Multiple Units Vs Coaches & Locomotive

Discussion in 'Off Topic' started by Mattty May, Oct 16, 2020.

  1. Mattty May

    Mattty May Guest

    What is the advantage of having Multiple Units versus Coaches with Locomotives?

    The way I see it, the coach and loco configuration is much more flexible and would allow train operators to add or remove coaches quickly and easily depending on capacity needs. Not only that but you can add locomotives if you need more oomph and can swap a locomotive out with ease if it develops a fault without losing capacity.
     
    Last edited by a moderator: Oct 16, 2020
  2. Luke8899

    Luke8899 Well-Known Member

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    Performance-wise EMUs accelerate much much faster than a loco-hauled set, as they have several powered bogies throughout the length of the train as opposed to a loco doing all the work at one end. Decent acceleration is much-desired even on long-intercity routes because being able to get to a top speed quicker means more time spent at higher speeds and therefore lower journey-times. (On this train of thought, ba-dum-tish, here's an interesting article not directly related to your question but it touches on how important acceleration is).

    I also seem to remember in the UK a decade or so of Network Rail lobbying against loco hauled passenger sets on the basis locos cause more track-wear than more evenly weight-distributed EMUs.
     
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  3. ARuscoe

    ARuscoe Well-Known Member

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    I think it comes down to two things, weight distribution and power distribution

    In a loco hauled service you might have a heavy loco at the front and a few carriages behind and this means that in certain weak spots the loco may be too heavy and need to slow down, whereas a MU set would not. Best example I can think of is on the Wherry lines outside Norwich where loco hauled services have to slow to 20 where an MU can sail over at 60. The weight and pressure that the loco puts into the ground is too high for the bridge, but a "lighter per meter of length" MU doesn't have that issue

    The other thing is that in MUs you generally have more than one engine and/or motor, so if one breaks down you may well be able to continue on the power of the other. Certainly I've been on class 158s where one unit developed a fault but the train could continue on the power of the other

    Your comment of versatility is a good one, but this is why MUs are able to hook up together. If you need to increase capacity of a given service chuck a compatible MU on the back, even if it's as a dead unit. So long as the couplers match up and the power systems are compatible you're pretty much OK
     
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  4. Northerner

    Northerner Well-Known Member

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    There's also platform lengths to consider, a HST has around 38 metres that is taken up by the power cars, which therefore means at a bay platform you have all that space effectively wasted. On a multiple unit, all of the engines are under the carriages, so you can have more passenger accommodation. I may be misremembering, but I think this is one of the reasons that the class 800s were chosen for GWR over a design similar to the HSTs which I think was once planned. Though there are always exceptions, such as the class 755 which has a power pack in the middle.
     
    Last edited: Oct 16, 2020
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  5. ixofxiii

    ixofxiii Well-Known Member

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    Don't forget as loco hauled consists may be easier to add cars, they take longer to relay. Plus, most commuter railroads operate push-pull. Thr loco or cab car has to be uncoupled to add cars. Unless you're NJT and just add cars regardless. Lol
     
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  6. Luke8899

    Luke8899 Well-Known Member

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    I thought this video might be of interest to some here. The 19th century solution to slow acceleration... Just don't stop the trains at all stations!

     
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  7. Luke8899

    Luke8899 Well-Known Member

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    Now we must oblige DTG to commit not just to steam, but to fully working slip coach operations in multiplayer mode. Bagsy being the guard in charge of bringing the slip coaches to a halt! xD
     
  8. SHINO BAZ

    SHINO BAZ Well-Known Member

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    Well there are some routes where you can uncouple the last coach an possibly even turn the brake wheel to stop it.um the west summer set line might worth trying it on.it does have a brake guard in the last car i think or maybe try it on NTP it uses a baggagecar at the end of it's trains that should have a brake wheel onboard.
     

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