i use n scale and have noticed my locos have trouble with spinning wheels when going up an incline and slipping while going down the same hill. the inconsistant speed and constant jerking and stretching of the train is causing derails and its frustrating. will adding an additional loco or two in a consist help resolve this problem? is there an equation for number of cars a loco can pull (eg. 8 cars for every one loco…)?
Out of the box each loco’s pulling power is different. Presumably several of the same type locos by the same manufacturer should have similar pulling power, but different types and differnent manufacturers will be different. Some locos pull better due to weight, others have traction tires, gearing can make a difference also.
Yes, just like prototype railroads, adding locos will mean you can pull longer trains. You can put them at the head, add a helper in the middle or a pusher at the back. Problem is with DC is getting all your locos to go at the same speed. Two (three) locos that are closely matched in speed can be used together at the front of the train, however putting one further back that is not well matched can cause problems.
This is one area where DCC comes in very handy. You can speed match your locomotives. I’m not in DCC to give you all the correct terms, but it can be done.
Good luck,
Richard
You don’t mention just how many cars you are pulling w/ that single engine and also how steep a grade. It sounds that you may be just running too many cars up a grade that one engine cannot handle. As said, the type and manufacturer of the engine will depend on the tractive force/ pulling power of each used. Try running 2 locos in consist and you should be fine.
I’m going to approach this from two angles, what the prototype does and my personal modeling experience.
First, the propotype:
- Every locomotive has a tonnage rating - how much tonnage it can take over an entire division. Some railroads based this on an arbitrary number of cars at XX tons per car.
- More than that tonnage would require doubling the steepest hill (taking the train up in two parts) or assigning a helper to that hill.
- If the whole division consisted of a series of grades (or one continuous grade, like the BNSF from Needles, CA to Flagstaff, AZ) most trains would require two or more locomotives. Current BNSF practice puts up to four units on the head end, plus pushers if necesssary.
Then, my layout:
- My JNR main line has grades up to 2.5%. If the road loco can’t handle the usual train I either doublehead or assign a pusher. Pushers are available for any train that may need them.
- My coal-originating shortline assigns teakettle tank locomotives on the basis of one drive axle per two trailing axles, so doubleheaders are normal and two plus a pusher are not uncommon. That’s dictated by 4% grades (compensated to 3.5% on 350mm radius curves.)
Back in the day, a Norfolk and Western coal drag might have doubleheaded 2-8-8-2s pulling, and another leaning on the rear coupler of the heavily-built steel caboose. At 10MPH, that would be just about 15,000 hp and close to 450,000 pounds of tractive effort.
Chuck (Modeling Central Japan in September, 1964)
When you say spinning wheels going up an incline, is this with a single loco or with consisted locos? If it is with consisted locos, then the either the engine speeds are not well matched, or one loco is heavier than the other. So a fast light engine will spin its wheels trying to push a heavier slower engine uphill.
Also, what do you mean by slipping going down hill? Sounds to me like the weight of the train is pushing the engine down the hill. What percent grades do you have?
As Chuck has said, it isn’t the number of cars that the trainmaster plugs into the formula, but the rated tonnage for any one engine over the division’s rails that counts. The trailing tonnage, that is.
I think your trailing tonnage, if the loco’s drivetrain is healthy and tight, is the problem. Not necessarily too much or too little of it, but the condition of it. Maybe even the condition of the rails, themselves, too.
Cars that come out of a box don’t necessarily perform optimally. Some have serious amounts of flashing and other imperfections in the trucks that make revolving axles tough work on a locomotive ahead of them. There is a ream for the bearing/axle-end recesses in rolling stock trucks, and it is called simply, “The Tool”. I believe it can be had at a well-appointed model trains hobby shop or from Micro Mark.
So, that’s problematic/sticky bearings. Then, there are the couplers. Oooooohhh…the couplers!!! Some are wonderful, some best dumped while holding one’s nose. There can even be problems with the way they are mounted. Often the cars stretch and compress like caterpillars around their sloppy couplers. If you are trailng about 30 ounces of weight in cars and they accordion back and forth, they might give the valient locomotive up front untold grief either up or down grades.
What I would urge you to do is to find the five or six best cars you have, all with free-spinning axles in every truck, and with well-mounted quality couplers that swing freely without catching in a nice wide arc, and then hitch them to your engine and trial it over the hump. You start with one car, do the hump, watch both items. Add one more car to the first, repeat observation trial. Repeat, repeat until you may notice one car seems to affect the engine. Watch for a change in performance of the kind to which you object. One car will make the difference. Is it tha
How steep is the grade? Grade is normally measured in %, that is how far it rises (or drops) in how far it goes down.
A very steep grade is 4%, that’s a 4" rise in 100" of run or about 4" in 8 feet, two inches in 4 feet.
A better grade is about 2% or less, that’s 2’ rise in 100 inches of run or 2" in 8 feet, 1" in 4 feet.
Since your engines are slipping going UP and DOWN the grades, that tends to indicate you have very steep grades and it may not be an engine problem at all, but a layout design problem.