Mk III / Mk IV Compatibility

[MrC]

The Mk3's (or even the Mk4 as it would prob be easier to modify) would need major alterations to the drawbar and gangways. The centre couplers on a Mk3 can only take tension forces and not compression (hence the use of buffing plate) whereas the Tightlock couplers on a Mk4 take all the forces.

And then to further mix things up there's the Mk.3 coaches used to make up a Cl.442

Power operated doors, 3-phase electrics, bar-coupled between coaches (drophead buckeye between units), SR EP/triple-valve brake system, SR MU system, etc

 

[ChrisCooper]

442s though can be hauled by any loco. They have drophead buckeyes and buffers, low level air connections and standard ETS sockets. Although they are 3 phase, this will be from an MA set which can run off either the 750v third rail supply or the 1000v ETS from a loco. Hauled Mk3s and air-conditioned Mk2s also use 3 phase electrics, again using MA sets powered by the locos ETS (the former GX Mk2s were also modified to run off 750v).

 

[E&W Lucas]

HST's are operated under loco hauled rules.

 

[ralphchadkirk]

HST's are operated under loco hauled rules.

Yes, you're right. My mistake. The Rule Book still refers to them as class 253/4 though.

 

[dubscottie]

158/9

Close.. Number-wise anyway. This one has a Steel body.

 

[MrC]

442s though can be hauled by any loco. They have drophead buckeyes and buffers, low level air connections and standard ETS sockets. Although they are 3 phase, this will be from an MA set which can run off either the 750v third rail supply or the 1000v ETS from a loco. Hauled Mk3s and air-conditioned Mk2s also use 3 phase electrics, again using MA sets powered by the locos ETS (the former GX Mk2s were also modified to run off 750v).

Not quite. 442 Mk.3s don't use MA sets, they use a converter and they were found not to work too well when fed from a loco ETS supply so the ETS feed was disabled years ago.

And although they can be hauled by a loco, you probably wouldn't want to use disc braked triple-valved passenger stock these days

 

[Helvellyn]

I don't think the HST was designed 'as a DEMU' but they were incorrectly classified as such for a while.

So BR incorrectly classified the fleet when they introduced them? If so why is this the case: -

• Class 251 were the Blue Pullmans.
• Class 252 was the prototype HST
• Class 253 were the WR 2+7 HSTs (and later the NE/SW 2+7 sets)
• Class 254 were the ER 2+8 HSTs (which were originally intended to have the power car engines set at a higher rating).

All vehicles were numbered in a number series to keep them together: -

• 400xx Trailer Buffet Second (later 404xx Trailer Buffet Standard)
• 403xx Trailer Buffet Unclassified (later 407xx Trailer Buffet First)
• 405xx Trailer Kitchen Unclassified
• 41xxx Trailer Frst
• 42xxx Trailer Second (later Trailer Standard)
• 43xxx Driving Motor Brake
• 44xxx Trailer Guard Second (later Trailer Guard Standard)

The power cars were built under lot numbers, as Driving Motor Brakes. When the TGS was introduced, the last lot of power cars were built as Driving Motors. Many DMBs were converted to DMs when the Guard's equipment was removed. Lot No.s were used for LHCS/DEMU/DMU/EMU/NPCCS vehicles (brucie bonus for the first to recall what NPCCS are!).

Look at photos from the introduction of the fleets in the 1970s - the WR numbered their sets with the 2530xx set number and the ER used the 2540xx set number.

What changed was that by the mid-1980s unit formations had been changed a lot (introduction of TGS; swapping around the different types of catering cars) that operating them as fixed units became less efficient than having the coaching sets remain fixed and the power cars used separately. It was I think 1988 that they became officially classed as Class 43 locomotives - Platform 5 books before that time listed the power cars with the trailers, talked of Class 253 and 254 and still listed the power cars as DMBs/DMs, with their diagram numbers (Dia. GB502 for DMB; Dia. GB503 for DM) and Lot No.s: -

• 43002-43055 Lot No. 30876 Derby 1976-77
• 43056-43123 Lot No. 30895 Derby 1977-79
• 43124-43152 Lot No. 30941 Derby 1979-81
• 43153-43190 Lot No. 30946 Derby 1980-81
• 43191-43198 Lot No. 30968 Derby 1982

Furthermore, the prototype Mark 3 vehicles were renumbered from the convential LHCS series to that used by the HST (which included the power cars being renumbered too). Why do this if HST trailers were convential LHCS? For reference the changes were: -

• Buffet 10000 to 40000
• Kitchen 10100 to 40500
• First 11000/11002/11003 to 41000-41002
• Second 12000/12002/12003 to 42000-42002
• Power cars 41001/41002 to 43000/43001

If the trailer cars were just normal LHCS they would have been numbered as such, with the Mark 3A/3B stock. Mark 3 was used for the HST trailers because this was the type the prototype vehicles were.

The fact is that the HST fleet was operating as a DEMU for about a decade, and even by the mid-1980s the fully fixed formation (DMB/DM + trailers) was dead. Remember though, many first generation DMU vehicles also operated as "loose" vehicles, but nobody would call a Class 101 TSL a Mark 1 LHCS because of that! Since the late 1980s the power cars have been locomotives (Class 43) and the trailer cars have been simply Mark 3.

So the Class 253/254 wasn't classified as such in error, it simply fell out of use. Furthermore, the HST was originally the HSDT (High Speed Diesel Train). It was a stop gap train - BR's true HST was the ill-fated APT! HST was marketed by BR as the InterCity 125, and being of an age that remembers BR I refer to it as a 125 rather than a HST. When the Class 91 and Mark 4s were introduced they were marketed as the InterCity 225 (225 km/h = 140 mph). (There was also the shortlived attempt to brand 110 mph Class 87 + Mark 3A sets on Euston - Scotland services as InterCity 175, this being 110 mph in km/h!)

HST became more common after privatisation, because the TOCs didn't wnat to talk of an IC125, so the HST name became more common again.

So Class 253, Class 254, Class 43 + Mark 3 Trailers, HSDT, HST, InterCity 125 - all one and the same train, that will be with us into the 2020s.

 

[ChrisCooper]

Not quite. 442 Mk.3s don't use MA sets, they use a converter and they were found not to work too well when fed from a loco ETS supply so the ETS feed was disabled years ago.

And although they can be hauled by a loco, you probably wouldn't want to use disc braked triple-valved passenger stock these days

Actually thinking about it the hauled Mk3s use a static converter too AFAIK. I know the Mk4s do. Mk2s have an MA to turn the single phase ETS to 3 phase for the aircon though.

I presume the use of 415v 3 phase for AC was so off the shelf industrial equipment could be used?

 

[dubscottie]

Actually thinking about it the hauled Mk3s use a static converter too AFAIK. I know the Mk4s do. Mk2s have an MA to turn the single phase ETS to 3 phase for the aircon though.

I presume the use of 415v 3 phase for AC was so off the shelf industrial equipment could be used?

The Mk2's used M/A sets to get round the problem of providing a constant AC voltage to the A/C units regardless of what loco pulled them without blowing fuses.
Even still some Mk2 D's could not be heated by 47401-20 and Deltics as their ETH output fluctuated to much as the DC ETH generator was mounted directly onto the engine output shaft.
The Mk2 Pullmans did not have M/A sets and, until they were rebuilt, could only be heated by AC locos as they were the only ones that could provide a constant AC ETH voltage.

 

[ChrisCooper]

Another thing with the HSTs was the maintenance facilities. They were built to service full sets, unlike previous depots where locos and coaches were maintained and serviced seperatly. It was later on that it was decided that is was easier to seperate the servicing and maintenance of the powercars and the coaches.

When it comes to the likes of Eurostars and TGVs, these are also serviced as full sets (or in the case of Eurostars, half sets, although even there they will usually be kept together). Powercars can be and are swapped at times, but will always eventually return to their original formations. DMU and EMU coaches are also swapped from time to time due to a major failure or accident, again always returning to their original formations.

 

[mallard]

DMU and EMU coaches are also swapped from time to time due to a major failure or accident, again always returning to their original formations.

Not always, sometimes MU coaches are permanently moved to other sets. The ex-508 coaches in the 455/7s and the movement of 158 center carriages come to mind as examples.

 

[IanXC]

And then to further mix things up there's the Mk.3 coaches used to make up a Cl.442

Power operated doors, 3-phase electrics, bar-coupled between coaches (drophead buckeye between units), SR EP/triple-valve brake system, SR MU system, etc

Sorry to go slightly off topic.. but are these doors a good example of what we're likely to see on the Chiltern Mk3s?

 

[MrC]

Actually thinking about it the hauled Mk3s use a static converter too AFAIK.

Another 442 difference is that there was one converter for the whole unit, ie 5 coaches. I've no idea if the inter-coach electrical connections are similar to those on the HST sets or unique to the 442.

 

[dubscottie]

Sorry to go slightly off topic.. but are these doors a good example of what we're likely to see on the Chiltern Mk3s?

Yes.. CIE Mk3's!!

Anyone guess what the Mk4 MU is yet?

Maybe one for the quiz section!

 

[LE Greys]

Yes.. CIE Mk3's!!

Anyone guess what the Mk4 MU is yet?

Maybe one for the quiz section!

I take it we aren't talking 323s, the body bears a distinct resemblance to the 158.
All Turbos are out, and that rules out Networkers as well, and by extension Turbostars (all built of extruded aluminium and a brand-new design).
All Sprinters, 317, 318, 319, 320, 321, 322, 455 and 456 are Mk.III-based.
Apart from anything post-privatisation, I'm out of ideas.

 

[dubscottie]

I take it we aren't talking 323s, the body bears a distinct resemblance to the 158.
All Turbos are out, and that rules out Networkers as well, and by extension Turbostars (all built of extruded aluminium and a brand-new design).
All Sprinters, 317, 318, 319, 320, 321, 322, 455 and 456 are Mk.III-based.
Apart from anything post-privatisation, I'm out of ideas.

Lets say the chicken came before the egg (the egg being the MK4).. they have steel bodies and all survive. Take out the interior fittings and the body structure is exactly the same..
--- old post above --- --- new post below ---
I must add even after a few major accidents they have all been repaired when some of their Mk3 counterparts were scrapped..

 

[ChrisCooper]

156? They are steel though aren't they, rarther than the Aluminium of the Mk4s?

 

[WillPS]

156s are Mk3.

 

[lewisf]

156s are Mk3.

I think you'll find the're not

I'm pretty sure I've seen somewhere (probably wiki) that the 156's are related on Mk4's.

 

[Royston Vasey]

Lets say the chicken came before the egg (the egg being the MK4).. they have steel bodies and all survive. Take out the interior fittings and the body structure is exactly the same.

As per the other thread, the body structure is plainly not the same! For a start the tilt profile is vastly different to the mild curvature of the 156 body.

This is like people saying Mk 2Fs and Mk 3s are very similar... only to the untrained eye! The Mk 3 has an all-steel monocoque construction like the 2F, so there is a similarity and a progression as it were, but you saying the 156 is the same as a Mk 4 is like saying the Mk 2F is a Mk 3, which it isn't!

 

[sprinterguy]

156s are Mk3.

That's what I've always believed. Other than both 156s and mark 4s being products of Metro Cammell and comprising steel bodyshells I really can’t see many similarities.(IIRC the APT-P trains on which the mark 4 carriages were based were of aluminium construction, but the mark 4s themselves are steel, which is why they are so heavy compared to previous carriage designs)
--- old post above --- --- new post below ---

I'm pretty sure I've seen somewhere (probably wiki) that the 156's are related on Mk4's.

It is indeed on Wikipedia, and is at least referenced to a paper with an official sounding name. I'm not inclined to believe it just yet though.

 

[mallard]

Only thing I could think of would be the 151s, but they've all be scrapped (and they were 20m stock, so different). I believe that the Nightstar stock is similar to the Mk4 design, but they're not MUs and came after the Mk4...

Maybe it's a non-UK design?

 

[Royston Vasey]

Only thing I could think of would be the 151s, but they've all be scrapped (and they were 20m stock, so different). I believe that the Nightstar stock is similar to the Mk4 design, but they're not MUs and came after the Mk4...

Maybe it's a non-UK design?

I think its more a case of the OP (no offence intended) becoming a bit carried away based on a Wikipedia reference. We haven't seen the actual content on which the assumption has been interpreted!

 

[WillPS]

I think you'll find the're not

I'm pretty sure I've seen somewhere (probably wiki) that the 156's are related on Mk4's.

I've read that one of the reasons MetroCammell lost out on the initial Sprinter order was that unions threatened to block them since they were from a non-union source (the union for railwaymen and BREL workers was the same back then). To counter this, MetroCammell sourced Mk3 parts from BREL for use in their 156 design.

I have no reference, but I believe this to be true - and when you look at them the cross section is very Mk3.

 

[boing_uk]

The Class 150 and 156 bodyshells really arent that much different.

What makes the body profile so pronounced on the 156 is the lack of tapered vehicle body ends as found on the 150.

 

[dubscottie]

The Mk4 is based the 156. when I said the structure is the same I was not talking about the body shape. (in the same way a 75ft Mk3 is a different shape to a 321 or 150)

They used the same jigs on both the 156 and Mk4 so both could be built by outside producers.

Met-Cam looked at a Mk3 type structure but the time and cost of providing the pressing tools to 3 or 4 different suppliers would have been astronomical.

I got this from an old Modern Railways mag from 1988/9 (need to look it out). I could stick up bits of the article (hope I don't get done for copyright!!)
--- old post above --- --- new post below ---
Found it.. Its the October 1989 issue.

In a Mk 3 the top-hat section verticals (the downward bits) are pressed over the long horizontals by "pressing" them.

When Met-Cam only had 6 months to develop the 156 they had to use a simpler structure as it would have taken 2 years to develop the tools to "press" sections of the structure.

They had the same time scale for the Mk4 so updated the 156 body to UIC end loadings.

On a 156 and a Mk4 only the vertical sections are continuous and short horizontal sections are used in between. This gives (unlike a Mk3) a flat surface to mount the interior. The are also thicker which gives better sound insulation. Also as the structure is simple, both BREL Crewe and BREDA of Italy (the last 32 TSO's) built Mk4 shells without expensive tools.

An interesting bit in the article was about "bodyside ripple" It was only allowed to be +/- 35mm per of metre of bodyside. It does not look like they met this going by the amount of dirt that builds up between the vertical pillars on the new Eastcoast livery!

Another point is that 2 Class 150 cars were written off when only a few years old (St Helens and Seamer). However 156490, which had much more damage (nothing was left forward of the toilet) was repaired.. Maybe due to the simplicity of its bodyshell design.

 

[starrymarkb]

158/9

Try Class 156

The Mark 4s are a Metro-Cammell product.

Classes 158/159 are BREL products

 

[ChrisCooper]

The problem is people often confuse looking alike as to being constructed similarly, and conversly looking different as to being totally different construction. For many with BR stock if it's got slam doors it's a Mk1, if it's got sliding doors it's a Mk3 and if it's got plug doors it's a Mk4, with a few exceptions. In reality things can look quite different yet be near identical under the skin, or look identical yet be of very different construction.
The 1st generation DMUs were great examples of the latter, they all looked similar (with ovious exceptions) but were built by different manufacturers using different techniques. Few had much in common with Mk1s structurally.

 

[sprinterguy]

Ah well, you learn something new every day. The mark 4s definitely have a heck of a lot of "bodyside ripple" going on I've noticed. I've occasionally wondered why they seem to be afflicted by this much more than other UK rolling stock.

 

[starrymarkb]

The problem is people often confuse looking alike as to being constructed similarly, and conversly looking different as to being totally different construction. For many with BR stock if it's got slam doors it's a Mk1, if it's got sliding doors it's a Mk3 and if it's got plug doors it's a Mk4, with a few exceptions. In reality things can look quite different yet be near identical under the skin, or look identical yet be of very different construction.
The 1st generation DMUs were great examples of the latter, they all looked similar (with ovious exceptions) but were built by different manufacturers using different techniques. Few had much in common with Mk1s structurally.

Very True - eg Class 325 is another Mk3 unit (basically being a freight 319) but look how many think they are Networkers because of the cabs

Big difference - Networkers have Asynchronous traction, 325s are DC Thryistor traction.

Should probably go and see what Wikipedia says (having corrected this several times!)