MK4 sets - how fixed are they?

[alexl92]

Unlike loco-hauled MK3 sets, the MK4s have remained in more or less fixed formation throughout their lives. I'm just interested to know to what extent the MK4 sets could be split, mixed and matched or whether there's some equipment which is spread along the train and so each carriage is dependant on the rest of the rake being present to work? Hope that makes sense!

 

[ainsworth74]

They are quite flexible as far as I'm aware. The only significant limitation, I belive, is that you need a TSOE (the coach behind the 91) as that has a coupling that is compatible with locomotives. The couplers between the rest of the coaches are not. I also think you'll need a DVT as that acts as the brake vehicle. (and has a compatible coupling at the pointy end as well).

Otherwise within those constraints I believe you can have whatever formation you desire!

 

[theblackwatch]

Yes they are quite 'normal' - no complexities of the inflexibility of the modern railway! Those who are old enough will remember that when introduced, some of the sets had 2 SV (Service Vehicles) in the formation and additional first class (with only 3 or 4 standards if I recall right) for use on 'Pullman' named trains.

 

[swt_passenger]

Wasn’t it the case that eventually a decision was made to have all trains running at maximum length, and this was basically achieved by not having a full range of spare coaches. Hence whenever a coach failed it was usually just removed for repair, and then returned. So there’s never really been the same sort of day to day re-shuffling of stock between coaching sets, as with say HST Sets...

 

[Dave91131]

Wasn’t it the case that eventually a decision was made to have all trains running at maximum length, and this was basically achieved by not having a full range of spare coaches. Hence whenever a coach failed it was usually just removed for repair, and then returned. So there’s never really been the same sort of day to day re-shuffling of stock between coaching sets, as with say HST Sets...

I think that's basically correct.

The loss of numerous vehicles in the Hatfield and Heck accidents saw a number of vehicle conversions to give 30 full sets, leaving just a spare standard class 'end' vehicle and a spare DVT. Hence if individual vehicles require maintenance over and above the norm this almost always sees sets operating short-formed as there simply isn't the flexibility to shuffle vehicles between sets.

In a nutshell, and in no particular order, the 'Mallard' refurbishment saw the following alterations:

21 open standard vehicles (124xx & 125xx) were converted to open first vehicles (112xx, found next to buffet)

7 open first vehicles retained their original numbers (112xx, found next to buffet)

all remaining open first vehicles were re-numbered to either 113xx (open first disabled, centre of 3 first class vehicles) or 114xx (open first next to DVT with smoking area)

2 buffet vehicles (10314 and 10316) were re-numbered to 11998 and 11999 (open first, found next to buffet like 112xx)

remaining buffet vehicles retained their original numbers (103xx) and had standard class seating fitted to replace first class

1 open standard vehicle (12531) was converted to open standard disabled (12331)

all open standard disabled vehicles (123xx, found next to buffet) retained their original numbers

all remaining open standard vehicles (124xx and 125xx), open standard end vehicles (122xx) and DVT's retained their original numbers, and in the vast majority of cases were extensively shuffled between sets compared to pre-Mallard refurbishment

During the Mallard refurbishments with numerous vehicles stopped, I vividly remember seeing sets in service without a buffet vehicle at all and in one case a buffet vehicle next to the DVT.

Interestingly the ECML HST sets, aside from the addition of an extra standard class vehicle and one or two shuffles due to minor accident damages, remain primarily in their pre-Mallard refurbishment formations to this day.

Pre-Mallard refurbishment something tells me it was 8(?) 'pullman' mk4 sets which had 3 full first class vehicles instead of the usual 2 - I seem to think these were typically used on up London services in the morning peaks, covered Leeds or Newcastle return trips in the day, then formed down London departures in the evening peak.

Happy to be corrected on any of the above - particularly the 'pullman' info.

Hope this helps.

 

[swt_passenger]

I think that's basically correct.

The loss of numerous vehicles in the Hatfield and Heck accidents saw a number of vehicle conversions to give 30 full sets, leaving just a spare standard class 'end' vehicle and a spare DVT. Hence if individual vehicles require maintenance over and above the norm this almost always sees sets operating short-formed as there simply isn't the flexibility to shuffle vehicles between sets...

Thanks for taking the time to provide such a thorough reply.

 

[K.o.R]

They are quite flexible as far as I'm aware. The only significant limitation, I belive, is that you need a TSOE (the coach behind the 91) as that has a coupling that is compatible with locomotives. The couplers between the rest of the coaches are not. I also think you'll need a DVT as that acts as the brake vehicle. (and has a compatible coupling at the pointy end as well).

Otherwise within those constraints I believe you can have whatever formation you desire!

What's special about the 91's rear coupling? In pictures it has buffers, a corridor-style buffing plate and a droppable buckeye coupler. Nothing out of the ordinary at first glance?

 

[ainsworth74]

What's special about the 91's rear coupling? In pictures it has buffers, a corridor-style buffing plate and a droppable buckeye coupler. Nothing out of the ordinary at first glance?

Nothing is unusual about it that's the point!

The issue is with the connections between the Mk4s which are not compatible with conventional locomotive couplings (might be fixed bar but I'm not sure). Hence why locomotives (including 91s) can only couple to one end of the TSOE or the pointy end of the DVT where conventional couplings are fitted.

 

[43096]

Nothing is unusual about it that's the point!

The issue is with the connections between the Mk4s which are not compatible with conventional locomotive couplings (might be fixed bar but I'm not sure). Hence why locomotives (including 91s) can only couple to one end of the TSOE or the pointy end of the DVT where conventional couplings are fitted.

I believe Mark 4s are Tightlock couplers within the set.

 

[ainsworth74]

I believe Mark 4s are Tightlock couplers within the set.

Aha thanks I did a cursory look for info but couldn't quickly lay my hands on it

 

[K.o.R]

This thread confirms that, but why is that a problem? Isn't Tightlock just a buckeye with some extra hardware so that if two come together they have better resistance to vertical motion?

 

[hexagon789]

I think that's basically correct.

The loss of numerous vehicles in the Hatfield and Heck accidents saw a number of vehicle conversions to give 30 full sets, leaving just a spare standard class 'end' vehicle and a spare DVT. Hence if individual vehicles require maintenance over and above the norm this almost always sees sets operating short-formed as there simply isn't the flexibility to shuffle vehicles between sets.

In a nutshell, and in no particular order, the 'Mallard' refurbishment saw the following alterations:

21 open standard vehicles (124xx & 125xx) were converted to open first vehicles (112xx, found next to buffet)

7 open first vehicles retained their original numbers (112xx, found next to buffet)

all remaining open first vehicles were re-numbered to either 113xx (open first disabled, centre of 3 first class vehicles) or 114xx (open first next to DVT with smoking area)

2 buffet vehicles (10314 and 10316) were re-numbered to 11998 and 11999 (open first, found next to buffet like 112xx)

remaining buffet vehicles retained their original numbers (103xx) and had standard class seating fitted to replace first class

1 open standard vehicle (12531) was converted to open standard disabled (12331)

all open standard disabled vehicles (123xx, found next to buffet) retained their original numbers

all remaining open standard vehicles (124xx and 125xx), open standard end vehicles (122xx) and DVT's retained their original numbers, and in the vast majority of cases were extensively shuffled between sets compared to pre-Mallard refurbishment

During the Mallard refurbishments with numerous vehicles stopped, I vividly remember seeing sets in service without a buffet vehicle at all and in one case a buffet vehicle next to the DVT.

Interestingly the ECML HST sets, aside from the addition of an extra standard class vehicle and one or two shuffles due to minor accident damages, remain primarily in their pre-Mallard refurbishment formations to this day.

Pre-Mallard refurbishment something tells me it was 8(?) 'pullman' mk4 sets which had 3 full first class vehicles instead of the usual 2 - I seem to think these were typically used on up London services in the morning peaks, covered Leeds or Newcastle return trips in the day, then formed down London departures in the evening peak.

Happy to be corrected on any of the above - particularly the 'pullman' info.

Hope this helps.

As the sets were introduced under BR there were a number of 'ad hoc' formations as vehicles became available. Eventually I believe that BR operated the following formations with 3 sets being Pullman:

Standard formation:
TSOE-TO-TO-TO-TOD-SV-PO-PO-DVT

Pullman formation:
TSOE-TO-TO-TOD-SV-PO-PO-SV-PO-DVT

I believe GNER ammended the Pullman sets to have only one SV pre-Mallard refurbishment:

TSOE-TO-TO-TOD-SV-PO-PO-PO-DVT

Post-Mallard you then have the current formation for all sets of:

TSOE-TO-TO-TO-TOD-SV-PO-POD-PO-DVT

I believe Mark 4s are Tightlock couplers within the set.

Yes, tighlock within set and the TSOE has a buckeye at the non-gangwayed end.

This thread confirms that, but why is that a problem? Isn't Tightlock just a buckeye with some extra hardware so that if two come together they have better resistance to vertical motion?

The buckeye still allows an amount of slack whereas I believe the tighlock removes the slack. Certainly if you've sat in Coach B on a Mk4 set you can feel when the loco powers or shuts off!

 

[whhistle]

Has a 91 ever pulled a rake pointy end first?
When ever I've seen a 91 rescue another set, it always seems to be blunt end leading, so just wondered if there was a reason for that.

 

[sprinterguy]

Has a 91 ever pulled a rake pointy end first?
When ever I've seen a 91 rescue another set, it always seems to be blunt end leading, so just wondered if there was a reason for that.

It's not unknown for a class 91 to lead a full rake pointy end first with another class member dead in train behind the assisting loco. Here's an example (Not my photo):
https://farm5.static.flickr.com/4838/45365584105_95278ffd35_b.jpg

There's even been at least one instance of a class 91 assisting an HST in this manner.

The most common reason for running a 225 set out of it's regular formation is due to a fault with the DVT, in which case the class 91 will almost always be blunt end first when coupled directly to the DVT as the 91s are usually north facing.

 

[delt1c]

would be interesting to see a 91 on a railtour with a rake of Mk1's or Mk's II's. To the best of my knowledge they have never operated in passenger service with anything other than MkIV stock, or as when 1st built with an HST rake where a converted HST power car was converted for use as a DVT

 

[43096]

would be interesting to see a 91 on a railtour with a rake of Mk1's or Mk's II's. To the best of my knowledge they have never operated in passenger service with anything other than MkIV stock, or as when 1st built with an HST rake where a converted HST power car was converted for use as a DVT

When new they did work charters occasionally on Mark 1 stock, and there was at least one instance of them working a mail van train.

 

[ainsworth74]

91s have definetly hauled Mk1s or Mk2s. I've seen a photo of I think it was a staff special formed of that sort of stock hauled by a 91.

 

[delt1c]

would love to some photos of these , must look strange

 

[_toommm_]

would love to some photos of these , must look strange

There's a video here of a 91 running blunt end first with a rake of MK1 and MK2 coaches:

 

[hexagon789]

91s have definetly hauled Mk1s or Mk2s. I've seen a photo of I think it was a staff special formed of that sort of stock hauled by a 91.

They did haul service trains of Mk2s in the early days.

 

[Highlandspring]

This thread confirms that, but why is that a problem? Isn't Tightlock just a buckeye with some extra hardware so that if two come together they have better resistance to vertical motion?

Pretty much but the original BR Intercity 225 User Guide suggests the coach gangways would be damaged if an attempt is made to couple a buckeye to the tightlock -

 

[delt1c]

There's a video here of a 91 running blunt end first with a rake of MK1 and MK2 coaches:

Now with that yellow end, the 91 looks like Mr Angry , so if a 35 and a blunt end 91 were on the blocks at the Cross it would be Mr Smiley meets Mr Angry

 

[507 001]

Apparently in the late 80s there was a regular booked working for a 91 to take an ex Hull train from Doncaster.

Link

 

[Bringback309s]

Go to 2:40

and 7:58 in this one:

At 10:20 a 91 on the fantastic looking charter set!

 

[jopsuk]

Under normal circumstances, if a second 91 is hauling a "dead" set north, it'll do so pointy end first (with the locos coupled pinty-to-blunt), if south then it'll be blunt end first (pointy end of DVT to pointy end of loco)

 

[hexagon789]

Pretty much but the original BR Intercity 225 User Guide suggests the coach gangways would be damaged if an attempt is made to couple a buckeye to the tightlock -

View attachment 64387

View attachment 64386

Would it perhaps be that with an ordinary buckeye, the gangway takes the compressive forces with the couplers only the pulling force but Tightlocks take both forces and thus the gangways on Mk4s aren't designed to take compressive forces in the same way and therefore coupling buckeye to tightlock could damage the gangway because it would be compressed and potentially damaged?

 

[Highlandspring]

Would it perhaps be that with an ordinary buckeye, the gangway takes the compressive forces with the couplers only the pulling force but Tightlocks take both forces and thus the gangways on Mk4s aren't designed to take compressive forces in the same way and therefore coupling buckeye to tightlock could damage the gangway because it would be compressed and potentially damaged?

I think you’ve likely hit the nail on the head there.

 

[hexagon789]

I think you’ve likely hit the nail on the head there.

It was an educated guess really but I think it makes sense.

 

[dubscottie]

You are correct. When originally ordered, the Mk4 was supposed to have conventional buffers/drop-head buckeyes and Mk3 style gangways.

BR then decided to use sealed gangways which needed Tightlock couplers (and dampers on the drawbars - fitted later) as sealed gangways cant take compression or sideways forces.

All Mk4 passenger stock (not sure about the DVT) have have holes on the buffer beam for buffers and a Pullman rubbing plate.

They could, in theory, be fitted with buffers, hook & buckeye etc still but would need new Mk 2-3 style gangways.

 

[hexagon789]

You are correct. When originally ordered, the Mk4 was supposed to have conventional buffers/drop-head buckeyes and Mk3 style gangways.

BR then decided to use sealed gangways which needed Tightlock couplers (and dampers on the drawbars - fitted later) as sealed gangways cant take compression or sideways forces.

All Mk4 passenger stock (not sure about the DVT) have have holes on the buffer beam for buffers and a Pullman rubbing plate.

They could, in theory, be fitted with buffers, hook & buckeye etc still but would need new Mk 2-3 style gangways.

The gangways are much better than the Mk3 ones which quite often leak. I wonder if the sealed gangway was decided upon when BR decided to have the Mk4s designed as being capable of having tilt retrofitted.