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topic: 747Fishplates
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posted: 1 Mar 2009 19:42

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richard_t
 
Nr. Spalding, South Holland - United Kingdom

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I asked on a recent thread, about the bonding of TC's over fishplates. I was out on Friday, and this first shot shows a fishplate with the bonding wires on the outside of the rail. I've tried to work out some of the lengths between the holes. On the left the holes are vertically aligned and around 25" from the end of the rail, whereas the holes on the right are horizontally aligned, with one being 22.5" and the other 24.5" from the end of the rail. This shot was at Carpenders Park on the DC lines, so the fishplate on the other rail was DC bonded with a much thicker cable. Note how the wires have been tucked inbetween the rail and the chairs and the larger joint chairs. Richard.
Attachment: attach_501_747_fpb2.jpg 669
Last edited on 1 Mar 2009 19:51 by richard_t
posted: 1 Mar 2009 19:49

from:

richard_t
 
Nr. Spalding, South Holland - United Kingdom

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The next shot I think is a little more interesting - this was taken at the yard in Bletchley (from a public foot path) - note the amount of rubbish!

From the front working back, here the bonding doesn't look like it's welded to the rail, and is just bent over through the hole. The left side is horizontally aligned, but the right is a bit all over the place! Here the wire is on the inside of the rail.

The next rail, and do note how the fishplates aren't aligned, the bonding wire swaps from inside to the outside of the wire - this is very common in Bletchley yard.

Finally, just in the background to the top right it seems that this fishplate is on back to front with the nuts on the inside. Or is it that the others are the wrong way around?

I hope that's of use/interest to others.

(PS: Skirted fishplates would be nice from a manufacturer or two :cool:)
Attachment: attach_502_747_fpb1.jpg 695
Last edited on 1 Mar 2009 19:52 by richard_t
posted: 2 Mar 2009 18:51

from:

Sharpey
 
Telford - United Kingdom

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Perhaps I can shed a little light on the practice of rail bonding. Having fitted 100's if not 1000's of them over the years as a professional signalling type person.

The normal practice is to fit 2 galvanised bonds over each rail joint, although in some areas you may find 3 fitted on the traction return rail. As correctly summised in the original post they are not required where track circuits are not fitted.

They can be found normally on the inside of the rail and outside of the joint, but this will not always be the case. Where access is difficult they may be fitted on the outside although this is rare, on other occassions they may be on the outside of one rail to the inside of another, this was a practice some years ago to keep the bonds out of the way of the rail joints. They should always be installed with enough slack in them to allow the fishplate to be removed without breaking the bonds and to allow for some "pulling back" of the rails in plain line.

The bonds are fitted by drilling 2 x 9/32" holes in the rail in the first clear bed after the joint, as can be seen in the pictures. The bond then has the ends bent over, as they are supplied straight (approx 5' long) and in large bundles (100 bonds I think). The bent over ends are put through the holes and secured by hammering in a tapered channel pin. The bond being somewhat smaller than the hole this will be gripped by the insertion of this pin. There is no welding involved with this type of rail bond.

I hope that this makes things a little clearer.

posted: 3 Mar 2009 08:51

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richard_t
 
Nr. Spalding, South Holland - United Kingdom

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Many thanks for the offical word!

I don't suppose you know the gauge of the wire?

Again, thanks!

posted: 10 Apr 2009 18:00

from:

richard_t
 
Nr. Spalding, South Holland - United Kingdom

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To answer my own question, from "British Railway Signalling Practice - Electrical No. 9 Track Circuits":

1. A cotton-covered stranded wire - say 19/0.36" - with a lug sweated on each end, the lugs being driven into holes in the rails as described in the previous section.

2. A bond of a sign conductor - possibly No. 8 gauge - secured to eht rails be means of channel pins.

3. Short flexible bonds welded to the heads of the rails.

4. Flexible bonds of high current-carrying capacity installed under the fishplates and pinned to the rails. Such bonds are more usually associated with track circuits on 3rd rail traction systems on electrified lines.

Richard.



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