I finally got around to checking my N scale rolling stock for proper coupler height and weight. I was amazed to find that all but two or three of my cars were way below the NMRA recommended weight I added weight to get everything close to the NMRA weight without going over. With my rolling stock at the NMRA recommended weight, my consists have gone from 25 car freights able to climb the 2% grades of my layout, to consists about 1/3 that size. My question: is the NMRA recommended weight (0.5oz. + 0.15oz./in.) too heavy? Can anyone recommend a better criteria for N scale car weights? Thanks…Jim
Well, the whole key to the matter is “recommended”. These recommendations are based on both stability and tracking ability for the car in question, as well as providing the necessary heft to keep couplers together. In HO scale, I have invariably found that when I have trouble with mysterious derailments, the car in question is significantly under weight.
There’s nothing that says you can’t lighten them, though, if the heavier weight is causing you problems, and you weren’t experiencing any performance issues before.
The NMRA RP is based on HO scale experience before the days of free-rolling trucks. The RP did do several things in HO - it provided enough weight to make reasonable sprung trucks actually spring, allowed automatic coupling to work without the car moving away, and helped prevent string-lining on sharp curves. Note that the last two items apply to N and HOn3, as well as HO.
In HOn3 we have a similar problem to N. Car weights are even more all over the place due to some being made of brass, and some from wood or resin. But the tiny engines just don’t have room for much additional weight to enhance pulling power.
Although the RP for HOn3 says considerably more, a body of experience says that 1.5 oz for the typical car seems to be heavy enough, and more is not needed. Passenger cars, being longer, may need more. But the 1.5 oz is necessary to allow automatic coupling to work.
The key in N is probably going to be how light can you go before coupling and string-lining become issues. Increasing radius will reduce string-lining faster than increasing weight. Another trick to make light weight work better is to make sure all trucks are free-rolling. If a car won’t roll on its own down a 2% grade, it can’t be used until the trucks roll better. Some would even tighten the requirement to 1.5% grade.
Please report back on your experiments so we can all learn.
Fred W
Jim,
I am sort of puzzled by your 67% loss of train length on your 2% grades. What make of cars/trucks are you using? A friend has lots of Micro-Trains cars and they seem to have lots of friction due to the large plastic ‘pizza cutter’ flanges that came on them. He converted all of them to Atlas metal wheel sets that are made specifically for the Micro-Trains truck… He really has no grades, but he got a lot better rolling out of the cars and can pull longer trains on the groups modular layout.
Myself, I am in HO and I do weight my cars to the ‘RP’. I like the ‘heft’ and more positive coupler action. My P2K GP’s will handle about 15 cars on a 2% grade at the club. Usually two engines will haul a 25-30 car train up the curving(33" radius) ‘hill’ on the club layout with no problem. A couple of weeks ago I had a pair of P1K GP15’s handling a ‘buffer’ car and 24 Ethanol tanker around the layout.
Jim
what is “string lining”?
I havent ever read this term before… .
You say “consists” of 25 cars “Consist” refers to the locomotive(s) pulling the 25-car “train”. How many locomotives are actually pulling the train?
My standard is add a loco for every 10-15 cars (for 4 axle engines), and 15-20 cars for every 6 axle engine. In your situation of a 25 car train, I would have at least 2 engines pulling that train, (depending on the grade I might add a 3rd).
One of the things you get with the weighted cars that wasn’t mentioned, is momentum. You get more of the feel of the weight of the train.
Jim,
I am sort of puzzled by your 67% loss of train length on your 2% grades. What make of cars/trucks are you using? A friend has lots of Micro-Trains cars and they seem to have lots of friction due to the large plastic ‘pizza cutter’ flanges that came on them. He converted all of them to Atlas metal wheel sets that are made specifically for the Micro-Trains truck… He really has no grades, but he got a lot better rolling out of the cars and can pull longer trains on the groups modular layout.
Myself, I am in HO and I do weight my cars to the ‘RP’. I like the ‘heft’ and more positive coupler action. My P2K GP’s will handle about 15 cars on a 2% grade at the club. Usually two engines will haul a 25-30 car train up the curving(33" radius) ‘hill’ on the club layout with no problem. A couple of weeks ago I had a pair of P1K GP15’s handling a ‘buffer’ car and 24 Ethanol tanker around the layout.
Jim
It’s my experience that for H0n3 the NMRA weights are too heavy. Blackstone cars have only 65% … 85%. And it works! My H0 roster has the NMRA weights.
Wolfgang
String lining is when you pull a train around a curve, and the train tips over to the inside of the curve. The cause is light cars and sharp curvature.
It happens to the 12":1’ guys, too. Roadrailers are notorious for this…
Hey Fred:
As you requested. here’s what I leaned. By the way, Thank You for your reply. I picked out 13 of the cars I had brought up to NMRA weight seeing to it that all categories were represented (i.e. box cars, gondolas, etc.). All cars had either Micro Trains or Atlas trucks. I gave them the will they roll down a 2% grade test you suggested. Only two of them would do it and they were struggling. Most would after being nudged, roll only about a foot and stop. Investigation showed that of the 13 cars, four had Micro Trains trucks with large flange wheels. I’m using Peco code 55 track. I replaced the wheels with some new Micro Trains low profile wheels that I had and the result was dramatic. The cars when released rapidly accelerated down the ten feet or so of 2% grade and continued another 20 or so feet across the flatland. Both the grade and the flatland have 15 inch radius curves in them. The others had wheels that were in need of cleaning. After cleaning, their performance matched the result described above. One car with Atlas trucks had a bit of flash on the axle that was barely rubbing on the coupler box. I just coupled up all 13 of the cars behind my MIcado and it ran the entire layout without once spinning or bogging down. Originally, I was running 24 car trains with this and after bringing everything up to weight it would only pull 6 or so cars and that was a struggle. My conclusion is that I had frictional drag on all my cars due to flanges and plain old dirt that I had been getting away with at the lesser weights. Some of my cars are flat cars, gondolas and boxcars with operating doors. They were only about half of the NMRA weight because (I assume) the manufacturer anticipated the end user would be adding loads to them. Adding weight exacerbated the frictional drag to a great extent and resulted in a load that my engine could not pull. I will get on with the remainder of my r
Thanks everyone for you replies. I posted a return to Fred reporting what I have learned thanks to your inputs. Jim