Push-pull services

[timbowilts]

So far as compatibility with the GW's mechanical auto linkage goes, the stock acquired at the grouping from the Taff Vale and Cardiff Railways seems to have been compatible, but not that from the Rhymney.  I could probably at one time have told you if modifications were required to enable use with GW auto fitted locos; AFAIK these were all built to work with railmotors or converted from railmotors (as were many of the GW ones), but it is one of the things that have dropped through the holes in the Swiss cheese that my brain is made up of and I cannot recall it now...

 

Taff Vale and Cardiff Railway trailers survived into the 50s to be used with 4575 tanks on Cardfif suburban workings, but they seem to have remained in 2-car sets and not mixed and matched with the GW trailers, though they could be seen in the same train with the loco in the middle.  Again AFAIK but I would be happy to be corrected, they spent their entire working lives in the Cardiff area.

Regarding the ex Taff Vale stock, that most definitely required modification! The TV auto trailer system used a set-up of pulleys and wires carried at high level over the tops of the trailers and locos, very different from the mechanical under-the-chassis system used by the GWR.

 

Tim T

[Karhedron]

As far as I know only the GW were in the habit of sandwiching the loco between auto trailers, although all the others were fitted both ends.

In the GWR's case, I think the reason for sandwiching was the slop in the mechanical linkages was such that you could only have 1 intermediate vehicle between the driving coach and the loco. Any more than that and there was too much slop in the system to reliably control the loco. So if a P/P service required 3 or 4 coaches, the only way this could be done was by putting the loco in the middle. This was particularly common on the suburban services round Plymouth although it doubtless happened elsewhere too.

 

[meil]

Might be of interest: http://glostransporthistory.visit-gloucestershire.co.uk/Push%20Pull%20YTT.html

[Retro_man]

The Keighley and Worth Valley branch was run using a full "Pull & Push" set in BR days. Note the MMS designation. One set was made up of modified corridor coaches- see the thread soon the specialist MMS coach section on RMWeb.

 

 

Hello Barry,

 

Could you post a link to this please as I cannot find it using the search function?

 

Thanks in advance,

Steve

[MarkC]

As far as I know only the GW were in the habit of sandwiching the loco between auto trailers

The North Eastern sandwiched the loco between trailers on occasion too, Michael - photos of both BTP/G6 and O/G5 working such trains do exist

[Nick Holliday]

The LBSCR was another line that often ran trailers either side of the loco (D1)

[TheSignalEngineer]

Not Push-pull on each side, but there's a picture on the Rail-Online site of 41223 leaving New Street propelling the Push-pull vehicles and with a Gresley steel body BG in tow.

[The Johnster]

Regarding the ex Taff Vale stock, that most definitely required modification! The TV auto trailer system used a set-up of pulleys and wires carried at high level over the tops of the trailers and locos, very different from the mechanical under-the-chassis system used by the GWR.

 

Tim T

 

Yes, I'd forgotten that the TV's system relied on overhead wires and cables.  The lack of prior gear beneath the vehicles may have of course made it easier for the GW to install it's own system; AFAIK it used it's own locos exclusively and not any of the grouping acquisitions for auto work, but I suppose the Taff's and other systems must have lasted into 1923 for a short while while the work was being done.

[The Johnster]

The mechanical linkage of the GW's system limited it to no more than one intermediate vehicle, but I am not aware that the other railways' air or vacuum systems were able to accommodate more than this anyway; happy to be proved wrong!  Incidentally, the 'sandwiching' of auto locos on the WR extended to the Cardiff Valleys area in the 50s, as well as Plymouth where it had been a long standing feature, some two coach sets of trailers being gangwayed between each other.

[The Bigbee Line]

The LBSCR was another line that often ran trailers either side of the loco (D1)

I've seen pictures of a push pull set used for driver training on the South Eastern in connection with the electrification that had a driving trailer on each side of a loco (An H I think) that used the LBSC air control system.

[Oldddudders]

The mechanical linkage of the GW's system limited it to no more than one intermediate vehicle, but I am not aware that the other railways' air or vacuum systems were able to accommodate more than this anyway; happy to be proved wrong!  Incidentally, the 'sandwiching' of auto locos on the WR extended to the Cardiff Valleys area in the 50s, as well as Plymouth where it had been a long standing feature, some two coach sets of trailers being gangwayed between each other.

 

I don't think more than two vehicles were allowed to be propelled in passenger service, at least in them thar days. When Southern proposed propelling 8 vehicles on the Bournemouth Electrification I think eyebrows were raised here and there, but of course full electrical control throughout the train made it a sight more secure than mechanical or early pneumatic systems, I'm sure. 

[The Johnster]

Yes, electrical control is clearly superior, and easily implemented on modern traction which has electrical control in the cab anyway.  To do this in steam days would not have been impossible, as the technology is as old as Faraday, but servos to operate what were ultimately mechanical controls on the locos would have been more difficult.  How were the Paris suburban trains powered by 2-8-2 tanks controlled?  These are a fairly modern example of push pull with steam and multiple vehicles, and seem to have been very successful.

[kevinlms]

The LBSCR was another line that often ran trailers either side of the loco (D1)

I seem to remember that at least one early morning service on the LNWR, had 2 pairs of coaches either side of the loco. However, I think the 2nd pair was just a positioning move, perhaps after overnight cleaning or maintenance - swapping over a set maybe?

The sets then covered 2 branches.

[petertg]

A lot of very interesting information has come out in this discussion. However, the object of my original question was to find an appropriate RTR vehicle to insert between the locomotive and the autotrailer, namely would it be all 3rd or composite, brake or otherwise and corridor or non corridor since the autotrailer has no gangway.. I say RTR because I am not in a position to do any modification work for four main reasons: I don't have adequate tooling; I don't have the expertise; I don't have the required eyesight and I don't have nimble fingers, rarther swollen arthritic joints and often things seem to fly away from my fingers when I try to pick them up.

[TheSignalEngineer]

The LMS used conventional non-corridor coaches, both all third and composites, fitted with additional pipes at each end for the regulator and RCH jumpers for the engine bell. Hornby Period 3 coaches would be suitable almost as they are for renumbering those built after the change from torpedo vents to shell vents, so probably the lots built by the LMS in 1938 and BR in 1949/50. the lots built c1932/34 would need the roof vents changed.

[muswellmetro1]

On 06/05/2018 at 22:23, TheSignalEngineer said:

The LMS used conventional non-corridor coaches, both all third and composites, fitted with additional pipes at each end for the regulator and RCH jumpers for the engine bell. Hornby Period 3 coaches would be suitable almost as they are for renumbering those built after the change from torpedo vents to shell vents, so probably the lots built by the LMS in 1938 and BR in 1949/50. the lots built c1932/34 would need the roof vents changed.

There are diffrences in the van door layout between Lot diagrams but the major change is that the BR 1949/50 have an additional window, the period 111 last lms sets had no duckets and upright vacuum and motor pipes, whereas the post lms 1949/50 BR biult P&P had mark1 low vacuum and motor pipes and a window between the guards/driver door and the carriage end

[Nick C]

On 06/05/2018 at 09:51, Oldddudders said:

 

I don't think more than two vehicles were allowed to be propelled in passenger service, at least in them thar days. When Southern proposed propelling 8 vehicles on the Bournemouth Electrification I think eyebrows were raised here and there, but of course full electrical control throughout the train made it a sight more secure than mechanical or early pneumatic systems, I'm sure. 

The Southern had 3-coach pull-push services - Certainly on the Swanage and Lymington branches. Some of the ex-SECR "hundred seaters" 10-compartment thirds were fitted with through pipes to allow them to be used between a standard 2-car PP set and the loco.

[The Johnster]

The 2 trailers from the loco limit on the GW/WR was imposed by the physical restrictions of the mechanical and manually operated linkage; play in the system and friction made it impractical as a method of control more than 2 vehicles out.  But another issue soon also reared it's ugly. as with two 70' trailers the front of the train might be over 150 feet away from the locomotive's whistle, not to mention the bulk of it blocking the sound of the whistle to an extent for anyone on the track in front of the oncoming train, which is why GW auto trailers were fitted with warning bells operated by a foot treadle in the trailer cab.

 

I am not knowledgable about other railways' push pull systems, but clearly an air or vacuum system overcomes the limitations of mechanical linkage and more coaches can be used.  My eyebrows were raised a little by the Bournemouth 8 coach push pulls, but I never considered the control method an issue, rather questioned the stability of a relatively lightweight set of coaches pushed at 100mph by a powered set or loco.  This turns out not to be a problem even at 140mph on the ECML.  Did the LMS and Southern systems employ whistles or horns at the front of the propelled train?

[cheesysmith]

Iirc there was a limit of two coaches allowed to be propelled in passenger service by DOT. Just look at the early EMUs, where the motor coach was at one end to make detaching for maintenance easier and there were only two trailer coaches. 

[The Johnster]

In full pedant mode, Board of Trade in those days.  

[MJI]

On 04/05/2018 at 12:54, meil said:

Might be of interest: http://glostransporthistory.visit-gloucestershire.co.uk/Push%20Pull%20YTT.html

 

I went to school with him, his dad was woodwork teacher. I knew him as Mark

[Compound2632]

See this topic for more on the vacuum control system used on Midland/LMS motor trains:

 

 

 

[snowy1051]

Talking of length of trains for propelling, see this interesting photo. 

[snowy1051]

My totally 100% Tri ang Pull push train. I remember being interested in an article (was it Mr. Essery) in a Railway Modeller from about 1960 where it demonstrated how to convert a Tri ang brake third into a drive trailer. So I had a go and I still run the train. You may be able to see the solid wheels on the loco, that still runs very nicely. It's a shame Hornby didn't add PP gear to their R302, 47480, as that was one of the 5 Jintys  so fitted. Being an ex Midland man, Saltley, I had intended to model Brynamman, but doubted my sanity if restricted to 0-6-0 tankies!