Could Mark 3 sleeping cars be put in HST sets?

Discussion in 'Traction & Rolling Stock' started by PaxmanValenta, 11 Apr 2015.

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  1. PaxmanValenta

    PaxmanValenta Member

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    Mark 3 sleeper carriages have always been loco hauled, but since the bogies and chassis are the same as normal HST trailer carriages, could sleepers be put into HST sets for longer distance sleeper services?

    I think it would be good because HST cross country services like Penzance to Aberdeen could have a few sleeper carriages in their sets if they wanted to run night services.
     
  2. ainsworth74

    ainsworth74 Moderator Staff Member Moderator

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    You'd need to re-wire the sleeper vehicles as the loco hauled Mk3s use a different power system to the HST Mk3s. Not impossible but it does mean they can't just 'plug and play'.

    The larger issue is that no one is going to want to run night services between Penzance and Aberdeen or anywhere really beyond the areas that already have sleepers...
     
  3. 61653 HTAFC

    61653 HTAFC Established Member

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    The electrical supply (for heating, lighting, air-conditioning, etc.) is different on HST sets and loco-hauled Mk.3s. Individual coaches have been rewired for HSTs (in particular for Grand Central) but it isn't cheap. I've often wondered if, in the event that using 43s on the sleeper permanently was desired, it might be a better idea to change the supply on a small sub-fleet of power cars rather than rewiring all the coaches. Such a thing wouldn't possibly be viable until after the 800s arrive and the power cars aren't in quite so much demand though.
     
  4. Failed Unit

    Failed Unit Established Member

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    GNER were going to do it. But as it happened the Virgin sets came of lease so a trailer was taken from them. The artist impressions had wierd windows on them.
     
  5. danielnez1

    danielnez1 Member

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  6. ainsworth74

    ainsworth74 Moderator Staff Member Moderator

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    Though wasn't it so structurally unsound that it could only be moved by road?
     
  7. David Goddard

    David Goddard Established Member

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    Never say never! We saw from the GC examples that conversion can happen and if the right people have the will, the time and the money then it could happen. As 61653 says, now we are this close to the 800s, it is more likely that a fleet of 43s would get converted to match the stock rather than the other way round.
     
  8. danielnez1

    danielnez1 Member

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    I don't know about that, though I am sure they wouldn’t have shown it in public if there were doubts about the coach’s structural integrity.
     
  9. Bletchleyite

    Bletchleyite Veteran Member

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    Yes, I recall that being the case; the structure is I believe different from a regular Mk3. I recall there also being a proposal to make one with the small windows with very generous seat spacing to compensate.
     
  10. Peter Mugridge

    Peter Mugridge Established Member

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    I don't think they showed it in public; only at a Railtex exhibition.
     
  11. DownSouth

    DownSouth Established Member

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    Why were the HST power cars specified with a non-standard electrical supply system? Was it an artefact of a compromise somewhere in the design, or a deliberate attempt to ensure they couldn't be used with other conventional coaching stock?

    The XPT works well as a sleeper, thanks to the excellent Budd-designed coaches which won the competitive tender ahead of the BR Mark 3. I don't know any details of whether Commonwealth Engineering built the power cars and coaches with standard HEP or the unique HST voltage, but I do know that the BR-style knuckle couplers were used instead of the proper full-size ones (ruling out compatibility with other coaches) to make sure a XPT power car could never be seen hauling freight.
     
  12. edwin_m

    edwin_m Veteran Member

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    Interesting question. I believe the prototype HST had a standard ETH supply so could in principle run with any air-braked and electric heated stock. Was using a three-phase supply for the production versions no more than a bid to save a bit of weight and cost by avoiding fitment of a motor-alternator on each coach?
     
  13. 43167

    43167 Established Member

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    Correct, the prototype does indeed have standard ETH.
     
  14. route:oxford

    route:oxford Established Member

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    Perhaps a three-phase supply is easier to balance/phase(?) across two supplies 9 coaches apart?
     
  15. 455driver

    455driver Veteran Member

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    What is your knowledge of these 3 phase supplies then?

    Only one power car supplies the supply to the coaches!
     
    Last edited: 12 Apr 2015
  16. PaxmanValenta

    PaxmanValenta Member

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    I guess the only other option could be to convert some HST TSO or FO mark 3 trailers to sleeper coaches by building compartments in them, or making them composite FO/sleeper.
     
  17. Bletchleyite

    Bletchleyite Veteran Member

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    If the CAF stock for the Scottish sleeper is successful, it'd make more sense for fGW to buy some of those with a driving trailer and a small Class 68 fleet.
     
  18. cjmillsnun

    cjmillsnun Established Member

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    Agreed.
     
  19. DarloRich

    DarloRich Veteran Member

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    In theory: Yes. In practice: No. What would be the point or the need?
     
  20. Murph

    Murph Member

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    As far as I can tell, both LHCS and HST mark 3s are standard 415VAC 3 phase (which means you also have 3x 240VAC single phase where required), internal to the vehicles. The difference is that the LHCS have a motor-alternator set per coach to convert from traditional 750-1000VDC supply to standard 415VAC. Modern refurbs and retrofits can, of course, use a solid state static converter, thanks to several decades of advances in high power electronics, instead of a big spinning shaft with DC in one end and AC out the other. I wouldn't want to swear to LHCS mark 3s having only the motor-alternator hooked direct to the DC, but it certainly appears to be done like that to allow common/standard "off the shelf" industrial electrical gubbins.

    HST trailers basically save the weight of the converter by running an AC bus down the train, and they obviously also have the necessary HST multi-working cables to link the power cars.

    (The above is based on a lot of reading, including the specs publicly provided by some ROSCOs. Anyone with direct hands on, please feel free to correct me as needed.)

    Going by the blog, that was a compromise made when rebuilding it. There's a blog article from the team which talks briefly about changing from 3 phase to DC for the auxiliary generator. I believe it was originally the same as the 43s for hotel power.


    As for the question asked by the thread, sure, they should be able to be converted just like any other mark 3. In principle, it should be "simple and easy" (but that doesn't mean quick or cheap), unless they have an unusual peculiarity compared to normal mark 3s. Whip out the motor-alternator, extend the 415VAC wiring to come out both ends as a suitably heavy duty bus, then add the HST multi jumpers and bus. Oh yeah, and don't forget the overload protection devices sprinkled on as required.
     
    Last edited: 12 Apr 2015
  21. cjmillsnun

    cjmillsnun Established Member

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    Do we know the frequency of the AC output by the MAs or by the HST power cars? It could be as simple as them being totally different.

    And no that isn't beyond the realm of possibilities. Civil aircraft have 400 Hz AC electrics for example.
     
    Last edited: 13 Apr 2015
  22. dubscottie

    dubscottie Member

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    The Prototype had standard ETH as the prototype Mk3's were ordered in 1970 and built as Loco-hauled stock (and were numbered as such).

    IIRC one FO and one TSO were ordered by the LMR for trials and the ER then ordered the same (hence different lot numbers).

    All the prototype coaches were then used for the HST, the buffet cars being ordered much later..
     
  23. cjmillsnun

    cjmillsnun Established Member

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    The prototype had standard ETH as built, however in 1974 it was returned to the works, and a three phase system fitted, as this post on Project Miller explains...

    http://www.projectmiller.org.uk/?p=781
    NB this part is long since sold.

    I'm guessing when the PCs went into the departmental pool, they were reverted back to standard ETH to enable them to power the departmental stock.
     
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