I've been on a bit of an MU kick as of late, and a thought occured to me for potentially operating dividing/through passenger trains. I understand that most current MU's use WABCO N-Type multifunction couplers, but it could be possible for an AAR coupler to be fitted in a "swingdrop" position like on certain British passenger cars. I've also seen numerous instances of older MU trains being towed by a conventional locomotive, yet seemed to be hauled stock rather than "dead units". Think of it like a train of Arrows running on the old New York & Long Branch Railroad, but rather than having the passengers transfer to unpowered passenger cars, a fully diesel-powered ALP-45. This removes the process of changing engines at electrification endpoints (just adding a locomotive or letting it run off), and still allows for the benefits of EMU power where there's third rail/catenary.
Is it possible that MU consists like Silverliners, Arrows, and Metropolitans could be used as passenger cars nowadays, pulled by a conventional locomotive? If so, would it also be possible to fit a swingdrop WABCO N around an AAR coupler and connect it to an loco's electrical plant?
Also, can someone please explain what exactly an MU trailer is?
First, answering your question. An mu trailer is car without motors, but with couplers and wiring permitting it to be used between motor cars without interrupting the control ability for the engineer in the front of the leading motor car to control motors and brakes and possibliy doors in cars behind the trailer. If the car also has controls to allow use as a the lead car, being pushed by the cars behind, then it is usually called a control trailer. There are also cars called "blind miotors" which have motors and no controls.
For many years, possibly as early as 1914, until at least 1952, there were two New York Central commuter runs, from Peekskille to Grand Central Terminal in the morning that used mu cars hauled behind steam between Harmon and Peekskille. The particular mu cars were equipped for steam as well as electric heating, and the specific Pacific locomotives had generators for providing lighting power. The longer distance trains from Poughkeepsie did not use mus and changed engines at Harmon, as did all through trains.
So the MU's were equipped with the same heating/lighting systems as the locomotive, as well as normal couplers I'd assume given the time period. So if modern MU's were equipped in such a way, they could be pulled. Thanks for the info by the way, I had no idea the Central did this practice for that long with it's commuter trains.
Also, thank you for clearing that up. It seems that trailers are the MU equivalent to a locomotive snail, having electrical or even control systems in place, but no traction motors. Would...that technically disqualify the RDC-9's as being trailers?
Last question for now, if trailers are used in between two powered units, would that include the M4 and M6 cars used on Metro North? Unlike the previous Budd-built M1/2/3 cars (and most EMU sets from what I know), the 4's and 6's are built in sets of three, meaning that the middle car must not have a cab. Does that mean the middle unit lacks traction motors too?
In a similar vein, when South Shore first obtained trackage rights over IC into Randolph Street Station, the pre-Insull wood cars were hauled by IC suburban steam locomotives north of 115th Street. Since South Shore completed its re-electrification at 1500 volts DC before IC began its own electric service, the Insull cars were also briefly hauled by IC steam power north of 115th Street.
Metro North does not currently operate trailers, those middle cars are "blind motors."
Trailer: No motors, but wiring to insure full train opeation from lead car. Uusally also without controls.
Control trailer: No motors but full control equipment.
Blind Motor: Motors but no control equipment
Motor: Motors and control equipment.
On Metro North, the few "Singles" (if any left) have control equipment at both ends. The normal "married pairs" and "threesomes" have controls on the two ends of the complete set only.
The old classic D&LDW mu cars were married pairs, but in this case one trailer was married to one motor car. Control arrangements as above.
One interesting control trailer is car G at the Shore Line Trolley Museum. I was built around 1988, I think by Jackson and Sharp, as a normal coach to run behind Forney steam locomotives on the Manahttan Elevated. After electrification, it became the pay car for the elevateds, had baggage-car doors added to its sides, and now is occasionally used to form an elevated train at the museum with BMT wood open-platform gate cars.
So...if I were to compare these to diesels...
Trailers were conventional cars that work off the power of the the powered unit
Control trailers were NPCU's
Motors were A-units
Blind Motors were B-units
That makes me wonder if any trailers just kept the traction motors for electric lines that had any difficult grades.
They would then be "blind motors" comparable to B-units, and not trailers.
There is absolutely no case in North America of any electric railroad having blind motors (or any motor cars) that used their motors only for grades and not for relatively flat portions of the line.
But there are cases of mu trains' operators cutting out the power of one or more cars and motoring on with the rest because of inadequate power in the trolley line, in other words inadequte generating station or substation power. Cases included Indiana Railroad specials onto connecting interurban lines and certain multi-car fantrips, all using the "high-speed" lightweights. In these cases, yes, the motor car with the motors switched off effecively becomes a trailer.
They would then me "blind motors" and not trailers.
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