Differences between MK3 and MK3a trailers

[richscylla]

Hi all! 

What is the difference between MK3 and MK3a trailers. I (think I) know MK3s are HST stock and MK3a are loco hauled but what are the other differences? I know the 3a's have buffers and MK3 don't, but what are the other differences? I'm asking as I'm thinking about trying to convert some Oxford MK3a's to HST stock, but I'm not sure if it's actually a much bigger job than I'm thinking it might be. 

 

Thanks, 

 

Rich

[Flood]

Mk3a Firsts and Seconds have Roevac vents above the end vestibules, Mk3 stock have the square plenum chambers.

 

Strictly speaking there are also variations in the modules between the bogies as well.

[DY444]

Would I be right in thinking the Mk3a has built in tail lamps?

[Bomag]

21 minutes ago, DY444 said:

Would I be right in thinking the Mk3a has built in tail lamps?

 

Only the sleepers and Mk3bs had the build in tail lamps.

 

The following HST trailers were originally production Mk3a

 

41193-41195 (cross country)

41201-41206 (GC and now MML)

42366-42378 (cross country)

42382-42383 (GW)

45001-45005 (cross country)

 

From comments about the conversions, the still retain the original ETH equipment but with an additional module to convert the three phase AC supply.

 

[Covkid]

On 09/03/2019 at 16:47, Bomag said:

 

Only the sleepers and Mk3bs had the build in tail lamps.

 

The following HST trailers were originally production Mk3a

 

41193-41195 (cross country)

41201-41206 (GC and now MML)

42366-42378 (cross country)

42382-42383 (GW)

45001-45005 (cross country)

 

From comments about the conversions, the still retain the original ETH equipment but with an additional module to convert the three phase AC supply.

 

 

Not totally sure but I think one of the Cross Country catering cars was actually a HST trailer. I think they are one of one kind, two of another and two of another, but will find out from an expert at work.

 

To answer the OP, the production Mk3s were designed as HST trailers with Alliance couplers, 415V three phase electrics and MU cables, although the prototype set was actually designed to be loco hauled with standard wiring, side buffers and drophead buckeyes. 

The Mk3a and subsequently Mk3b were built as loco hauled vehicles with standard ETS, drophead buckeyes and retractable side buffers.

One bodyshell covered first and second class designs then later the DVTs and the three BFOs were added as Mk3s    

[Bomag]

1 hour ago, Covkid said:

 

Not totally sure but I think one of the Cross Country catering cars was actually a HST trailer. I think they are one of one kind, two of another and two of another, but will find out from an expert at work.

 

To answer the OP, the production Mk3s were designed as HST trailers with Alliance couplers, 415V three phase electrics and MU cables, although the prototype set was actually designed to be loco hauled with standard wiring, side buffers and drophead buckeyes. 

The Mk3a and subsequently Mk3b were built as loco hauled vehicles with standard ETS, drophead buckeyes and retractable side buffers.

One bodyshell covered first and second class designs then later the DVTs and the three BFOs were added as Mk3s    

 

The TCTs were originally 12004, 12101, 12076, 12077 and 12080.

 

Mk3a had three body shells, TSO/FO; RUB and sleeper.  The roof end vents of the latter two were as Mk3 production stock.

[roythebus]

I'm thinking of doing a similar conversion of some Jouef Mk3's I picked up in good condition from a fair a few years ago. Is there much difference on those models to the HST trailers?

[Flood]

See post 2. The Jouef open firsts and seconds have the correct roof vents and underframe modules for Mk3a stock like the Oxford ones. The Jouef buffets have roevac vents when they should have plenum chambers for the Mk3a RUB stock, like the HST Mk3 TRUB coaches which were built around the same time in 1979.

 

Lima HST coach above, Jouef Mk3a below. Sorry about the photo quality:

Edited March 11, 2019 by Flood

[westie7]

I'm using a stash of mega cheap Jouef coaches as the base for loco hauled and buffets. With a bit of modelling it turns out quite good

 

So if anyone has spare Lima Mk3 roofs, pm me as I'll need a few

 

Cheers

Mark

 

[Steven B]

Are the couplings on HST Mk3s compatible with those fitted to standard loco hauled Mk1, Mk2s etc? I've seen Mk1 and Mk2s used as barrier vehicles but don't know if the coupling at one end has been changed or if any drop buck-eye fitted coach could be used.

 

Steven B

[seraphim]

Drophead buckeyes as fitted to Mk1/2/3 coaches can couple to the fixed-head Alliance coupler on the HST trailer. However, the couplers are slightly different, and this combination is prohibited in public service. An HST barrier is simply a coach with a drophead buckeye at each end; the barrier therefore runs with the drophead lowered at one end- exposing a standard drawbar which can be used with a normal loco screw coupling, and the drophead raised at the other, which can couple to the Alliance. All of this came to light in a memoreable debacle at Oxley depot in the 1990s with a trailer knocked out of a passing HST set and a series of efforts to return it to Neville Hill.

[Natalie]

As far as I know the couplers on HST Mk3s are compatible with those on Mk1,2 and 3a/b vehicles. There are a number of photos of mixed HST Mk3 and Mk3a formations in the early years of the class 253 HST involved in non-revenue work. The set used for the 140 mph tested also utilised M12140 coupled to HST Mk3s in the formation. Pictures are on traintesting.com. The main difference as I understand between the couplers on the HST and the loco-hauled Mk3s are that those on the HST are fixed in the raised condition whilst those on loco- hauled coaches- (not Mk4) are droppable so as to expose the drawhook. This is why barriers are required as a HST Mk3 cannot be coupled directly to a loco via a screw coupling- class 73s fitted with buckeyes have been used in the past though as they have a buckeye and a rubbing plate.

[jim.snowdon]

Railway Group Standard GM/RT2509 makes for interesting reading, not least Appendix C, which includes a table showing the coupler compatibilities.

 

Jim

[roythebus]

So, not being too fussed about the roof vents, presumably if I cut off the Jouef buffers they'd be ok for HST trailers? What do others do to make the Jouef coaches free'er running? I've used some Romford disc brakes 12mm wheels on pinpoint axles (I've got hundreds in stock) but the plastic axle boxes don't lend themselves to free running despite my best efforts. Also, what's the easiest way to close-couple them?

[uax6]

Can you get top hat bearings in the bogie axleboxes? If you can that should transform them.

 

Andy G

[roythebus1]

Revisiting this old thread, I found a couple of the original Hornby HST power cars in a cupboard. I stripped the motor bogie as it didn't work, the brushes were worn out.

 

So I oiled it, put it back together with brushes from another motor bogie, and it squealed. 3 times I stopped and oiled it...then checked the bottle of oil. It was actually Carr's flux for low melt soldier!! Grrr, another strip down, clean flux off, use oil and re-assemble. this time it works quite nicely.

 

So, back to the Jouef coaches, it's possible to fit top hat bearings, but the Jouef plastic is very unforgiving. Maybe a bit of drilling out then gentle heat to melt the top hats in. then some Kean KK units with Hornby or Roco KKs, maybe a quick repaint and off we go!

 

Presumably the correct ECML version would be M-2-2-RUB-2-2-1-Restaurant-1-M ? I can't remember, it's been a long time since I've seen one!

[Pete the Elaner]

8 minutes ago, roythebus1 said:

 

Presumably the correct ECML version would be M-2-2-RUB-2-2-1-Restaurant-1-M ? I can't remember, it's been a long time since I've seen one!

 

I think only a couple of sets had 2 buffets & that made them 9+2.

Only early HSTs had a TS at the country end. The guards found their power car compartments noisy so the TGS were introduced.

This made the standard 8+2 formation DM-TGS-TS-TS-TS-TS-(RUB/TRUB/RFB)-TF-TF-DM.

[roythebus1]

One of the other threads I've just looked up showed showed what I thought the formation would be during the Penmanshiel diversions. Interesting times. I'm not too fussed, it'll have to be what I've got to hand! I know there's a Jouf restaurant of some sort and the long Hornby restaurant of some sort and some 1st and 2nd class cars, not sure how many yet!

 

I've also dug out my Kitmaster Blue Pullman, so that'll make a nice addition.

 

[EddieK]

As I happen to have the 1982 RCTS coaching stock book to hand, here is a quick overview of HST sets at that time: -

 

WR sets 253001 - 253040: TF-TF-TRUB-TS-TS-TS-TGS but sets 010-017 had TRSB vice TRUB

WR sets 253041 - 253058: (Cross Country): TF-TRSB-TS-TS-TS-TS-TGS

 

ER/ScR 254001 - 254011: TF-TF-TRUK-TRSB-TS-TS-TS-TGS

ER/ScR 254012 - 254020: TF-TF-TRUB-TS--TS-TS-TGS   note only 7 trailer cars

ER/ScR 254021 - 254037: TF-TF-TRUB-TS-TS-TS-TS-TGS

 

Around that time, the HST catering provision was very much subject to change.

 

 

[Bomag]

In 1980 the original ECML sets with two catering cars went from TS/TS/TRSB/TS/TS/TRUK/TF/TF to TS*4/TRSB/TRUK/TF*2 (with the seating portions of both catering cars generally next to each other).  I believe it meant that that you could operate them with less staff. Don't forget if you are running a ECML HST in 1979/80 that the power cars didn't have the later exhaust deflector and that the first TGS delivered to the ER (44041) was in October 1980.

 

The ECML TRUB sets were introduced from August 1978 (40310) but the majority of these were allocated to NL and while they were common at Newcastle (running many of the 00:30 services off the cross) they would be less so on cross border services in this period. The ER was perennially short of TS until the last batch of TS were delivered in 84/85 so you could run a set diverted due to Penmansheil with a couple of TS missing.

 

 

 

 

 

 

[roythebus1]

Interesting, thanks.