British Railways OLE, part one, Plain Track

[Clive Mortimore]

Until last year I had a website that covered 25 KVa OLE, the host company changed things and I let the site die. I have considered doing a new site but today following the discussion on the Dapol OLE thread http://www.rmweb.co.uk/community/index.php?/topic/16442-Dapol-announce-oo-ole/ I decided to put a modified version of the website on here in a series of threads. I am modeller who has never worked for the railways therefore my information has been gleaned form what sources of information I have been able to get my hands on therefore I hope that other members on here can add to the threads with further information.

 

Much of the information will be historic as my own interests do not go much beyond the 1980s so I welcome any information on newer systems.

 

Plain track

 

I will describe the overhead wiring for a section of plain track without any point work, bridges, stations etc.

 

Stagger.

 

The wires on plain track are held above the line normally by cantilever mast, arranged so that the contact wire zigzags as it goes along. This is called stagger, and is arranged in this fashion to create even ware on the pantograph of the locomotives and multiple units.  The cantilever mast are positioned opposite each other on twin track, there is a push off assembly which holds the contact wire away from the centre line towards the centre of the two tracks. Above the other track is a pull off assembly that pulls the contact wire towards the outside of the track. The distance from the centre line of the track and the position of the contact wire at the registration point (where it is held by the mast) is 9ins for Mk1 OHLE and 230mm for Mk3. If working in 4mm scale this is 3mm.

 

Contact Wire Height.

 

With Mk3 equipment the contact wire height is 4.7m, slightly lower than Mk1 which is 16ft or 4.864m. This height can vary where there are level crossings, over bridges, depots and yards.  With early overhead schemes the height was greater in station areas as well. All these variations will be covered later.

 

 

This photo shows the stagger. Note the alternative use of push-off and pull-off mast. This is non-typical Mk1 cantilever mast using round post as found on the Chelmsford to Colchester section of the GE line. Photo taken on a level crossing at Kelvedon.

Mast Spacing

 

The distance between each mast is called the span. Masts are spaced the maximum distance apart where possible. The maximum design span is 73m (958mm in 4mm scale),and the minimum is 13m (170mm in 4mm scale). Were mast are of unequal distance apart the difference between them must not be over 20m (262mm).  There are many governing factors, which determine the distance for each span, these include the physical layout of the railway, where the points and junctions are, over bridges, under bridges and viaducts, stations, signals, gradients etc. Another important factor on the real railway is side wind, not a problem with model railways but one worth considering if you are modelling a line going across exposed fells or the fens. When the span is being calculated the “blow off”, sideways displacement of the contact wire due to strong wind should not allow the wire to go outside the pantograph sweep and the two loose contact with each other.  So in areas of high cross winds the spans are reduced in length.

 

Types of Overhead

 

Fixed Termination Equipment

 

This is found on older systems like the GER suburban lines and where wire runs are short, e.g. terminus stations. The contact wire is pre tensioned and is supported either end by heavy anchor mast.  This type of equipment is preferred on tight curved track as balanced weighted equipment cannot overcome the loads imposed by drag from the pantograph.  

 

Automatic Tensioned Equipment

 

This more commonly found and uses balance weights each end to keep the tension preventing the contact wire from moving out of place due to temperature changes, wind, and displacement by the pantograph of a moving train. In the centre of each length of wire is an anchor point, without this the wire would creep towards one balance weight due to being pulled along by the pantograph.

 

 

Tension Length and Number of Mast

 

On automatic tensioned equipment the maximum length is 1970m, from the anchor mast in the centre to each overlap at the ends there should be 14 masts. Where the mast are closer than this the wire length is shorter, the number of mast is the governing factor not the length of wire run until 1970m is reached. Crossovers, sidings, loops etc have shorter lengths with less than 14 masts from anchor point to balance weight.

 

The distance between the overlaps on the GER suburban lines is approximately 1 mile. There are 28 masts from one end to the other. Due to the contact wire being fixed at each end there is no need for a mid point anchor.

 

Mk1 and Mk3 mainly used cantilevers on single and double line plain track. The older 1500v DC systems of the GER and Woodhead route used portals.

 

Using the above information if your model layout has no points, obstructions etc and the track is straight then provided the number of mast is less than 14 the overhead will be cantilevers set as to give a stagger spaced at a maximum of a scale 73m.  Most model railways are not that simple, we like our stations with their sidings, loops etc. We also like bridges and tunnels, and most of us have sections of curved track.

 

Even if the layout was just a section of plain twin track how nice it would be to model a mid point anchor, or an overlap or even a feeder station.

 

 

 

 

 

 

Edited May 4, 2013 by Clive Mortimore

[Dagworth]

So glad to see this information reappear on the web Clive, thanks for putting it back up.

 

Andi

[Tase]

To echo Andi's comment above thanks for putting this info back into the public domain. It's been sorely missed and will no doubt benefit a lot of people out there.

[Natalie]

Ditto what Andi and Tase has written. Your original site (and your excellent CDs of drawings too) has been very useful in giving me an idea of how things are actually installed. It is responsible for me looking skywards and gazing - and photting- the wiring and equipment provided. Nuneaton certainly has a good variety where it has been joined by some new portals of the type i/c a diamond cut out in the span. Nuneaton also has a bit of trolley type wiring for the down holding sidings- I have tried to work out how the catenary wire is terminated- I assume it is simply provided i/c an insulator and attached to a mast/portal. Unfortunately I couldn't confirm this visually as there is quite a lot of wires in the vicinity and the staring at it was making my eyes hurt...Maybe it is worth posting some photos for expert identification and for others to take an interest in.

 

I do have one little question though- IIRC there were instances were a contact wire would cross another one- such as over a crossover road (rather than say being strung from one mast, run alongside an existing contact wire (for the running line) then diverges over the crossover then runs alongside the running line contact wire for the other line for a short distance before being terminated)- would this not produce a 'bump' for the pantograph head and potential dewiring and all the fun that entails?

 

EDIT- As an afterthought do you have anything on the SReg trolley-type overhead wiring? I have photted from Kew a couple of wiring plans dealing with the application of OHL (and also shows the transition from 3rd rail and where things like the 'raise'and 'lower' boards were located and the type of structure etc utilised) from the Ashford area. Are these (ie copies of my photo files) of interest to you- or to anyone else for that matter? Wonder if it worth posting these up as well and see if it promotes any discussion. I think I have also photted a couple of wiring plans too for the LMR 25Kv  (from TNA, Kew) which IIRC are from Manchester Piccadilly. Would need to confirm this though.

Edited May 4, 2013 by Natalie

[Clive Mortimore]

Hi Nat

 

I think I know what you are asking. Both the running line and the crossover wire, or point wire are held at the same height by the registartion arms. At the point of crossing the cross over or point wire runs over the top of the running line. The pantograph makes contact along both wires as it approaches where the wires cross, for a short time it is only in contact with the running line wire as the crossing wire is lifted over the running line wire.

This photo shows the point wire crossing over the rnning wire, and both wires the same height at the registartion arms.

[Clive Mortimore]

Hi Nat

 

Photos of OLE in any form are most welcome.

[Dagworth]

Clive, are you aware of this collection?

http://rugby-parkway.nstemp.com/catenary/gallery.html

 

Andi

[Clive Mortimore]

Hi Andi,

 

Cheers for the link, there are some nice photos of UK1 OLE. I will do a thread on UK1 as part of this series.

 

Clive

[Titan]

One further little detail which might be worth mentioning is the "cross contact bar" used at crossovers. This is a very short length of spare contact wire which is clamped to the main wire, but runs over the top of the crossover wire. You can just about see it in Clives photo.  The reason for it is that pantographs lift the contact wire as they pass along. No problem when running on the main wire, it is underneath the crossover wire and both are lifted together. However, if a pantograph is running along the crossover wire, then unless the two were connected by the cross contact bar, the pan could lift the crossover wire without lifting the main wire to match and the pan horns could 'hookover' the main wire and cause a dewirement. With the bar in place both wires get lifted no matter which direction the pan comes from.

 

Typically the amount of 'uplift' designed for is in the region of 230-300mm, depending on system, linespeed, wire height etc.  In practice though it is usually not anywhere near that (unless its the rear pan of a 10 or 12 car class 309 at 100mph which will have everthing bouncing all over the place!!!)

Edited May 5, 2013 by Titan

[Clive Mortimore]

HI Ian

 

I will post a drawing showing the uplift of the contatct wire when I get back to my main computer.

 

Ah a AM9 doing a ton .......as a passenger it would seem smooth

[trisonic]

Mant thanks for starting this thread, Clive!

 

Quick question from growing up in Shenfield - why did the early BR DC system apparently have the wires so high compared to the later AC? I'm not imagining it am I? The early EMU's  to Shenfield out of Liverpool Street all look like they are standing on tippy toe!

Yeah, I know I was shorter in the late fifties....

 

Best, Pete.

[Clive Mortimore]

Hi Pete

 

You are correct, the GE system contact wire height was higher in station areas where loco crews might be pulling the coal forward in the tenders. It was adjusted lower I think when it was converted to 25KVa. In Ilford Car Sheds the raised contact wire remains. Andi hopefully will be able to tell the story of the first 86s when they were at Ilford. 

 

Clive

Edited May 5, 2013 by Clive Mortimore

[Dagworth]

Ah yes, the first 86 into Ilford...

Pan has its height limit set for WCML equipment, locos tries to drive into ICS, pan goes up with the wire, pan reaches its overheight trip and comes down in a hurry... loco stops requiring assistance... 

After that all the GE 86s had to have their overheight settings tweaked to cope with the high wires.

 

EMUs don't have overheight switches, the pan will keep raising until it breaks its back.

 

Andi

[trisonic]

Here's a shot of the eastern carriage sidings at Shenfield in 1951 - just for info.

 

http://dewi.ca/trains/london/pix/n14_3_2.jpg

 

 

Cheers, guys,

 

Pete.

[Clive Mortimore]

Drawing demonstrating the uplift of the contact wire as the locomotive passes under it and the movement of the registration arm.

 

[bescotbeast]

Clive I've got this drawing of a Portal structure at Aston station on the Grand Junction that may of be use to others as it's got dimension

I have also got a large selection of OHLE pictures from around Stafford and Stoke of Portals, masts, Tensioners and Termination masts.

                                                                                  Simon

[Clive Mortimore]

Hi Simon

 

Thanks for the drawing. I intend to do a separate thread on OLE through stations as there are so many variations.

 

The plan for the threads is something like,

 

Plain track.....done

 

Curved track

 

Multiple tracks

 

Curved multiple tracks

 

Mid-point anchors

 

Overlaps

 

Crossing and points

 

Stations

 

Over bridges and tunnels

 

Level crossings

 

Span wires

 

Feeder stations and neutral sections

 

Tramway

 

UK1 rebuild of Mk1

[porkie]

Thanks for posting this thread, its been a great help on my layout.

 

Cheers

 

Phil

[Bartb]

I took this picture in Norwich a few years ago, thought it might help.

[jonathan452]

A question if you please.

 

I noticed on Saturday what looked like a Mk1 lattice portal at the beginning of the Richmond divergence (south of the bridge over the West Coast Main Line) on the HIGH LEVEL lines at Wilesden Junction.

 

I was of the impression that this section of line had been electrified (converted from third rail) in the early nineties hence featuring the Mk3b design, and that no overhead ac electrification was installed on this section under the original West Coast scheme.

 

I had also thought the only locations where Mk1 and Mk3 equipment co-existed was at various locations between Mortherwell and Glasgow Central.

 

Maybe the portal in question was recovered from elsewhere?

 

Many thanks in advance for any explanations,

 

EDIT Location - https://www.google.co.uk/maps/@51.5298143,-0.2447038,31m/data=!3m1!1e3

Edited August 10, 2015 by jonathan452

[Clive Mortimore]

Hi Jonathan

 

Haven't a clue about this portal. It does look like Mk1 style. Using the Bing maps birds eye view it could also be made from Mk3 twin cantilever parts. The Bing maps images do show it to be the center mast for a overlap.

 

As for Mk1 and Mk3 being seen together, it happens were new systems have been added, take the GER lines for an example, there is the Lea Valley route, Clapton to Cheshunt, Copper Mills Junction to Stratford, Romford to Upminster, Witham-Braintree, Wickford-Southminster and at Colchester to Norwich and Harwich.

[David Hibbert]

Hi Pete

 

You are correct, the GE system contact wire height was higher in station areas where loco crews might be pulling the coal forward in the tenders. It was adjusted lower I think when it was converted to 25KVa. In Ilford Car Sheds the raised contact wire remains. Andi hopefully will be able to tell the story of the first 86s when they were at Ilford. 

 

Clive

The higher contact wire was not to facilitate pullingthe coal forward in tenders, though that would have been a bonus, the higher wire was tom allow the firman to take on water. Level crossings over main roads also had higher contact wire to allow double decker busses to pass.

[David Hibbert]

Here's a shot of the eastern carriage sidings at Shenfield in 1951 - just for info.

 

http://dewi.ca/trains/london/pix/n14_3_2.jpg

 

 

Cheers, guys,

 

Pete.

I walked have the GE lines many times and this photo looks more like the Country end at Shenfield. It certainy is not Ilford.

[David Hibbert]

A question if you please.

 

I noticed on Saturday what looked like a Mk1 lattice portal at the beginning of the Richmond divergence (south of the bridge over the West Coast Main Line) on the HIGH LEVEL lines at Wilesden Junction.

 

I was of the impression that this section of line had been electrified (converted from third rail) in the early nineties hence featuring the Mk3b design, and that no overhead ac electrification was installed on this section under the original West Coast scheme.

 

I had also thought the only locations where Mk1 and Mk3 equipment co-existed was at various locations between Mortherwell and Glasgow Central.

 

Maybe the portal in question was recovered from elsewhere?

 

Many thanks in advance for any explanations,

 

EDIT Location - https://www.google.co.uk/maps/@51.5298143,-0.2447038,31m/data=!3m1!1e3

The welded rod portal was a spare new one made up of metric angles and rod but generally as per the original Mk1 drawing in the 3000 series.

[David Hibbert]

Clive I've got this drawing of a Portal structure at Aston station on the Grand Junction that may of be use to others as it's got dimension

2 track Gantry Blueprint.JPG

I have also got a large selection of OHLE pictures from around Stafford and Stoke of Portals, masts, Tensioners and Termination masts.

                                                                                  Simon

These drawings are correctly known as CROSS SECTIONS. Every mast/portal/headspan location has one.