Talk:Multiple unit

message: "Multiple unit" can mean either (1) a system for controlling multiple railway vehicles
from a single driving station, or (2) an independently powered rail car capable of being joined into
a train controlled in this way, or (3) the resulting train.  MU control can be used for
locomotives, single cars (sense 2), or trams/streetcars.
Currently we have these articles (at least), with a severe shortage of links
between them:
* diesel multiple unit - disambiguation of sense 1 (applied only to locomotives) and 2
* diesel multiple units - uses sense 2
* multiple unit - uses sense 3, overlaps the above article but is better written
* multiple-unit train control - defines sense 1 (ignoring locomotives)
* railcar - this term can mean sense 2 or a strictly independent powered car; the article touches on this and links to "multiple unit"
In addition there is conflicting information.
"Multiple unit" says that the term diesel multiple unit (DMU) means one with a
mechanical gearbox, which I have also seen called a DMMU (diesel-mechanical),
while one with electric transmission is a DEMU (diesel-electric). On the other hand,
"Diesel multiple units" says that the term DMU implies electric transmission.
Neither one mentions the third option, hydraulic transmission (DHMU), as
I believe the Budd RDC cars had.
Not only does the terminology need to be sorted out (perhaps some of the
differences reflect British vs. North American usage, or other limited points
of view), but I think the structure we need is:
* multiple unit - disambiguation
* multiple-unit control (renamed and expanded to mention locomotives)
* multiple-unit train (acknowledging senses 2 and 3, and combining the "multiple unit" and "diesel multiple unit")
As railcars are not necessarily MU vehicles, I would leave that article substantively alone except for tidying up;
the "multiple-unit train" article should link to it, though.
(anonymous, 2005-01-22, 05:06 UTC)
:I concur and wish to copy this to the Trains Project Page so that others will be informed.  I do however wish to add that there should be a seperate Multiple Unit Vehicle page to seperate your sense 2 from multiple-unit train.  And likewise, this all makes sense for North American Railroads, but I would need input from other continents to see if this works with their systems at all.  Skabat169 17:33, 16 June 2006 (UTC)
replies: text: I would avoid the term "railcar"; I've always understood this to refer to a self-propelled carriage, although in the US it just refers to any train car. The Wikipedia article "railcar" also notes the confusion around this term. To me, a railcar means "self-propelled", while multiple unit trains have carriages that are useless when isolated, for example a train with driving trailers and separate motor cars (such as the British Rail Class 319) where no car in isolation is capable of anything. Ghiraddje 23:22, 26 December 2009 (UTC)
thread_title:  Organization 

message: Since the rolling stock for the river line consists of Diesel-Electric self-propelled units, should these be referred to as "DEMU's" in the North America sub-section?TimeriderTech 05:20, 14 Apr 2005 (UTC)
thread_title:  River Line in New Jersey 

message: Any reason for inclusion here? No page for Hybrid Train, re-directs to Hybrid Locomotive, no apparent relevance to Multiple unit. Probably should be removed.  Keo 01:13, 30 October 2006 (UTC)
thread_title:  Hybrid Train link? 

message: I have modified the page to include disadvantages of MUs as well as their advantages. The same has been done to the locomotive page for fairness Dellarb 10:21, 6 November 2006 (UTC)
thread_title:  Disadvantages 

message: I am moving the following passage here from the article, because I dispute it.
A multiple unit train consist has the same power and traction components as a locomotive, but instead of the components concentrating on one carbody, they are spread out on each car that make up the consist. Since the power and traction components are spread out on each car, these cars can only propel themselves when they are within one complete consist, thus make them semi-permanently connected. For example, a DMU might have one car carry the prime mover and traction motors, and another carry another engine for head end power generation; an EMU might have one car carry the pantograph and transformer, and another car carry the traction motors.
If the carriages are semi-permanently connected then what you have is not a consist of multiple units, but rather a single trainset.  The article lists one of the advantages of multiple units as the ability to quickly  make up or break apart a consist, which would be impossible if the carriages were semi-permanently attached.DHimmelspach 04:33, 11 March 2007 (UTC)
replies: text: Well, these trainsets can be multiple united together and break apart, but instead of make up or break apart by carriages, they must be made up or broke apart by trainsets. Maybe "a consist" is the wrong word to use here, but that is what I usually heard. What do you think "a consist" might mean? --Will74205 05:33, 11 March 2007 (UTC)

text: I just replace "consist" with "set" and place the statement back into the article, which is the intended meaning. --Will74205 05:46, 11 March 2007 (UTC)

text: Well I add it because most EMU and DMU are trainsets by observation, perhaps it should be reworded. Should we restrict this article to describe the capability to be multiple united together, or multiple unit trains. I am not entirely happy with the current introduction either. I guess we can expand the definition of Multiple Unit to include all train cars and trainsets that can propel themselves, combined with like units, and operate from one single control cab. In this definition, Multiple Unit also covers the the common US usage on locomotives. What I meant to describe was a trainset cannot move by themselves if they are not in one complete set, such that a motor car cannot move without a power car, and vice versa. This is what I meant by "semi-permanently connected". --Will74205 23:04, 11 March 2007 (UTC)
replies: text: My opinion - trainsets belongs in a seperate article.  These are typically entire sets meant to run as a unit with little switching out of cars while MU's are generally self-contained in single units or married pairs.  But this may just need further discussion and rewording.  Skabat169 05:00, 9 June 2007 (UTC)
thread_title:  Disputed Description 

message: Right now, the advantages/disadvantages section appears to be the biggest weakness. Multiple units, as defined by Wikipedia articles on the individual classes (all the articles that define train classes as multiple units), are of at least three types. The British Rail Class 319 EMU is a four-car unit that can be run in multiple (e.g. an eight-car train) but has a single motorised car in the middle, two driving cars and a trailing car. A British Rail Class 222 DEMU has all cars motorised, driving cars included. All TGV trains however, while commonly used in multiple, do still use locomotives at each end of the train. The advantages/disadvantages section has many good points but it contradicts the reality of multiple units. They don't have to have driving carriages instead of locomotives nor do they have to have every carriage motorised. All they require is that you can take two trains, join them end to end, and control both as one from a single cab. That is, unless you redefine multiple unit right across Wikipedia. Ghiraddje 14:33, 7 June 2007 (UTC)
thread_title:  Advantages/Disadvantages section 

message: Whoever re-wrote this article needs to do some revision about Wikipedia, and the need to verify all entries.  This article has ZERO citations/references.  All the time that has been spent on revising the article has to some extent been wasted, as the person(s) forgot to add any reference/citations. I shall review this page in one months time ... if it has not been improved then I shall recommend that it be deleted for not having any citations. I have given "fair warning" ... so act now.Sheepcot 20:52, 28 March 2007 (UTC)
replies: text: Instead of blaming others for not including references, perhaps you should try to find some yourself. The problem with Multiple Unit is that its usage varies slightly in the world. So the description in the article is meant to be as inclusive as possible while stating the differences between a multiple unit and a locomotive hauled train. --Will74205 22:02, 28 March 2007 (UTC)
replies: text:  Listen to me. I have pointed out a problem with this article.  I am not claiming to be a "lead editor" for this page, and claim glory when it gets its status improved.  All I have done is indicate a  flaw in the article that should have been rectified when the page was re-written.  It is not up to me to include the references, I see my role as more of a project manager. Sheepcot 22:09, 28 March 2007 (UTC)
replies: text: I see: a boss, not a worker. Why do assume, Sheepcot, that the plebs only contribute for "glory"? I agree wholeheartedly with Will74205. If you see a problem and can fix it, then do so (that, surely, is the true spirit of Wp). Otherwise I suggest you keep your negativist "fair warnings" to yourself. (Sorry to be rude, but some things just cannot be left unanswered.) -- Picapica 11:50, 23 June 2007 (UTC)
thread_title: Re-Write

message: I am attempting to seperate all the discussion of MU as in train control into the article Multiple-unit train control, leaving all discussion of MU the cars for this article, EMU, and DMU.  As such, I edited the article, fixing a few UK/USA problems as well.  Feel free to change the other edits, but the MU Train Control removals I would prefer that they're discussed here or at Talk:Multiple-unit_train_control first.  Thanks.
Skabat169 05:00, 9 June 2007 (UTC)
replies: text: The article still needs a major re-write.  In fact, I think its now worse than before.  Canterberry 12:15, 9 June 2007 (UTC)
thread_title: [[Multiple-unit train control]]

message: I totally agree about the lack of sources on this page, but this comment is just downright erroneous:
Axle load - Multiple units have lighter axle loads, allowing operation on lighter tracks, where locomotives are banned, such as the Whitby line in the UK. Another side effect of this is reduced track wear, as traction forces can be provided through many axles, rather than just the four or six of a locomotive
I've been down the Esk Valley Line in the recent years in a LHCS set, and I know of other operations using such. Perhaps certain heavy locomotives are barred due to their weight, but just to say "Locomotives are banned" is dubious to say the least. If I'm hopelessy and utterly wrong, do correct me, otherwise I will remove this claim in about a week.
--79.66.115.234 (talk) 00:04, 13 March 2008 (UTC)
replies: text: You can, indeed, remove the inaccurate sentence in the article if you know it's de facto wrong. -- Sameboat - 同舟 (talk) 00:50, 13 March 2008 (UTC)
replies: text: It is wrong - there's even a picture on the Esk Valley Line page of a locomotive on the line, in recent years. Admittedly it's hardly a modern one (it's a steam locomotive; it looks like the North Yorkshire Moors railway runs some to Whitby), but it's still a locomotive. I've removed that bit of text. Riedquat (talk) 01:56, 5 December 2008 (UTC)
thread_title:  Inaccuracy 

message: These look like complete faulse argumentations, problably because they are based on the caractheristics of the authors localized trains. 
Multiple units versus locomotive-hauled trains
Advantages
Multiple units have several advantages over locomotive-hauled trains:
Energy efficiency — MUs are more energy efficient than locomotive-hauled trains. They are more nimble, especially on grades, as much more of the train's weight (sometimes all of it) is carried on power-driven wheels, rather than suffer the dead weight of unpowered hauled coaches. In addition, they have a lower weight-per-seat value than locomotive-hauled trains since they do not have a bulky locomotive that does not itself carry passengers but contributes to the total weight of the train. This is particularly important for train services that have frequent stops, since the energy consumed for accelerating the train increases significantly with an increase in weight.''
- not always true , actually almost never true , a heavier locomotive would be considered as "travelling light" if it only would need to carry 3-6 cars behind
Higher acceleration rate — Because of the energy efficiency, higher power - to - weight ratio and higher adhesive weight to total weight ratio values, MUs generally have higher acceleration ability than locomotive type trains and are favored in urban trains and subways for frequent start - stop routines.
- it neglects the FACT that most of the MU's out there actually only have one or two motorized cars in a bigger consist so that argument is not that widespread as one would assume by reading this comment
No need to turn locomotive — Most MUs have cabs at both ends, resulting in quicker turnaround times, reduced crewing costs, and enhanced safety. The faster turnaround time and the reduced size (due to higher frequencies) as compared to large locomotive-hauled trains, has made the MU a major part of suburban commuter rail services in many countries. MUs are also used by most rapid transit systems. However it is necessary to note that this is no longer a problem for locomotive hauled trains due to increasingly widespread usage of push-pull trains.
- Everywhere theres top'n'tailing and push-pull consists "identical" to what this article passes as MU ... simply because localized traction (a.k.a. locomotive) and "fixed-permanent" consists are not mutually exclusive
Makeup can be changed mid journey — MUs may usually be quickly made up or separated into sets of varying lengths. Several multiple units may run as a single train, then be broken at a junction point into smaller trains for different destinations.
- again not a valid point ... it costs as much (time , manpower and such) to detach and attack two MU or two racks of coaches at a station ... 
Reliability — Due to having multiple engines, or motors, the failure of one engine does not prevent the train from continuing its journey. A locomotive drawn train typically only has one power unit whose failure will disable the train. Some locomotive hauled trains may contain more than one power unit and thus be able to continue at reduced speed after the failure of one.
- what has this paragraph to do with reliability ??? breaking up during a trip is not reliability ... is lack of it ... and again most MU only have one powered car. 
Safety — Multiple units normally have completely independent braking systems on all cars meaning the failure of the brakes on one car does not prevent the brakes from operating on the other cars.
- When did the MU started to have "independent brakes" on all cars ??? the brakings are centrally operated in most MU. 
Axle load — Multiple units have lighter axle loads, allowing operation on lighter tracks, where locomotives are banned. Another side effect of this is reduced track wear, as traction forces can be provided through many axles, rather than just the four or six of a locomotive
- again not true ... with distributed power the entire consist is heavier due to the increased weight spread evenly along the train ... with concentrated power the car that would be a locomotive in a loco hauled consist has the aditional weight of the passengers ... so twise untrue. 
- a loco hauled consist would be lighter due to the specialized nature of the cars (either powerhead or passenger/cargo)
Easy and quick driving — Multiple units generally have rigid couplers instead of the flexible ones on locomotive hauled trains. That means, brakes or throttle can be more quickly applied without excessive amount of jerk experienced in passenger coaches.
- and usually it's the other way around ... and what is "easy and quick driving" ... is this some joke or it's about "ride quality".
Allowance for accurate performance calculations for timetabling purposes - In a locomotive - hauled train, if number of cars is increased in order to meet the demand, acceleration and braking performance drops. This calls for the necessity that, the performance calculations are to be done taking the heaviest train composition into account. This may sometimes lead some trains in off- peak periods to be overpowered with respect to the required performance. But when two or more multiple units are coupled; train performance remains almost unchanged. However it is necessary to note that in loco hauled train compositions this problem can be solved by using more powerful locomotives when a train is longer.
- Timetables usually have Margins and Tolerances big enough to cope with these factors ...  
--- Not even worth mentioning the amateur~grade of the "disadvantages" section Sotavento (talk) 01:58, 24 June 2009 (UTC)
thread_title:  BIASED 

message: In Switzerland, there are quite a few things that are used like locomotives, but have seats or a luggage compartment. In contrast to what is normally considered to be a multiple unit, the pantograph, transformer, compressor, motors etc. are all in one single vehicle, which can be used alone (but usually isn't). Practically all of them feature some sort of remote control and are normally used for push-pull trains (the coaches are normal passenger coaches and don't contain anything needed to drive the train). Most have cabs on both ends, but some don't. What would be the proper term to use?
File:Bde 4-4 biberbrugg.jpg
File:MGB Deh 4-4 I bei Täsch.jpg
File:Npz portrait.jpg
--Kabelleger (talk) 22:42, 6 December 2010 (UTC)
thread_title:  Schlepptriebwagen 

message: The current text says both that a multiple unit is a carriage and that it is a whole train. This is confusing. Jdthood (talk) 19:27, 4 September 2017 (UTC)
thread_title:  Carriage or train? 

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thread_title:  A Commons file used on this page has been nominated for speedy deletion 

message: hello
what about Talgo system?
i think is not a Multiple Unit: they require a Locomotive, whit all driving, power device and motor in one heavy car (at head of train, at least)
and probably can work as a big-long carriage with any kind of locomotive: :commons:File:EN11273MilanoCLE.jpg
so i think talgo such RENFE_Class_130 and RENFE_Class_730 are not Multiple Unit.
then, why on Talgo and "Category:Electric multiple units of Spain" they are reported as Multiple unit?
--151.82.62.117 (talk) 22:31, 12 April 2019 (UTC)
thread_title:  Talgo vs. multiple unit 

message: ::::-- following from topic above --
Well, so you say "yes" to new article named "Distributed-traction train"; right? ...then i can't understand what is the problem about you have on this by adding "But it is NOT WP's role to invent what the name should be for it"; can you please explain better/with other words? (maybe i've just problem on understanding english).
Also, i think can be good to create ":Category:Distributed-traction train", for collect all distributed-traction trains, pointing for general reference on the homonim new article.
--151.68.28.76 (talk) 06:47, 18 April 2019 (UTC)
thread_title:  Proposal of new article and category named "Distributed-traction train" 

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thread_title:  Commons files used on this page or its Wikidata item have been nominated for deletion 

message: Multiple-unit train control was first used in electric multiple units in the 1890s.
The Liverpool Overhead Railway opened in 1893 with two-car electric multiple units, controllers in cabs at both ends directly controlling the traction current to motors on both cars.
The multiple-unit traction control system was developed by Frank Sprague and first applied and tested on the South Side Elevated Railroad (now part of the Chicago 'L') in 1897. In 1895, derived from his company's invention and production of direct-current elevator control systems, Frank Sprague invented a multiple-unit controller for electric train operation. This accelerated the construction of electric-traction railways and trolley systems worldwide. Each car of the train has its own traction motors: by means of motor control relays in each car energized by train-line wires from the front car, all the traction motors in the train are controlled in unison.
Reading it as it is currently phased it makes it seem like the multiple unit was in use two years before it was invented. I Like The british Rail Class 483 (talk) 16:17, 27 July 2023 (UTC)
replies: text: Read what you wrote again, specifically "all the traction motors in the train are controlled in unison" which was not the case for the example you give. Trainsandotherthings (talk) 22:42, 27 July 2023 (UTC)
thread_title:  How was the multiple unit invented after it had already been in service?