I have reviewed the NMRA recommendation for weight which I understand. My question is does the length of the car include the couplers or not, or doesn’t it matter?
Appreciate the help
Well, the way I do it is just to measure the length of the car, not including the couplers. For example, the length of a boxcar is the length of the box itself. To me that’s close enough. I’m not going to worry about a difference between two otherwise identical cars, one of which having a cushion underframe with extended couplers, and the other without.
You do not need to factor in the length over the couplers. If you do, just be consistent. Factor in the length off cars over the couplers. Myself, I basically round off the length to the nearest scale 5 ft’ The idea is that you try to get all of your cars to weigh the same in proportion to the length.
A lot of folks mention that they weight their cars to something less as modern HO models have better free rolling trucks. I still use the same basic NMRA system. I like the way they ‘roll’ when switching. BTW, I also use metal wheels in all of my cars.
Jim
Consistent and close is what matters, although I have plenty of open hoppers without loads that are well under the NMRA rcommended weight, yet give absolutely no trouble, even when purposely doing bad things like stopping the train in the middle of a curve and then jerking the throttle open to full speed.
–Randy
I’ve only ever added weight to my fleet of Athearn Bombardier cars and a few hoppers.
Keep in mind the NMRA recommended practice is not a standard just a recommendation. It was also drawn up in the early fifties or late forties. Track was not nearly as good as it is today. Instituting a program of checks and maintenance to your rolling stock and track work is more important then weight. A heavy car will derail just as easy as a light car with out of gauge wheels and bad track. Unless the car is carrying a load then I never add weight over what came with the car. I would rather have my locos pulling 40 light cars over 10 heavy cars.
Pete
The NMRA weighting recommendations were largely driven by experimentation by the late Ed Ravenscroft. He wanted cars to roll consistently and react properly to the air retarders of his hump yard. The blast of air could have blown a too-light car back up the grade!
I found out the hard way that cars can, in fact, be too light. Even with nothing else wrong, it takes weight to press the trucks down to ride evenly on the rails. OTOH, it may not require as much weight as those half-century-ago axles and bearings required.
Chuck (Modeling Central Japan in September, 1964)
Whenever I have a problem with a car derailing on turnouts or intersections, the first thing I do is check the car’s weight. Almost invariably, they are too light.
I keep lots of washers on hand for this purpose.
According to the RP, including or not including the couplers would make about 1/4oz difference. I’m pretty happy if my cars come within 1/4oz of the RP, I don’t worry about being more exacting than that.
As has been pointed out, weighting cars to the NMRA recommendation will reduce the number of cars up a grade compared to lighter cars. The extra weight will not make that much difference in the number of cars on level track; the free rolling ability of the trucks will have more impact in my experience.
NMRA RP weight enables truck springs to work properly - if you use sprung trucks (I much prefer sprung trucks). OTOH, rigid frame trucks of soft plastic can show wear in the journals - the more weight, the faster the wear.
Another area weight makes a visible difference is in the “slinky” effect. For some reason, NMRA RP-weighted cars don’t have nearly the propensity to go into “slinky” mode that lighter cars do.
And RP-weighted cars couple and delay uncoupling much better than lighter cars. I’ve seen too many cases of trying to couple very light cars on free rolling trucks - they push each other around instead of coupling. And when performing the delayed uncoupling push, light cars tend to separate at inopportune times more than properly weighted cars.
Bottom line: a consistent weighting scheme is needed for reliable operation, whether it is the NMRA RP or something lighter. I personally favor the NMRA RP because longest possible train up a grade is not a priority for me; the other factors I have listed are more important. I am willing to modify my locomotives to get more car pulling capability. Others have other priorities and preferences, and for them a lighter weighting scheme might work
AH HA! Thank you, I’ve bee hunting for the article I saw that in. Interesting topic.
One other side of weight: In looking at a Ringling Circus train, it may be required for me to go over the weight RP, so that the cars become heavier and less likely to lift up and stringline. A proto-length train is an actual 70ft. A friend of mine has run Intermodals of close length and his cars all tweigh in between 10 & 12 ounces which I;m sure is a bit over the RP.