Class 455 & 456 - Why pipes and jumpers?

[Class455]

I've often wondered recently why the Class 455's (and subsequently the Class 456's) use pipes and jumpers when coupling instead of automatic tightlock couplers? Especially when you consider that the technology for simpler coupling existed from the late 1970's and feature on similar aged EMU's such as the Class 317 and 319, and even their predecessors on the South Western Region, the Class 508's.
Whilst attaching and detaching a pair of Class 455's doesn't take much longer than a 377 for example, when you also think of the benefits of automatic tightlock couplers had over pipes and jumpers it does make me wonder why BR's engineers back in 1982 decided to fit the 455's with the latter when designing them. For a start, the Class 456's were supposed to have a similar front end to the Class 321's, but ultimately needed a completely different front end design to accommodate the pipes and jumpers required to work with Class 455's.Also, with the benefit of hindsight, 455's could have worked in multiple with different units both in service and in emergency situations, such as Class 319's when they were with Connex South Central/Southern, and could have worked with the likes of Class 375's before they were fitted with Dellner couplers and Networkers.

You also wonder how much time this would have saved during the overall attachment and detachment process for the 455's, especially as station staff needed to learn how to attach/remove the pipes and jumper couplers, whereas for example it's far easier to split and attach trains with automatic tightlock couplers as staff would have just needed to guide the driver to couple up to the unit in front and then ease up and pull away. I think I'm right in saying that if the 455's came with automatic tightlock couplers, the competency to split and attach them would have been the same as 377's and 450's, therefore knowledge wouldn't be lost in certain locations. And the electrical connection would have been made simply by pressing a "couple" button in the cab rather than needing to have jumper cables plugged together.

I did wonder if the reason was because it was a traditional Southern region thing to have, considering the 455's were being introduced around Slammers which used pipes and jumpers, but this wasn't the case with the 508's and units that followed just a few years later like the 319's which were fitted with automatic couplers. So was there actually a specific reason behind why 455's used pipes and jumpers?

 

[XAM2175]

I did wonder if the reason was because it was a traditional Southern region thing to have, considering the 455's were being introduced around Slammers which used pipes and jumpers, but this wasn't the case with the 508's and units that followed just a few years later like the 319's which were fitted with automatic couplers. So was there actually a specific reason behind why 455's used pipes and jumpers?

It's been mentioned here before a few times over the years. IIRC there were doubts about the reliability of the automatic connectors, which weren't helped by experiences with trying to couple 508 sets on tightly-curved track.

 

[Islineclear3_1]

Probably for ease of coupling to a locomotive to/from works or a depot pilot and these were a well-established and reliable design. The Southern was also desperate for new stock at the time.

 

[Ken H]

Think it was a bit of 'staying with what you know' from the southern region.
But surely there is a risk that someone uncouples, but does not disconnect the jumpers, and the front is ripped of a unit.

 

[Surreytraveller]

They do have automatic tightlock couplers. But pipes and jumpers for the electrics and air.
You wouldn't have been able to couple one to a 375, as the software wouldn't be compatible

 

[Intercity110]

I remember reading somewhere that it was to enable them to MU work with older SR EMUs in an emergency. Looks quite nice though.

 

[Ken H]

I remember reading somewhere that it was to enable them to MU work with older SR EMUs in an emergency. Looks quite nice though.

I suspect not multiple. But you could connect the air brake hoses.

 

[43096]

I suspect not multiple. But you could connect the air brake hoses.

Definitely not multiple. They're different jumper plugs/sockets for a start.

 

[Bald Rick]

They do have automatic tightlock couplers. But pipes and jumpers for the electrics and air.
You wouldn't have been able to couple one to a 375, as the software wouldn't be compatible

difficult to have compatible software when one part of the equation doesn’t have any!

 

[Class455]

They do have automatic tightlock couplers. But pipes and jumpers for the electrics and air.
You wouldn't have been able to couple one to a 375, as the software wouldn't be compatible

Not even in an emergency?

 

[Dr_Paul]

It's been mentioned here before a few times over the years. IIRC there were doubts about the reliability of the automatic connectors, which weren't helped by experiences with trying to couple 508 sets on tightly-curved track.

I'm pretty sure that I read something to this effect, a long time back. I believe that there were problems with the couplers on the PEP sets as well as the 508s. I've just had a look at Colin Marsden's Southern Electric Multiple Units 1948–1983, but he doesn't say why the 455s had pipes and jumpers.

 

[XAM2175]

Not even in an emergency?

You can mechanically couple any two Tightlock couplers together in an emergency, yes, but that would be it.

 

[WarrenTManager]

On the 15x fleet at Salisbury, the inter-car BSI couplings were changed to bar and jumper/pipe to reduce the number of TINs that were incurred from loss of continuity between the BSI coupler boxes. It did the industry a favour as it boosted the float of end couplers and saved a load of grief. There was a specially made bar to BSI coupling adaptor for shunting purposes eg pushing or pulling a dead car or 58 car onto the single coach length lift shop using a good unit as a depot horse.

With the 455s (and 456s) you also only needed to jumper one side eg 5848 male connects to 5849 female. If that cable or jumper goes wrong, you can swap sides and connect to opposite side female to male. Whereas with the 508 if one of the electrical heads has an issue, game over.

 

[D7666]

Thanks that is interesting on the SW 15x fleet inter car couplers. Not heard that before.

Pedant that I am, may I ask if that applies to the whole lot - all of the 3car 159/0s and 159/1s, and the 2car 158s ? And could you give an approximate date please ?

 

[WarrenTManager]

Thanks that is interesting on the SW 15x fleet inter car couplers. Not heard that before.

Pedant that I am, may I ask if that applies to the whole lot - all of the 3car 159/0s and 159/1s, and the 2car 158s ? And could you give an approximate date please ?

All Salisbury inter-car couplings are bar. Circa 2013. As I say it helped out the national float to help cover for couplers written off over the years through enthusiastic coupling, trees etc

 

[61653 HTAFC]

All Salisbury inter-car couplings are bar. Circa 2013. As I say it helped out the national float to help cover for couplers written off over the years through enthusiastic coupling, trees etc

I recall reading somewhere that some of the other Sprinter classes have bars rather than autocouplers within sets. Not all sets though, as there was an incident a few years back where a 150 set decoupled itself in Leeds station throat.

 

[Efini92]

On the 15x fleet at Salisbury, the inter-car BSI couplings were changed to bar and jumper/pipe to reduce the number of TINs that were incurred from loss of continuity between the BSI coupler boxes. It did the industry a favour as it boosted the float of end couplers and saved a load of grief. There was a specially made bar to BSI coupling adaptor for shunting purposes eg pushing or pulling a dead car or 58 car onto the single coach length lift shop using a good unit as a depot horse.

With the 455s (and 456s) you also only needed to jumper one side eg 5848 male connects to 5849 female. If that cable or jumper goes wrong, you can swap sides and connect to opposite side female to male. Whereas with the 508 if one of the electrical heads has an issue, game over.

The sprinters had electrical boxes on the inner vehicle couplers?

 

[D7666]

All Salisbury inter-car couplings are bar. Circa 2013. As I say it helped out the national float to help cover for couplers written off over the years through enthusiastic coupling, trees etc

Thanks. Muchos obrigados.

 

[XAM2175]

I recall reading somewhere that some of the other Sprinter classes have bars rather than autocouplers within sets. Not all sets though, as there was an incident a few years back where a 150 set decoupled itself in Leeds station throat.

According to BR's vehicle diagrams in the mid-'80s:

• 150/0 units (including the one that was a 154 for a while) had bar couplings between vehicles;
• 150/1 and 150/2 units had BSI mechanical couplings with jumper cables between vehicles;
• 155 units had bar couplings between vehicles, and;
• 156 units had full BSI autocouplers between vehicles.

 

[Ken H]

According to BR's vehicle diagrams in the mid-'80s:

• 150/0 units (including the one that was a 154 for a while) had bar couplings between vehicles;
• 150/1 and 150/2 units had BSI mechanical couplings with jumper cables between vehicles;
• 155 units had bar couplings between vehicles, and;
• 156 units had full BSI autocouplers between vehicles.

Which is how they made 3 car 150's by sandwiching a 150/2 between two 150/1 vehicles.
And how, when the 158's came in, they were able to make 'tadpole' 158/156 two car units. The tread brakes on the 156 meant the wheel treads on that vehicle were kept clean so operated track circuits reliably, while they developed a track circuit assister to fit to 158's.