Blunt end first on Class 91

[TurbostarFan]

Does anyone know why the Class 91 is sometimes run blunt end first?

 

[Intermodal]

Yep, they run it blunt end first when the pointy end is facing towards attached coaches and the blunt end isn't.

 

[Cowley]

Hm. I think there may have been a thread or two on this before.

 

[mrdon]

Google it and a link comes up from this forum, it’s been discussed already. Posted the link but seems to be awaiting approval.

 

[MCSHF007]

Frequently puzzled why people who have been members of this forum for a couple of years or more (and are therefore presumably not newcomers to 'the railway') ask this sort of question. But then what do I know?

 

[driver_m]

The most obvious one will be because of a DVT failure preventing the driver taking it from that end and a need for the loco to be run round. We had to do that with WC stock in our DVT days regularly. No need for the snidey responses to the question. What's obvious to many isn't to others .

 

[whhistle]

Yep, they run it blunt end first when the pointy end is facing towards attached coaches and the blunt end isn't.

Another reason could be some sort of failure in the "normal" cab, like a wiper fault, horn fault, seat broken... anything really.

 

[AlistairCowell]

There was a service recently which involved in blunt-end first:

 

[trebor79]

Must be a right pain to sort out once it gets to kings cross. I guess another loco needs to drag the while lot to Bounds Great for the loco to run round.

 

[trainmania100]

Must be a right pain to sort out once it gets to kings cross. I guess another loco needs to drag the while lot to Bounds Great for the loco to run round.

Sometimes there's a 67 thunderbird parked at kings cross maybe for this sort of thing

 

[DarloRich]

There was a service recently which involved in blunt-end first:

It is hardly an unprecedented event

 

[Tim R-T-C]

Last one I saw, the wipers on the DVT had failed, so a 91 was summoned to be the London-end driving cab.

As the 91s all face the same direction, unless they run around the loop at Newcastle, it was blunt end first.


91105 prepares to depart Leeds, blunt end first by Timothy Young, on Flickr

 

[hexagon789]

Does anyone know why the Class 91 is sometimes run blunt end first?

TDM (Time Division Multiplex) fault, meaning the push-pull equipment isn't working so the driver can't drive from the DVT with the 91 propelling so it has to be done 'old school' with the 91 running-round to couple at the opposite end.

Originally they were going to work Sleeping Car trains as well, which would've seen them frequently running blunt-end first, though they never ended up working such services.

They are limited to 110mph when running blunt-end first as well.

 

[LOL The Irony]

They are limited to 110mph when running blunt-end first as well.

Is that due to aerodynamics or the fact that they weren't intended to go 125 or 140 blunt end first?

 

[trebor79]

Aerodynamics on the pantograph knuckle putting too much load onto the OHL.

 

[delticdave]

Aerodynamics on the pantograph knuckle putting too much load onto the OHL.

Q?. Wasn't there a programme to refit the 91's with a 2nd pantograph?

ISTR that there are photographs of such a device (really 2 pantos on one frame) in a magazine

.

 

[43096]

Q?. Wasn't there a programme to refit the 91's with a 2nd pantograph?

ISTR that there are photographs of such a device (really 2 pantos on one frame) in a magazine

.

I think it was 91114 had that mod done as a trial fit. It was decided it wasn't worthwhile, so I think it has reverted to a standard pantograph, though it retains the cab roof modifications.

 

[hexagon789]

Is that due to aerodynamics or the fact that they weren't intended to go 125 or 140 blunt end first?

I believe aerodynamics are the main reason, yes. They would only have run at a max of 100, normally 80mph, if they had ended up working sleepers anyway.

 

[Ben Bow]

Whilst its not that rare to see a 91 with the pointy end coupled to the coaches, don't remember ever seeing a DVT the same.

 

[GusB]

Whilst its not that rare to see a 91 with the pointy end coupled to the coaches, don't remember ever seeing a DVT the same.

The DVT only has one driving cab, isn't powered* and is supposed to remain coupled to the rest of the set, so there'd be no point in putting it blunt end first!

*There is one monstrosity Mk3 DVT which does have a driving cab at the blunt end, but that's another thread

 

[ash39]

Aerodynamics on the pantograph knuckle putting too much load onto the OHL.

Why is this not an issue when running in normal formation with the DVT leading? Does the airflow around the coaches create a slipstream for the pan?

 

[43096]

Whilst its not that rare to see a 91 with the pointy end coupled to the coaches, don't remember ever seeing a DVT the same.

The Mark 4s have Tightlock couplers within the set, so the only vehicles that can be coupled to normally are the outer ends of the DVT (pointy end) and the TSOE (end with no gangway).