Couplings: 3 link vs. screw link

[truffy]

Can anybody tell me which rolling stock would be fitted with three link couplings and which would be fitted with screw link couplings, specifically on the SR in the '30s?

 

Would it be correct to assume, also, that the same fitting would be at each end of a wagon/van/carriage, and not just a hook alone at one end?

[jim.snowdon]

24 minutes ago, truffy said:

Can anybody tell me which rolling stock would be fitted with three link couplings and which would be fitted with screw link couplings, specifically on the SR in the '30s?

 

Would it be correct to assume, also, that the same fitting would be at each end of a wagon/van/carriage, and not just a hook alone at one end?

In essence, if it had vacuum brakes, screw couplings would be normal, and every vehicle was fitted with both a hook and a coupling at each end. 

 

Jim

[Steamport Southport]

Don't forget most fitted wagons would often use an Instanter coupling rather than a screw link. Even MGR Hoppers used them.

 

This thread here has some information on couplings.

 

https://www.rmweb.co.uk/community/index.php?/topic/125436-instanter-three-link-coupling/

 

Anything that would be used in a passenger train would be coupled with a screw link. If a vehicle wasn't fitted with one then you would use the one on the other vehicle. Couplings would be at both ends.

 

 

 

Jason

Edited March 19, 2020 by Steamport Southport

[jim.snowdon]

For clarity, I had ignored Instanters only on the basis that in the 1930s, as far as I am aware, only the GWR used them. Widespread adoption did not come about until into the BR period.

 

Jim

[Steamport Southport]

11 minutes ago, jim.snowdon said:

For clarity, I had ignored Instanters only on the basis that in the 1930s, as far as I am aware, only the GWR used them. Widespread adoption did not come about until into the BR period.

 

Jim

 

The LMS used them as well.

 

However in the 1930s most wagons were common user so you are just as likely to have a GWR wagon in your train as a SR one.

 

 

 

Jason

[The Johnster]

Yes, I think for the Southern in the 30s you can ignore instanters.  Incidentally, the BR version was different in profile to the original GW type.  They could be coupled in a short or long configuration, and unfitted trains with them in the long position (for ease of shunting) were restricted to 25mph running speed.

 

A way to think of it is to classify your stock in the way the real railway did.  Passenger rated stock, that is, passenger carrying vehicles and Non Passenger Carrying Coaching Stock, NPCCS, such as parcels vans always had pneumatic or hydraulic buffers and screw couplings in the 20th century, the screw couplings being tightened to leave 2 threads visible on the bottle screw by the shunter, in order to reduce the 'snatching' effect if the coupling became slack and power was picked up too quickly.  Some LNER stock which might appear on cross country services had buckeye type couplings, and these were hinged and could be dropped away to reveal a conventional drawhook; the screw coupling of the adjoining vehicle would be used to couple to the LNER vehicle.  All passenger rated stock with a brake compartment carries a spare screw coupling, painted red.

 

Then there is freight stock rated to run in passenger trains but not classed as NPCCS.  This must be vacuum braked and fitted with screw couplings, and will usually have pneumatic or hydraulic buffers.  Stock originating on the GW would be branded 'XP' denoting the rating, and this was universal in BR days, but I am not able to state that it was used on the Southern in the 30s.  As well as the buffers and screw couplings, a vacuum cylinder will be visible on the underframe, and there will be grease axleboxes, not horsehair.  In the 1930s 10' wheelbase stock of this sort was permitted to run up to 60mph.

 

Bottom of the food chain is freight stock not rated to run in passenger trains.  This will not usually be vacuum fitted, and can have sprung buffers and 3-link couplings.  The bulk of general merchandise vans and opens would still be of this sort in the 30s, and all mineral wagons.  These must not run in passenger trains but can run in 'mixed' trains, which are authorised on some branches by local 'Sectional Appendix' instructions.  The passenger section of the train must be coupled to the loco and have a guard riding in a passenger brake van, and the freight section must have a goods brake at the rear of the train with a goods guard riding in it and displaying side as well as tail lamps.  Mixed trains are described as such in the public timetables, and are allowed longer running times in sections and dwell times at stations, where goods handling or shunting may be required; we are very much in bucolic rural branch territory here! 

 

General merchandise freight stock from the other railways was subject to an RCH sponsored pooling arrangement after 1936, but prior to that date had to be returned to the owning railway, ideally with a payload but empty if that could not be arranged, by the next available service; the goods yards had routing books denoting what that was at any particular time of day.  Post pooling, unfitted vehicles could be loaded anyway or kept on hand without having to be returned to their owning railway, which was still responsible for maintaining them however.  Special purpose vehicles like conflats, shock absorbing vans or opens, cattle wagons and such had to be returned as per the pre 1936 practice, as did any branded 'return to' vehicles.  XP rated stock was not included in the pool and had to be returned.  As a generalisation, non Southern freight stock should be returned to it's owner pre 1936, and unfitted non Southern freight stock with 3-link couplings and sprung buffers can be treated as pool stock after 1936.  Brake vans did not venture beyond the exchange point of their own railway anyway, like locos.

 

As Jason has said, once general merchandise stock was pooled, given that the Southern possessed less of such stock than the other railways, foreign wagons and vans would have been at least as common as the Southern's own, and probably more so, with LMS stock being most prevalent.

Edited March 19, 2020 by The Johnster

[truffy]

Thank you, all, some really useful information here!

 

Maunsell carriages also had buckeye couplings, while older passenger stock was largely screw link.

 

My main confusion was over freight, because I have seen wagons with three-link and brake vans with screw-link. I guess that's because the latter might be found at the end of mixed traffic, as @The Johnster notes.

 

Thanks, once again. Much appreciated!

[jim.snowdon]

1 hour ago, Steamport Southport said:

 

The LMS used them as well.

 

However in the 1930s most wagons were common user so you are just as likely to have a GWR wagon in your train as a SR one.

 

 

 

Jason

I didn't know that - I shall now have to go and peruse my copies of LMS Wagons. And fair point about common user wagons; I had rather hastily read SR as being Southern Railway wagons, not wagons on the Southern Railway .

 

Jim 

[roythebus]

With coaching stock, generally if it had a Pullman style corridor connection it had a buckeye coupling. So did A4 corridor tenders.

 

[jim.snowdon]

7 hours ago, The Johnster said:

Passenger rated stock, that is, passenger carrying vehicles and Non Passenger Carrying Coaching Stock, NPCCS, such as parcels vans always had pneumatic or hydraulic buffers and screw couplings

Screw couplings, yes, but pneumatic or hydraulic buffers, definitely not. The vast majority of such stock, if not all, were fitted with ordinary steel or rubber sprung buffers.

 

7 hours ago, The Johnster said:

Then there is freight stock rated to run in passenger trains but not classed as NPCCS.  This must be vacuum braked and fitted with screw couplings, and will usually have pneumatic or hydraulic buffers.  Stock originating on the GW would be branded 'XP' denoting the rating, and this was universal in BR days, but I am not able to state that it was used on the Southern in the 30s.  As well as the buffers and screw couplings, a vacuum cylinder will be visible on the underframe, and there will be grease axleboxes, not horsehair. 

Again, same comment about the buffers - other than on shock-absorbing wagons, where an early form made its appearance in the 1930s, oleo-pneumatic buffers were essentially unknown on freight stock until the very late 1950s, when BR started fitting them as standard on new builds. And definitely not grease axleboxes (or horsehair ones) - I presume you meant to say oil axleboxes.

 

7 hours ago, The Johnster said:

General merchandise freight stock from the other railways was subject to an RCH sponsored pooling arrangement after 1936, but prior to that date had to be returned to the owning railway, ideally with a payload but empty if that could not be arranged, by the next available service; the goods yards had routing books denoting what that was at any particular time of day.  Post pooling, unfitted vehicles could be loaded anyway or kept on hand without having to be returned to their owning railway, which was still responsible for maintaining them however.  Special purpose vehicles like conflats, shock absorbing vans or opens, cattle wagons and such had to be returned as per the pre 1936 practice, as did any branded 'return to' vehicles.  XP rated stock was not included in the pool and had to be returned.  As a generalisation, non Southern freight stock should be returned to it's owner pre 1936, and unfitted non Southern freight stock with 3-link couplings and sprung buffers can be treated as pool stock after 1936.  Brake vans did not venture beyond the exchange point of their own railway anyway, like locos.

Common User (or pooled) freight stock is a creature of the First World War, although it didn't extend to goods vans until 1919, and then only unfitted examples (which were the majority anyway). Fitted goods vans didn't get included until 1936, and then only those of the LMS, LNER and SR - the GWR kept much of their wagon fleet out of common use until the exigencies of World War Two forced their hand.

 

Jim

[The Stationmaster]

The Southern 1934 General Appendix includes a reference to Instanter couplings on GWR and LMS vehicles and states they must not be used to couple such vehicles to passenger trains, a screw coupling is to be used instead.

 

The XP classification was introduced nationally in the latter half of the 1930s.

 

As a matter of correction the authority to operate a Mixed Train was the Working Timetable (not a Sectional Appendix) for the very obvious reason that staff needed to know which btrains were authorised to run as Mixed Trains.   Although practice might have varied they certainly weren't shwns as Mixed Trains in GWr public timetables and the last (and only) time I travelled on one it was definitely not shown as such in any public timetable information of any sort (Scotland 1970). 

[Wickham Green too]

18 hours ago, jim.snowdon said:

In essence, if it had vacuum brakes, screw couplings would be normal, and every vehicle was fitted with both a hook and a coupling at each end. 

 

Jim

As far as rolling stock's concerned that's correct  -  but you'll see vacuum brakes and three-links on certain Southampton Docks shunters at least : B4 and USA classes ..... not sure about the C14 off hand.

 

( The pedants among us might point out that the correct term is 'screw coupling' ......... you'll not find 'screw link' used by the big railway ! )

Edited March 20, 2020 by Wickham Green too

[The Johnster]

Just to clarify the difference between a mixed train and tail traffic, an XP rated general merchandise van or open with the vacuum brake connected and working can be attached to the rear of a passenger train.  During the 1930s it was I believe limited to 8 axles, 4 vehicles, and the brake continuity test must establish that the brakes are working correctly on the rear 2 vehicles.  A mixed, with a goods brake van at the rear, can carry any traffic, but where it couples to the rear of the passenger stock, the passenger stock's screw coupling must be used to couple the goods vehicle.

 

In fact, where there is any requirement to couple stock with 3-link or instanter couplings to screw coupled passenger rated stock, the screw coupling must be used.  When the loco is coupled to the train, the loco's screw coupling must be used, with the following exceptions; a loco coupled to an unfitted train with 3 link or instanter couplings must use the leading wagon's coupling, a loco with a buckeye coupling attaching to buckeye fitted passenger stock uses the buckeye couplings  (some LNER A3 and A4 pacifics, and trains of 100ton tippler wagons (1970s and later stone and iron ore traffic} have a heavy duty screw coupling on the outer ends of the rake which must be used to couple to the loco.

 

But as a general rule for modelling 1930s SR practice,, and 20th century steam age practice by and large, use the loco screw to attach to the train and use a screw where it is available instead of a 3-link.

 

3 link couplings used on Southampton Docks pilot locos were to cope with sharp curvature and presumably authorised in the Sectional Appendix; passenger trains did not run on running lines outside the dock area with them.  

Edited March 20, 2020 by The Johnster

[Steamport Southport]

5 hours ago, Wickham Green too said:

As far as rolling stock's concerned that's correct  -  but you'll see vacuum brakes and three-links on certain Southampton Docks shunters at least : B4 and USA classes ..... not sure about the C14 off hand.

 

( The pedants among us might point out that the correct term is 'screw coupling' ......... you'll not find 'screw link' used by the big railway ! )

 

It's far easier to use a three link when shunting.

 

If they needed to do a duty which needed vacuum brakes to be connected and/or a screw coupling they would use the one on the stock.

 

 

Jason

[The Stationmaster]

If anybody wants to know all about Mixed Trains and Tail Traffic here's the place to look.      Sorry for going OT.  And note that normally the 3 link coupling (but not an instanter coupling) on the wagon would be used between the passenger vehicles and the wagons of a Mixed Train.

 

 

Edited March 20, 2020 by The Stationmaster