Why do so many trains have incompatible coupling systems?

[O L Leigh]

That is exactly what happened in the Kentish Town incident. The "similar train not very far away" wasn't and took several hours; the coupling adapter procedure fell down; and because of the planned service pattern the train behind was a different coupler and unable to assist even though the recovery procedure was written that it could. Not fluff and nonsense at all to the RAIB in their highly critical report.

Lets put the Kentish Town incident back into it's proper context.

Firstly, the "similar train" was not far away. It was at Hendon. The problem was that there were delays getting it to site due to issues with FCC's incident management and communication issues, uncertainty over the operational behaviour of the trains in certain configurations and the support provided to and by staff on the ground as well as the need for a lengthy wrong direction move. There were other "similar trains" on the southbound line too, but getting these onto the rear of the failed train would have been far too much of an operational faff to make that option work.

Secondly, there were no issues regarding coupling adapters because that rescue option was not selected. However, it could have been made to work if it had been pursued. This is not the same thing as the "...coupling adapter procedure [falling] down". In fact, the relevant adapter had been found by the fitter at Farringdon and arrangements made for the MOM to transport it to site. Your assertion that the following Cl319s were "...unable to assist" is a fiction of your own creation, as the Cl319s would have been perfectly capable of supplying main air to the failed train and pushing it out of the section to a location where it could have been dealt with. That was the reason for the coupling adapter being located.

Thirdly, you're correct to say that the RAIB report was highly critical, but primarily about FCC and it's performance on the day. In fact, coupling, couplers and coupling adapters are not even mentioned in the report's recommendations.

So, fluff and nonsense.

 

[Bevan Price]

I'm sure Triang and Hornby Dublo never had this problem

They did when Hornby Dublo was a 3rd rail system.
And continental HO stock uses different couplings to UK OO stock, even though they will run on the same track.

 

[Taunton]

Lets put the Kentish Town incident back into it's proper context.

I'm afraid to say that does look like some rather thin, if not self-contradictory, excuses, especially once one knows the RAIB report. Which, from the recent Thameslink issue in Copenhagen Tunnel, has not been taken on board at all.

It's notable how many of these issues happen outside 9-5 office hours, when nobody in authority (which nowadays means budget-spending authority) is around.

 

[Whistler40145]

It totally puzzled me that 86s and 87s worked with Mark 1, 2 and 3 stock, but weren't fitted with Buckeye couplings whereas the stock was

 

[O L Leigh]

I'm afraid to say that does look like some rather thin, if not self-contradictory, excuses, especially once one knows the RAIB report.

I’m sorry if that’s how it looks to you, but if you know the RAIB report you will know that it does not criticise the use of coupling adapters nor the incompatible nature of the mixed traction fleet in use on the Thameslink route at that time, which surely is the topic under discussion in this thread.

If you feel that my analysis has been contradictory or fails to follow the RAIB’s findings you’ll need to quote chapter and verse.

 

[Taunton]

It totally puzzled me that 86s and 87s worked with Mark 1, 2 and 3 stock, but weren't fitted with Buckeye couplings whereas the stock was

That was pretty much true of all locomotives. I likewise didn't get why passenger stock got buckeyes (on the old LNER even before nationalisation), including when there was extensive portion dividing and joining, yet the attachment of the locomotive never did.

Likewise, if emus got buckeyes at the ends, on the basis of safety in collisions, why were very simplistic bar couplings allowed within the set. Telescoping in coupled emu collisions seems always within the set, not from one set to the next.

 

[matchmaker]

That was pretty much true of all locomotives. I likewise didn't get why passenger stock got buckeyes (on the old LNER even before nationalisation), including when there was extensive portion dividing and joining, yet the attachment of the locomotive never did.

Likewise, if emus got buckeyes at the ends, on the basis of safety in collisions, why were very simplistic bar couplings allowed within the set. Telescoping in coupled emu collisions seems always within the set, not from one set to the next.

I'm pretty sure that A4s with corridor tenders were fitted with buckeyes at the tender end.

 

[Mat17]

I'm pretty sure that A4s with corridor tenders were fitted with buckeyes at the tender end.

They were.

 

[Taunton]

Was it only the corridor tender A4s that had buckeyes? Gerry Fiennes in "I Tried To Run A Railway" indeed wrote that once one would not couple to the first coach due to a height mismatch, nor could they get the jammed buckeyes apart again - and it was the Royal Train, with 15 minutes to go ... !!!

 

[Mat17]

I'm happy to be corrected by those with more knowledge, but a brief search seems to suggest the corridor tenders were shuffled around between A1, A3 and A4 locos, whether they ALL had buckeye couplings though, that's another question.

 

[grumpyoldman01]

And some of those nightmares only become apparent after a time in use. The Bedford-St Pancras hydraulic DMUs (class 127) were *in theory* fully compatible with other 1st generation units, but a Cravens coupled on the back of one went up in flames thanks to the absence of an audible clue to the driver that it needed to change gear.

I thought the Sandridge incident was caused by a the gearbox on the Cravens class 112 seizing up, and was nothing at all to do with the fact that it was coupled behind a 127.

The driver's desks in the 113s (and I believe also the 127s) looked like those in most mechanical units, and were driven similarly (to mechanical units) when operated in multiple with them; however, when working singly or with another hydraulic, by observation (from the front passenger seat!) they were driven differently - the driver just put the gear selector into "fourth", opened up the throttle, and off they went. After Sandridge, the coupling codes for 127s was changed from Blue Square to Red Triangle, but the trailers reverted to Blue Square after the 127 power cars were withdrawn in the early 1980s

 

[Bill57p9]

I'm happy to be corrected by those with more knowledge, but a brief search seems to suggest the corridor tenders were shuffled around between A1, A3 and A4 locos, whether they ALL had buckeye couplings though, that's another question.

I would expect so as screw link doesn't keep the vehicles close enough for a gangway. Not that crew safety/comfort was a high priority in the 30s...

Always used to bug me when I was a lowlander sleeper regular in the class 90 days that the screw link coupling would be used to give that extra judder when both locomotive and stock had perfectly good buckeyes available...

 

[Mat17]

I thought the Sandridge incident was caused by a the gearbox on the Cravens class 112 seizing up, and was nothing at all to do with the fact that it was coupled behind a 127.

Correct. The gear box seized up, shearing the carden shaft, which then ruptured the fuel tank and the car ignited.

There was another incident the year before at Sough Tunnel, whereby another class 112's carden shaft sheared resulting in the same.

Railcar was the source of the above information.

 

[Roast Veg]

Whenever I see threads like this I'm ever more tempted to build a 'what couples / works with what' spreadsheet. However the research needed would probably take me years!

You can start with the NR document, which is a terse mess.

 

[Mat17]

Which would be the shorter list: what is compatible or what isn't?

 

[matchmaker]

I would expect so as screw link doesn't keep the vehicles close enough for a gangway. Not that crew safety/comfort was a high priority in the 30s...

Always used to bug me when I was a lowlander sleeper regular in the class 90 days that the screw link coupling would be used to give that extra judder when both locomotive and stock had perfectly good buckeyes available...

I'm fairly sure that Pullman gangways require buckeye couplings.

 

[dubscottie]

I'm fairly sure that Pullman gangways require buckeye couplings.

They do. However it was permitted by the LNER to couple two pullman fitted vehicles with a screw coupling and for the gangway to remain in use if one or both the buckeyes were damaged.
Both buckeyes would be lowered, the buffers on one vehicle would be in the long position, the other in the short.
The two vehicles would be shunted together until the gangways compressed and the emergency screw coupling would be tightened as much as possible.
I think it was only to allow staff access and the manoeuvre had to be done on straight track.

 

[TrainTrackJack]

I was at Bangor last Friday to see an E.C.S move of the new 67+MK.IV WAG set, and noticed that the 67 propelling (67010) has a new multiple working socket next to the original AAR one, i guess this is to work with the MK.IV DVT. I take it that all the 67's in the WAWC pool (TfW hire loco's) have been given this modification.

 

[richieb1971]

Forgive the gate crash. But exactly is the maximum load for a coupler? Obviously the coupler behind the locomotive has the most weight behind it. I find it hard to believe in other counties that a mile long train can be pulled by a bulk of metal that is 3 to 6 inches thick.

 

[matchmaker]

They did when Hornby Dublo was a 3rd rail system.
And continental HO stock uses different couplings to UK OO stock, even though they will run on the same track.

Hornby Dublo 2 rail used the same couplings as 3rd rail.

 

[Nym]

I was at Bangor last Friday to see an E.C.S move of the new 67+MK.IV WAG set, and noticed that the 67 propelling (67010) has a new multiple working socket next to the original AAR one, i guess this is to work with the MK.IV DVT. I take it that all the 67's in the WAWC pool (TfW hire loco's) have been given this modification.

Yes, this is to work with the Mk.4Cs

It does still carry AAR, but there are additional signals that wouldn't fit in the 27 way.

 

[ac6000cw]

Forgive the gate crash. But exactly is the maximum load for a coupler? Obviously the coupler behind the locomotive has the most weight behind it. I find it hard to believe in other counties that a mile long train can be pulled by a bulk of metal that is 3 to 6 inches thick.

The 'knuckle' - the moving (and deliberately weakest) part of the standard North American AAR coupler has a maximum tensile (pulling) strength of 2.9MN (650,000 lbf). In compression the coupler body can take 4.0 MN (900,000 lbf).

For comparison, a modern AC-drive US freight diesel loco is capable of about 0.8 MN staring tractive effort, so three of those at the head of a heavy-haul train is about the maximum permissible. Beyond that you need to use 'distributed power' with locos mid and/or end of train to distribute the forces along the train better.

 

[ic31420]

I'd perhaps have more time for Europe had they, of all the things they introduced standards for addressed this issue.

(My other is they should have legislated for standard shapes and sizes in glassware, bottles, jars etc. Then we could simply take our empties back to Tesco for return to manufacturers for refiling rather than smashing them to smitherines, mixing up colours and turning to cullet for reprocessing with huge amounts of energy needed - works for my milk man)