Message Areas - "How Many Engines per Consist?"

Train-Sim.Com Message Areas

"How Many Engines per Consist?"

Email this topic to a friend
Printer-friendly version of this topic
Bookmark this topic (Registered users only)
Previous Topic | Next Topic Conferences General (Protected) Original message
C5129E (7 posts)
Aug-10-01, 04:05 AM (EST) "How Many Engines per Consist?" Can somebody give me a good equation to use when determining how many locomotives to use with "X" number of cars? I understand that most railroads set up a consist by the "required horsepower per ton" method and then add the appropriate number and type of locomotives. I also understand that this can very depending on the route and railroad, so if someone could tell me a good estimate to use for lets say, hhhhmmmm, Marias Pass for instance, I would greatly appreciate it. Thanks in advance! Alert Edit | Reply | Reply With Quote | Top
Table of Contents

Subject Author Message Date ID RE: How Many Engines per Consist? plainsman Aug-10-01 1 RE: How Many Engines per Consist? Curious Aug-10-01 2 RE: How Many Engines per Consist? plainsman Aug-10-01 3 RE: How Many Engines per Consist? Curious Aug-10-01 4 RE: How Many Engines per Consist? plainsman Aug-10-01 5 RE: How Many Engines per Consist? jimmccarthy Aug-10-01 6 RE: How Many Engines per Consist? plainsman Aug-10-01 7 RE: How Many Engines per Consist? jimmccarthy Aug-10-01 8 RE: How Many Engines per Consist? Curious Aug-10-01 9 RE: How Many Engines per Consist? plainsman Aug-11-01 10 RE: How Many Engines per Consist? Curious Aug-11-01 11 RE: How Many Engines per Consist? C5129E Aug-11-01 12 RE: How Many Engines per Consist? sniper297 Aug-22-01 13

Lobby | Topics | Previous Topic | Next Topic
Messages in this topic
plainsman (107 posts)
Aug-10-01, 06:05 AM (EST) 1. "RE: How Many Engines per Consist?" I think your question wants a simple answer to a very complex question. Horsepower is only a part of the concern (this enables the train to hold enough track speed to flow with the prevailing traffic of that road). Tractive effort (force) is needed to get a train moving, and lift it over a steep grade. Position of the locomotives within the consist is important, because the metal drawbar of the leading locomotives will break if too much force is applied (this is a dynamic concern, meaning the force changes due to operation of the engines controls, thus an experienced talented engineer will be able to keep these forces under control by use of slack and carefull throttle vigilance). Is the train going to make frequent stops or run unimpeded down the track? It takes a lot more locomotive to accelerate the train than to keep it moving. Is the locomotive a high adhesion model or a lower adhesion model. With the same 2000 HP and weight, the difference in performance of a model with 18% adhesion verses a model with 32% adhesion would be dramatic. With a 260,000 lb. locomotive, the difference would be 46,800 lb of tractive effort verses 83,200 lb. This performance differential is even more dramatic on wet or ice coated rail. Are your cars fully loaded, or are you returning empty coal hoppers?
Two SD90macs will easily move 40 loaded grain cars on flat routes in dry weather. Over the pass, the required lifting forces would break a coupler or drawbar, so you might need a Dash 9 pushing, and another Dash 9 in the lead? Then there is braking, how much brake force will be needed on the way down? There are a number of other factors as well, but this should give you some idea of things to consider, when you assemble your consist.
Bob
Remove | Alert Edit | Reply | Reply With Quote | Top
Curious (18 posts)
Aug-10-01, 02:12 PM (EST) 2. "RE: How Many Engines per Consist?" plainsman,Your very informative reply to C5129E's (any relation to R2D2 or C3PO?) question got me to wondering. What controls the amount of adhesion that a locomotive has? Obviously, the amount of hoursepower is mainly controlled by the size of the engine. But what besides the weight of the locomotive and the number of driving wheels (under whatever weather conditions) controls the amount of adhesion between the wheels and the rails? Thanks for your info. Remove | Alert Edit | Reply | Reply With Quote | Top
plainsman (107 posts)
Aug-10-01, 04:44 PM (EST) 3. "RE: How Many Engines per Consist?" LAST EDITED ON Aug-10-01 AT 04:46 PM (EST)Hi,
Up until the GP49, GP50, and SD50, adhesion was basicly a function of good truck and wheel design. The GP7 and RS-2 and SW1200 have about 18% adhesion. In a GP38-2 this has improved to about 22-24% by better design of these components. A U33C or a Alco 430 or a Baldwin AS616 would all fall in these ranges. With the GP49&GP50&SD50, the control of wheelslip was increased markedly, by using a computer to sense the advent of wheelslip, and to allow just enough to maintain maximum traction. The computer does this by making very rapid adjustments in the power input to keep the wheels from spinning too much. This technology has enabled dramatic improvement in adhesion. A GP50 would be in the 27-30% adhesion range and a SD75 or SD90 would be 32% or better (EMD claims better, but I think most railroads downrate the factory values). A C36-7 would be about 26-27% and a Dash 9 about 32% as well.
Hope this helps.
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
Curious (18 posts)
Aug-10-01, 06:43 PM (EST) 4. "RE: How Many Engines per Consist?" Hi,Thanks for the info. Since the rating used for adhesion is a percentage, and 32% is a good rating, does that mean that a Dash9's wheels are still "slipping" 68% of the time under the conditions used to measure the amount or degree of adhesion? Just curious. Remove | Alert Edit | Reply | Reply With Quote | Top
plainsman (107 posts)
Aug-10-01, 09:14 PM (EST) 5. "RE: How Many Engines per Consist?" The adhesion percentage is not the amount of time the wheels are stuck to the track, it is the % of the locomotive weight that can be used to drive the locomotive forward (or in reverse).
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
jimmccarthy (121 posts)
Aug-10-01, 09:40 PM (EST) 6. "RE: How Many Engines per Consist?" Adhesion percentage =
Maximum continuous tractive effort/locomotive weight X 100
Remove | Alert Edit | Reply | Reply With Quote | Top
plainsman (107 posts)
Aug-10-01, 10:06 PM (EST) 7. "RE: How Many Engines per Consist?" Hello Jim,
I think we just said the same thing. Since the poster didn't pick up the reference to tractive effort in the answer above, I thought that term might be confusing to him?
Thanks,
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
jimmccarthy (121 posts)
Aug-10-01, 11:09 PM (EST) 8. "RE: How Many Engines per Consist?" Yes you're right. You did say the same thing now that I read it again. Excuse me for wasting ink or electrons or whatever I wasted. Remove | Alert Edit | Reply | Reply With Quote | Top
Curious (18 posts)
Aug-10-01, 11:22 PM (EST) 9. "RE: How Many Engines per Consist?" Yeah, excuse me for wasting everyone's whatever was wasted. I'll try harder to pay closer attention from now on. Remove | Alert Edit | Reply | Reply With Quote | Top
plainsman (107 posts)
Aug-11-01, 00:21 AM (EST) 10. "RE: How Many Engines per Consist?" We are all having fun here and learning some physics in the process, not anything wasted in any of this!! All comments help us understand better.
Thanks for your interest.
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
Curious (18 posts)
Aug-11-01, 03:23 AM (EST) 11. "RE: How Many Engines per Consist?" Thanks for sharing your exceptional knowledge of the physics of railroading in general, and locomotives in particular. This forum definitely has been (and continues to be) a worthwhile learning experience. Remove | Alert Edit | Reply | Reply With Quote | Top
C5129E (7 posts)
Aug-11-01, 10:04 PM (EST) 12. "RE: How Many Engines per Consist?" Thanks for all the information! I also saw a posting by "Stein" in the MSTS forum called, "A Really Great Site-Check it Out". I took his advise and went to www.vcn.com/~alkrug/home.html where I found lots of informative information by a real life BNSF driver. There is a Train Force Calculator that you can download free from his website. Lots of great photos to look at too.
Thanks again for responding.
C5129E Remove | Alert Edit | Reply | Reply With Quote | Top
sniper297 (240 posts)
Aug-22-01, 12:32 PM (EST) 13. "RE: How Many Engines per Consist?" You guys make this too complicated. The correct formula is whatever gets you up the hill!

I think I can, I think I can - AW, #@$%&%*!30 log cars, 2% grade, 4 Pacifics? Nope. Remove | Alert Edit | Reply | Reply With Quote | Top

Lock | Archive | Remove

Lobby | Topics | Previous Topic | Next Topic