How does double heading work in real life?

[buttman]

I am assuming that, in real life, there must be some kind of system that actually allows the lead cab to pass on inputs to each supporting engine so that they all use the same throttle and braking. Can someone explain briefly how the technology works? Does simply coupling the two trains also allow the systems to communicate so that master/slave controls can be enabled or does someone have to get out and hook the trains up with some kind of supporting connection to do this?

Now going beyond that, what's the realism case for steam engines double heading in Railworks? How did this get done back in the days? Did the engineers communicate with hand signals or something?

Just curious how stuff is done in reality.

Thanks in advance.

[pwillard]

FROM WIKIPEDIA:

All North American locomotives, including export models, use a standardised AAR electrical control system interconnected by a 27-pin jumper cable between the units

How universally *true* that is unknown by me.

[buttman]

Ah I had looked over the wikipedia page but didn't pick up on that bit. It looks like Steam engine double heading was a manual process and, as one might expect, depended very heavily on the operators of each engine to be working together well, as the result of engines running at different speeds has been the cause of a number of accidents. Apparently part of the reason for making locos larger and larger was in part to phase out the need to double head them.

[Chock]

Hi, first post on this forum for me, and hopefully a helpful one...

Modern North American locomotives are now starting to use computer controlled systems to operate more than one engine in combination, and of those systems, probably the most widespread one is made by General Electric, that being 'Lococontrol'

You can read more about Lococontrol here: http://www.getransportation.com/na/en/o ... stems.html

There are other similar systems in use in the US besides Lococontrol, such as Canac's computer system which is very similar to the GE one, however, Lococontrol is by far the most commercially successful, since UP use it, as do BNSF and most of the other big players in the US freight train business. Such systems require quite a lot of expensive kit to be installed though, so not all locos have the necessary hardware fitted, even at well-funded major railroads. Prior to all that fancy computer malarkey, simpler connections and the use of radio was generally the way things were done (and still is in many cases). Before radio was widely available in trains, the train whistle or horn was used to signal various power and brake settings to the other locomotive.

These days, double-heading is quite often being superseded by the use of distributed power, where you have locos in the middle and at the rear of the train; the computer sophistication available via systems such as Lococontrol means that the power and the brakes can be applied more effectively in such set ups, which means greater fuel economy and more efficient starting and stopping. There is also far less stress placed upon the couplings when using distributed power, as well as less chance of a 'stringline derail' when a long freight train is negotiating a curve, since the train is driven from several points throughout the consist, instead of being pulled solely from the front.

Al

[buttman]

Hey Chock, that's a really great post. Thanks a lot for adding.

When I asked about double-heading, I was referring to any configuration in which more than one engine is powering a train, so whether both are in front or spread out, I didn't even realize that was a distinction.

Can I ask where you get such intimate knowledge from? I assume you must work or have worked in the field?

[Chock]

Nah, I'm just and enthusiastic amateur, interested in railways and stuff (both HO scale models and simulations such as MSTS, Trainz and Railworks on computers, and mostly US stuff despite me being from the UK). Thus I tend to do a lot of research on the subject in order to model thing as accurately as I can.

As far as distributed power is concerned, one of the nice things about HO scale models these days is that with DCC, that kind of operation can actually be simulated on a scale model railway, although actually having the room to create a train of that kind of length in 1:87 scale is of course another matter. Whether we'll see that level of realism in Railworks remains to be seen though, although it is at least theoretically possible. Ironically, the now rather older MSTS is actually quite realistic in terms of multiple engine operations, so I still find reason to crank that up in spite of its age.

Al

[TVRRMAN]

I think I'm going to chime in on this one also.

On the issue of double heading, it depends on the type of train, and also the motive power. During the days of steam engines, double heading steam engines involved both engines being manned. for this to work, they used whistle signals. When radio and PRR's trainphone systems appeared, the whistle signals between engines disappeared. Three short pulls on thew whistle chord was "reverse when standing. I have a chart around here somewhere. one Short pull was stop. another signal given off was one short and a long, which told the crew to look for leaking or stuck brakes.

on steam powered passenger trains, most shots I have seen of double or triple headers had all power on the lead (this made it easier to cut them off as needed.) Freight on the other hand, may have had two engines, one forward and one "bringing up the markers," or even one on the lead and two at the rear. on the PRR's Shamokin branch, where 9000 ton ore drags were the norm, teams of I1s / I1sa 2-10-0's operated in pairs of two at the lead and two "bringing up the markers" to drag the trains from Sunbury PA to the Lehigh Valley interchange at mt. Carmel PA.

When early diesels came around, "MU" Capabilities became possible, although there is still word that early first generation diesels could only be MU'ed to models by the same manufacturer.

Hope this answers a little more.