BaltACD: Beaulieu told me that: "Each of the up to 4 locomotives controlled via Locotrol(DP), can control further locomotives via MU cables." From your example this train has three (3) DPU consists plus one (1) lead. If my understanding is correct, how many locomotives are maximum LOCOTROLLED within each of those three? I see two (2) consists with just three (3) locomotives (ie..< 4) but the end of train consist has five (5) which is > four (4)?
All i'm really trying to get an answer to is: What are the maximum number of consectutive locomotives, in DPU mode, that can be controlled by the lead? I think the answer is: no > four locomotives in no > four consists behind the lead; is that correct?
Then I'm still confused. If only UP TO FOUR (4) consecutive locomotives can be controlled via LOCTROL, then how could a train have five (5) in the midtrain DPU w/o a crew? How were these 5 locomotives operating?
CSX Rules limit the maximum number of engines in a engine consist to 12 engines. Working, isolated or dead - the maximum is 12. You will see these kinds of engine consists on trains destined major locomotive shops - the trains wil normally have only one or two engines operating - the rest are out of service for various reasons headed to the shop for repair. You may see a large number of engines on trains originating at the location of a major locomotive shop, those engines will normally be set off at terminals along the route of the train.
Maximum allowed train tonnage, under CSX Rules, was the tonnage that was rated for 2 GE AC's + 1 Dash-8 over the ruling grade for the train. Train was permitted to have a maximum of 27 powered axles. (AC's counted as 9 axles)
When you get into territory where Helpers (or Distributed Power) is required then you begin to get into 'trailing tonnage' restrictions that dictate where the additional power is placed in the train.
Fun with engines!
Never too old to have a happy childhood!
A locomotive 'consist' is the "preferred" word for what DPM and generations of railfans termed a 'lashup' -- a set of MUed locomotives responding to the control signals from its 'leader'. Locotrol has four separate controls, each of which can then control the leader of a set of locomotives, and of course the logical place for additional sets of locomotives is where DP puts them, distributed in the train (the cars are, confusingly enough, also often referred to as the 'consist' but that's a different consist!)
The number of locomotives in a MODERN consist is usually limited by rule (which in turn is written partly with an understanding of maximum number of powered axles, load on part of the train, etc. as just observed). BUT, as noted, the MU control can technically control a larger number of individual locomotives. Back in the bad old days of 1750hp maximum single-engine size, if I remember correctly, UP used to run as many as 15 units 'in multiple'. How many of those were isolated during part of the trip, or being moved to balance power, I don't know; I was not there. But Don Strack or someone like him will know.
So the answer is different depending on whether you're considering the maximum locomotive-consist size as being determined by operating conditions, or by the technical capability of the MU and DP systems. You'll get different answers, but the one limited by train and handling characteristics is probably a better one.
Just because you see multiple engines in a DP consist doesn't mean all may be working. One of our manifest trains normally runs with 4 engines in the mid-train consist. It normally sets out the entire DP set and cars behind it at an intermediate terminal. Often only two, sometimes one, in the DP consist are working. The rest are shut down/idling (depends on weather) for fuel conservation. It all depends on the train tonnage for how many engnes are actually running (producing power) on any train.
Jeff
Fictional Train -
Lead Locomotive Consist (4 units in MU with T&E Crew on lead engine)80 carsDPU Locomotive Consist (3 units)80 carsDPU Locomotive Consist (3 units)80 carsDPU Locomotive Consist (5 units)
The DPU consists are controlled by the crew on the lead locmotive.
beaulieu A locomotive "consist" can be any number of locomotives up to the maximum number that can be reliably controlled via the MU cable.
A locomotive "consist" can be any number of locomotives up to the maximum number that can be reliably controlled via the MU cable.
The portion of this statement "that can be reliably controlled via the MU cable." is incorrect.
The thing that limits locomotive consist size is some combination of drawbar (knuckle really) strength and Track Train Dynamics.
Grade C knuckles are rated for 240,000# of draft (pull or tension). Grade E is 360,000#. Given either limit, and given the ruling grade, and given maximum low speed TE of the consist, it is fairly simple math to figure out consist limits. In fact they are usually published in subdivision special instructions.
The Train Track Dynamics issues are more complicated mathmatically but the limit here is usually buff or compressive forces. The basic idea here is that under high buff loading it is possible to shove a wheel flange over the rail or roll the rail over. Again restrictions will be published in the special instructions.
The most power I ever saw on one train was the SP "oil cans" from Bakersfield area to the LA area on the loop at Walong. They had 4 SD 40 units on the point, 6 more cut in, and two more on the rear to climb to Tehachapi. I suspect the rear helper cut off at Tehachapi and the swing helper went through for dynamic braking on the 2.2% descents.
Each unit would have been rated for about 1100 tons on the 2.52% equavalent ruling grade (2.2% UNcompensated) so train could have been 11,000 tons or 83.6 cars given that power. My recollection is that the train actually operated with 80 cars.
SP SD 40's generated 90,000# of TE, so 4 of them were 360,000#, so we can safely assume grade E draft gear and knuckles.
It is all physics!
Mac
VGN Jess Thank you. So when I saw 5 locomotives as a midtrain DPU, there had to have been an Engineer and Conductor in the 1st of the 5?
Thank you. So when I saw 5 locomotives as a midtrain DPU, there had to have been an Engineer and Conductor in the 1st of the 5?
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Nobody is on the DPU units.
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A locomotive "consist" can be any number of locomotives up to the maximum number that can be reliably controlled via the MU cable. What the statement of 4 locomotive consists means is four sets of locomotives. Only 4 additional locomotives can be controlled via Locotrol (current version is now referred to as Distributed Power). Each of the up to 4 locomotives controlled via Locotrol(DP), can control further locomotives via MU cables.
Wikipedia says: "Most systems use lead and middle of train locomotives, but up to four consists can be controlled from the lead unit. My questions are: 1) does that mean only four (4) locomotives connected together (either mid train or end of train) can be controlled from the lead engine? or 2) could I have, say, six (6) mid train and four (4) end of train locomotives controlled by the lead? I guess I am confused by the word "consists"; is each locomotive a "consist"? I have seen pictures of 5-6 locomotives as a mid train DPU and didn't know (because there more than four (4) whether there were LOCOTROLLED or had a crew. Thanks.
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