horrendous, unless, of course, the wheels ride on the flanges
at these crossings. Don't Melbourne's Trams have a deeper than usual
flange for this purpose that prohibits their use on railway lines?

Les Brown