LAST EDITED ON Jun-04-03 AT 08:14 PM (EDT)
I've got some questions regarding Multiple Unit (MU) running of prototypical locomotives in the US, namely to which technologies and procedures were used and are in use today:Dear fellow simmer community,Some questions and thoughts regarding North American RR operations have accumulated with me over the past few months of exploring US routes and rolling stock in MSTS. As I am not at all familiar with the details of operations and methods due to the fact that I grew up a little too far away from it, where I got used to different rules and railway operation procedures, I dare bringing some of these questions forward in a series of posts. I think that your answers might also be of interest to others, be it that they too are not familiar with North American RRs, be it that they are new to the rails per se. The other topics are to be found in the following posts, which I decided to split in the sake of keeping each subject focused:Questions regarding geographical assignment of prototypical locomotives at http://www.train-sim.com/dcforum/DCForumID1/5338.html
Questions regarding prototypical speed limit policies for various train types at http://www.train-sim.com/dcforum/DCForumID1/5337.html
Quesitons regarding realistic scheduling of my AI trains on US routes at http://www.train-sim.com/dcforum/DCForumID1/5340.htmlNow for my questions regarding Multiple Unit (MU) running of prototypical locomotives:I understand that railroaders both sides of the Atlantic pond speak of MU (multiple unit) operations when more than one locomotive is used to move a train, which must be kept apart from dead-heading a “cold” engine, i.e. hauling an idling engine or an engine that is shut down, as pure weight and ballast in a consist pulled by another engine.Now the part which currently is interesting me is how the trailing engines of a MU consist are in general terms controlled today, and what different steps led to the current solution. Theoretically, there are several possible ways of driving MU consists.1) Probably the oldest approach was the one of staffing each engine within a MU consist with its own crew. This already allowed (usually) two steam engines to double head a heavy train, especially on steep grades. Logically, steam engines can hardly be remotely controlled, so all a RR needs to set up for this “manned” approach to MU is a set of communication rules among the crews of the different engines.
1a) Typically, these would have been a predefined set of whistle signals in the days before radio communications. While I know that such procedures were actually maintained by various railroads in my home country, I wonder whether a similar phenomenon could also be observed in the heydays of US steam operations.1b) Furthermore, I dare to ask if a similar scheme survived into the days of the early diesels, albeit I’d imagine that radio communications between the crews would have been introduced as replacement for whistle or horn signals among crews at about a similar time? If so, which types of engines on which RRs would have been MUed in such a way, and for which period?2) The more sophisticated approach to MU operations is the introduction of a means to actually controll all engines of a given consist remotely from the leading engine, thus making additional crews redundant. I assume this technology – which probably springs from electric trolley and interurban cars of the 1920s and 1930s, which are about the earliest examples of “true” MU engines I can dig out anywhere – would quickly become the preferred approach to MU by any RR, as the one-time investment in new technology is quickly offset by the savings on wages… So am I correct in assuming that MU consists with remotely controlled trailing engines are the norm in North America (excuse me if this is an obvious question, but I haven’t seen an explicit confirmation of this assumption on these for a yet)? If so, that leaves us with a whole array of questions on how exactly this remote controll is set up.2a) One possible ways is via a multifiber or coaxial cable connecting the various engines that transmits all necessary commands, inputs from the crew, alerts from the engines etc inbetween the leading engine and the trailing units. While this traditional system still is in widespread use in Europe, I wonder if it is also used with US locomotives?2b) The question above came to my mind due to the fact that the US seems to have taken a pioneering role in remotely controlling engines via radio signals, which is especially helpful on routes where mid-train or tail helpers are used. Two reasons speak for this technology: First, the longer a train, the higher the risk that signals travelling through these multifiber cables get lost or garbeled. Secondly, these cables are expensive, and in order to work with helpers mid- or end-train, these cables would have to be going through each and every freight car of the consist – which I doubt the RRs of North America would actually consider an option? 3) Assuming now that either remote controll via radio is the norm, or that both radio and multifiber cables are used (e.g. where no helpers are used and MUed engines always run next to each other up-front), that leaves me with the not so unimportant question of compatibility of various engine types and their MU installations. Is there a common standard for all of the US (and possibly Canada), across the board? Are there common standards for one specific engine type? Does each RR have its own standards? Assuming that an F7 is so different from a P42 Genesis (hope I got the designation right) that they simply can’t be MUed together, while a GP38 looks similar enough to go together with a GP40: Which different types of engines can be MUed together at all? So it all boils down to the following array of questions:
Which types of MU operations were historically used with which types of engines?
Which is the brief history of MU with remotely controlled engines?
Which families of engines can run MU together, which cannot?Hope this longish thread is of interest, I’m looking forward to your answers…Lukas a.k.a Swissie
(Edited for the links to other threads posted parallely)
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