GW goods vans 1939 fitted with screw couplings

[GWR_Modeller]

Hi,

I am reading a series of articles in GWRJ about goods vans.  One part of the series mentions the V23 diagram of 12t vacuum fitted Van's built between 1934 and 1941  There were about 4000 of these.  In 1938 and 1939 1197 were, the article records, completed with screw couplings rather than normal goods van fittings.  At the same time the V24 diagram of unfitted vans was being built.  So there are three concurrent van types being built ie unfitted, fitted with 3 link couplings and fitted with screw couplings.  How did the use of the screw coupling fitted vans differ from the other vacuum fitted goods vans?

Regards,

Paul

[Miss Prism]

Longer buffers.

 

[GWR_Modeller]

Yes those as well but for what purpose?

[Miss Prism]

When coupled in 'long-mode', instanters gave 7" between faces of 18" buffers, but when the instanters were changed to 'close-coupled', there was about 1.75" between buffer faces, i.e. there was still some banging about between vehicles when accelerating and decelerating.

 

Screw couplings, always associated with 20.5" buffers, could be wound up to get buffer faces touching, thus minimising untoward vehicle behaviour.

 

 

 

[GWR_Modeller]

Vacuum freights had been running for 30 years plus with fitted stock and instanter couplings.  So did the fitted goods vans with screw couplings, and long buffers, in large numbers, serve a new class of train or type of traffic?  

[Miss Prism]

In  a word, yes - express freights, the majority of which ran at night, and typically 60 to 70 wagons. With screw couplings wound up, they needed big locos to get them rolling and up to schedule. 

 

 

Edited November 28, 2020 by Miss Prism

[GWR_Modeller]

There do not seem to have been earlier large batches of ordinary goods van with these fittings.  Meat vans, cattle wagons, the few Mink Fs but others?  So over a thousand 12t vans in a short period seems to be a specific decision rather than routine addition.

[Paul H Vigor]

Would fitted vans required to run in passenger trains be equipped with screw couplings?

[Miss Prism]

51 minutes ago, Paul H Vigor said:

Would fitted vans required to run in passenger trains be equipped with screw couplings?

 

Yes.

[GWR_Modeller]

Goods vans wouldn't run in a passenger train would they?

[Miss Prism]

52 minutes ago, GWR_Modeller said:

So over a thousand 12t vans in a short period seems to be a specific decision rather than routine addition.

 

Certainly.

 

Some bedtime reading:

[The Stationmaster]

12 hours ago, Paul H Vigor said:

Would fitted vans required to run in passenger trains be equipped with screw couplings?

 

11 hours ago, Miss Prism said:

 

Yes.

The correct answer is 'no'.    The vehicle, provided that it met the conditions which allowed it to be attached to a passenger train, did not need to have a screw coupling but it had to be coupled to the train by means of a screw coupling - using the emergency screw coupling.   And if you want to be very pedantic in your detailing said coupling was painted red, not black.

[Fat Controller]

13 hours ago, GWR_Modeller said:

Goods vans wouldn't run in a passenger train would they?

They frequently did, well into BR days. Even when loco-hauled trains were supplanted by DMMUs, it was not uncommon to see one or two 12t vans attached to the tail. In the late 1960s/ early 1970s, my school overlooked the Swansea- Fishguard main line; just after 11:00 every day, there would be a Swansea-bound train with a van or two as tail traffic. I even saw a photo of a Milford- Swansea train with a 5-plank 'Pipe' wagon at the end. 

[Paul H Vigor]

13 hours ago, GWR_Modeller said:

Goods vans wouldn't run in a passenger train would they?

If they were fitted they could. The tightened screw coupling would reduce the 'snatch' when the train started to move? Mixed passenger and goods trains were often features of GW branchline working.

[The Stationmaster]

3 hours ago, Paul H Vigor said:

If they were fitted they could. The tightened screw coupling would reduce the 'snatch' when the train started to move? Mixed passenger and goods trains were often features of GW branchline working.

Mixed Trains were very different of course because the wagons could be coupled to each other with ordinary 3 link couplings or indeed whatever coupling they were equipped with.  A wagon with 3 link couplings could be coupled to the coaching stock using the 3 link coupling but if the wagon had screw couplings the emergency screw coupling had to be used to couple it to the coaching stock.

 

As far as attaching freihght vehicles to passenger trains as tail traffic was concerned things changed over the years.  the XP marking came into use on in the 1930s and any vehicle bearing an XP marking could be attached to a passenger train although from the early 1960s onwards there were progressively stricter limitations on speed of 6 and 4 wheel vehicles which gradually ruled them out from being attached even to those passengers trains still authorised to convey 4 wheeled vehicles.

[GWR_Modeller]

 Just to be certain I understand correctly....

Coaches and wagons all had couplings both ends.  So to connect a pair of railway vehicles together only one of the couplings between them had to be used and the other was surplus at that specific time?

 

In the case where one vehicle had a screw coupling/longer buffers and the other had a three link/instanter then only the latter could be used? Either that or the emergency screw coupling?

 

In that case the 1000 plus 12t goods vans manufactured with screw couplings/longer buffers (see first post) would have to be managed carefully to marshal them into trains altogether because if not then mixing them into a vacuum train with the other vans having three link/instanter fittings would negate any advantage of the diferent fittings.  Is that a reasonable supposition?  How would that work if they left GWR area?  Do you think they were NCU?

[The Stationmaster]

4 hours ago, GWR_Modeller said:

 Just to be certain I understand correctly....

Coaches and wagons all had couplings both ends.  So to connect a pair of railway vehicles together only one of the couplings between them had to be used and the other was surplus at that specific time?

 

In the case where one vehicle had a screw coupling/longer buffers and the other had a three link/instanter then only the latter could be used? Either that or the emergency screw coupling?

 

In that case the 1000 plus 12t goods vans manufactured with screw couplings/longer buffers (see first post) would have to be managed carefully to marshal them into trains altogether because if not then mixing them into a vacuum train with the other vans having three link/instanter fittings would negate any advantage of the diferent fittings.  Is that a reasonable supposition?  How would that work if they left GWR area?  Do you think they were NCU?

It was a bit more complicated than that.

 

Attaching a freight vehicle to a passenger train, even if it had screw couplings, the emergency screw coupling had to be used (because it was the right length for use w with passenger stock buffers).  However in the case of Instanter fitted vehicles the wording was rather ambiguous saying they could be coupled to passenger vehicles but not which sort of coupling had to be used

 

But when attaching a freight vehicle to the passenger vehicles in Mixed Train the wagon 3 link, including Instanter, coupling was to be used.

 

As far as vehicles in freight trains were concerned the Instructions were not only different but changed over the years.  

The original 1936 instruction required that screw couplings on freight vehicles in the unfitted portion of  freight trains were only to be used when both vehicles had screw couplings.  If the adjacent vehicle did not have a screw coupling its coupling was to be used to couple that wagon to the vehicle fitted with a screw coupling.  

This Instruction was revised and amplified in December 1937 and then said if the adjacent vehicle had an instanter coupling it was to be used irrespective of the vehicles being, or not being, in the fitted portion of a freight train. If the other vehicle had an ordinary 3 link shackle the screw coupling was to be used in the fitted portion and the 3 link coupling in the unfitted portion. At that time the original relaxation of in extremis using the screw coupling if the other type of coupling didn't reach was discontinued.

The Instruction was further revised in February 1939 and while I can't get at all of it what appears to have changed is that the relaxation to permit use of a screw coupling in extremis when the other coupling was too short, was reintroduced with caveats regarding teh maintenance condition of the screw coupling particularly to enusre that it was well oiled and worked flivbly in order to avoid the risk of it jumping off a coupling hook.

The Instruction was amended and reissued in October 1948 (probably to bring all BR Regions into a common situation) and from then the screw coupling was always to be used in fitted portions and not to be used in the unfitted portion unless it was between two adjacent screw coupled vehicles.  The in extremis situation remained although the wording was slightly altered.

 

It might help to understand a bit more about the behaviour of couplings in certain situations and the safety risks that came with different types.  A screw coupling of those days was not designed for very heavy loading whereas 3 link and Instanter couplings were.  Thus if used in the wrong way a screw coupling could be damaged by traction shocks as a train was 'picked up' from a start with the wagons buffered  up.  Plus unless the coupling was in tip top condition it might not flex properly at the intermediate joints and could jump off a coupling hook.  In a fitted train the effect of traction etc shocks was reduced because the distance between buffer faces was far less than  with an Instanter in the short position and much less than a 3 link coupling.  

 

Screw couplings were also a downright nuisance, and presented some safety hazards to staff, when used on freight vehicles as it meant that someone had to go in between (adjacent vehicles) to either tighten or slacken the screw when preparing trains or getting vehicles ready to shunt. - and of course they cost more than other couplings.  In stark contrast to that the only time anyone needed to go in between with an Instanter coupled vacuum braked wagon was when bagging up the vac pipes during train preparation thereby reducing by 50% the frequency of potentially risking a member of staff to severe injury or death.

[57xx]

21 hours ago, The Stationmaster said:

It was a bit more complicated than that.

 

Attaching a freight vehicle to a passenger train, even if it had screw couplings, the emergency screw coupling had to be used (because it was the right length for use w with passenger stock buffers).  However in the case of Instanter fitted vehicles the wording was rather ambiguous saying they could be coupled to passenger vehicles but not which sort of coupling had to be used

 

But when attaching a freight vehicle to the passenger vehicles in Mixed Train the wagon 3 link, including Instanter, coupling was to be used.

 

As far as vehicles in freight trains were concerned the Instructions were not only different but changed over the years.  

The original 1936 instruction required that screw couplings on freight vehicles in the unfitted portion of  freight trains were only to be used when both vehicles had screw couplings.  If the adjacent vehicle did not have a screw coupling its coupling was to be used to couple that wagon to the vehicle fitted with a screw coupling.  

This Instruction was revised and amplified in December 1937 and then said if the adjacent vehicle had an instanter coupling it was to be used irrespective of the vehicles being, or not being, in the fitted portion of a freight train. If the other vehicle had an ordinary 3 link shackle the screw coupling was to be used in the fitted portion and the 3 link coupling in the unfitted portion. At that time the original relaxation of in extremis using the screw coupling if the other type of coupling didn't reach was discontinued.

The Instruction was further revised in February 1939 and while I can't get at all of it what appears to have changed is that the relaxation to permit use of a screw coupling in extremis when the other coupling was too short, was reintroduced with caveats regarding teh maintenance condition of the screw coupling particularly to enusre that it was well oiled and worked flivbly in order to avoid the risk of it jumping off a coupling hook.

The Instruction was amended and reissued in October 1948 (probably to bring all BR Regions into a common situation) and from then the screw coupling was always to be used in fitted portions and not to be used in the unfitted portion unless it was between two adjacent screw coupled vehicles.  The in extremis situation remained although the wording was slightly altered.

 

It might help to understand a bit more about the behaviour of couplings in certain situations and the safety risks that came with different types.  A screw coupling of those days was not designed for very heavy loading whereas 3 link and Instanter couplings were.  Thus if used in the wrong way a screw coupling could be damaged by traction shocks as a train was 'picked up' from a start with the wagons buffered  up.  Plus unless the coupling was in tip top condition it might not flex properly at the intermediate joints and could jump off a coupling hook.  In a fitted train the effect of traction etc shocks was reduced because the distance between buffer faces was far less than  with an Instanter in the short position and much less than a 3 link coupling.  

 

Screw couplings were also a downright nuisance, and presented some safety hazards to staff, when used on freight vehicles as it meant that someone had to go in between (adjacent vehicles) to either tighten or slacken the screw when preparing trains or getting vehicles ready to shunt. - and of course they cost more than other couplings.  In stark contrast to that the only time anyone needed to go in between with an Instanter coupled vacuum braked wagon was when bagging up the vac pipes during train preparation thereby reducing by 50% the frequency of potentially risking a member of staff to severe injury or death.