Point Construction pre-grouping.

[FrankWright]

Point Construction pre-grouping.

I'm looking at modelling a pre-grouping (SR) station, where the trackwork was laid around the turn of the century, with 72lb flat bottom rail, and fang bolts to the sleepers. The period I'm interested in is 1920-1930 or so, so no bullhead rail, chars, or standard "A" or "B" turnouts. I'm OK with a track plan, and enough period photos exist to model the FB rail/sleeper configuration, on straight sections at least.
The purpose of this posting is to discover how FB loose-footed switches were built in this era, and how to model them. There were no chairs on straight rail sections, but how were the switch blades mounted? Did they just bear directly onto the sleepers? Do any period track photos/diagrams exist, especially where facing point locks are fitted?
I'll probably be using Peco code 60FB NS (aka SR conductor rail) onto PCB sleepers. I've tried using the S4 Code 55 steel, but it's a pain to solder, and glue solutions will still leave me the dropwires and crossing V's to sort out. Switches with no slide chairs look dreadfully "unfinished" and I'm sure I'm missing something somewhere.
Thanks in advance.
Frank Wright

[Martin Wynne]

Hi Frank,

I can't answer your questions, but this picture of preservation n.g. practice is typical of the fittings for light-rail flat-bottom switches.

ng_switch_fb.jpg

Martin.

[FrankWright]

Martin: Thanks for the picture.

It was obvious that the switch blades didn't lay directly on the sleepers, but I couldn't find a photo or reference to explain how it looked.
Don't you just love the bits of spurious packing heading back towards the crossing V?

Frank Wright

[Armchair Modeller]

The sleepers under the point blades are likely set slightly lower in the ground than those under the rest of the track, to allow for the depth of the slide plates (or whatever they are called). Sorry if this is stating the obvious.

[John Palmer]

The switch ahown in Martin's picture does not make use of extensions of the stretcher through apertures in the stock rails, nor is it carried on heel plates. That means there is nothing to restrain the tendency of such a loose heel switch to pivot in the vertical plane on the bearer closest to the heel as a wheel approaches its joint with the closure rail, thereby causing the switch toe to rise. This may also be a problem to be faced in a 4mm representation of such a switch.

I can see no sign of it in Martin's picture, but I wonder whether any part of the foot of either the switch or the closure rail has to be removed at the heel joint, in order to accommodate the required horizontal rotation of the switch. This isn't a problem with bullhead rail so far as i am aware, but the greater width of the flat bottom base might limit excessivley the extent to which the switch can pivot.

[jon price]

As far as I can see the throw bar joining the point lever to the center of the tie bar goes underneath the rail, thus limiting the ability of the blades to rise.

[James Wells]

I can see no sign of it in Martin's picture, but I wonder whether any part of the foot of either the switch or the closure rail has to be removed at the heel joint, in order to accommodate the required horizontal rotation of the switch. This isn't a problem with bullhead rail so far as i am aware, but the greater width of the flat bottom base might limit excessivley the extent to which the switch can pivot.

A suitable rail gap should be sufficient to allow the blade to pivot without the foot or either piece colliding on the real thing - you can make out the gap in the photo.