SR Conductor Rail info. This may help you.

[dasatcopthorne]

I knew I had this somewhere and during a tidy up it has come to light.

 

I cannot remember how I came by it or who did the drawing but here it is.

 

I think the pot spacing has now stretched to 5 sleepers. May be because conductor rail is lighter. Only guessing.

 

Hope it helps some of you. Please spread it around.

 

Dave.

 

 

Edited January 8 by dasatcopthorne

[Fair Oak Junction]

Very helpful, thank you for posting it! 👌

[dasatcopthorne]

UPDATE.

 

someone on another group has advised that things have changes since 1971.

 

At the least the double dips on the ramps have gone and the pot spacing is now often every 6 sleepers except on curves.

 

Dave

Edited January 9 by dasatcopthorne

[Hal Nail]

Amazing timing as I bought a 73 yesterday and was intending to look into 3rd rail details.

[Pete the Elaner]

Take a look at the real railway. You may see all sorts of unusual oddities & exceptions.

 

I have been told numerous times that the pots are every 4th sleeper, but I have seen for myself on the Watford DC lines that they are often 5 or 6 sleepers apart.

 

[roythebus1]

Today's EMUs have far lighter collector shoes than the old stock I used to drive and the design has changed.

 

It would be worth copying this across to the Handbuilt Track and Templot group for reference, expecially the track measurements..

[Nearholmer]

The standard was changed from every fourth to every fifth sleeper IIRC in the 1980s, possibly in advance of the Hastings Electrification. I remember discussions of the issues taking place in the office about the pros, cons and factors, and again IIRC the deciding point was the rigidity of 150lb/yard CR and the experience with it up to that time. Lots of ETE standards were rationalised at roughly the same time: dispensing with wooden protection troughs around track feeder cables; dropping of the mass of different DC cable lugs in favour of one type; reducing the number of different pot designs; I think dispensing with the two-gradient ramp-ends, etc. The same sort of thing was going on with HV cabling and with substation plant too, because it was obvious that there were economies to be made in the light of more modern materials/techniques. Not all of it worked first time: I remember presiding over a failed attempt to change the way top-caps were fitted to dough-moulded ‘pots’, which was a total failure!

[johnb]

 Last year I was on Arundel station and in the length of a few metres on the same track, I  spotted pots spaced at 4, 5 and 6 sleeper intervals. Mostly though they were at 5 sleeper intervals, I was wanting to check that my layout was correct in using 5 sleeper spacing

[Southernman46]

6 hours ago, Nearholmer said:

The standard was changed from every fourth to every fifth sleeper IIRC in the 1980s, possibly in advance of the Hastings Electrification. I remember discussions of the issues taking place in the office about the pros, cons and factors, and again IIRC the deciding point was the rigidity of 150lb/yard CR and the experience with it up to that time. Lots of ETE standards were rationalised at roughly the same time: dispensing with wooden protection troughs around track feeder cables; dropping of the mass of different DC cable lugs in favour of one type; reducing the number of different pot designs; I think dispensing with the two-gradient ramp-ends, etc. The same sort of thing was going on with HV cabling and with substation plant too, because it was obvious that there were economies to be made in the light of more modern materials/techniques. Not all of it worked first time: I remember presiding over a failed attempt to change the way top-caps were fitted to dough-moulded ‘pots’, which was a total failure!

Indeed - we (3 of us including your good self) walked from Brookwood to Farnborough on 25th May 1984 surveying the insulators on all 4 lines / whether there were anchor insulators etc, etc as part of this exercise - taking a hearty meal (alcohol-less) in the lineside pub near the Basingstoke Canal Aqueduct at Deepcut - working out that accessing Deepcut TP hut from track level is a very stupid idea (more steps than the Eifel tower) and generally having a fine day out.

I managed to photograph 37050 on the Micheldever tanks in both directions too (s'how I know the date - not that sad)

Ultimately the insulator spacing went to 6 for new 150 and 5 for existing 100/106, JMcC trying to reduce electrification costs - 8 was tried but as you say the 150lb/yd c/rail became distinctly lumpy at this spacing.

 

It is worth remembering that some of the 100lb CR out there on the Southern region in daily use is 100 years old now and the majority of the 106lb in the London area in service since 1955 - some will have seen 2-3 track renewals because if the CR is in satisfactory condition it will be re-installed - had to fight very hard on a few occasions in the past to get the CEngr to include the CR in a renewal.

Edited January 9 by Southernman46
waffle added

[martin_wynne]

See also:

 

 http://www.clag.org.uk/3rd-4th.html

 

 

[dasatcopthorne]

I have the information on the current practice but am awaiting permission to share it.

 

Dave.

Edited January 11 by dasatcopthorne

[dasatcopthorne]

Here are the three diagrams made available to me from someone involved in current design practice.

 

Dave.