behillman wrote:

For what it's worth,(and to answer my own question about scale
weights versus NMRA weight recommendations), I did a couple of
calculations.

I calculated 2 HO cars, 1-38ft wood reefer & 1-50ft steel boxcar. I
took the reporting marks data off the car-sides and computed scale
weight, then computed the NMRA weights according to car length, as
follows:

38ft wood reefer, total prototype loaded weight=136,000lbs.
Scale weight=136,000lb./(87.1 cubed)x16 = 3.2930 oz.
NMRA weight=5.25"(length)x.5 oz./in. +1 = 3.6250 oz.

The 136,000 pounds you cite appears to be the Gross Rolling Load (GRL) for a car with two trucks having 5" x 9" axle journals. GRL is the sum of the light weight (LT WT) of the car plus the load limit (LD LMT). Thus, your scaling would include the weight of the load. The LT WT of this 38' Reefer would have ranged between approximately 50,000 and 54,000 pounds.

50ft steel boxcar, total prototype loaded weight=168,200lbs.
Scale weight=168,200lb./(87.1 cubed)x16 = 4.0728 oz.
NMRA weight=6.875"(length)x.5 oz./in.+1 = 4.4375 oz.

The 168,200 pounds should be 169,000 pounds if you are using the GRL for a car with trucks having 5 1/2" x 10" axle journals. The LT WT for this 50' Boxcar would have ranged between 50 and 54,000 pounds.

The maximum weight of the ice in a reefer's bunker was included in the LT WT of a reefer which accounts for the similarity of the LT WT ranges for the 38' reefer and 50' boxcar. For what its worth, a 40' steel boxcar having 5 1/2" x 10" trucks would have a LT WT between 42 and 45,000 pounds. Its GRL would have been 169,000 pounds - the same as your 50' boxcar because both had trucks of the same size.

In both cases the NMRA weights exceed the scale loaded-weights by 9%
to 10%.

Oh? You are measuring cars which were always loaded to nominal capacity. In 1954, when the average nominal capacity of America's freight car fleet was 52.5 tons, the net ton miles per loaded car mile was only 31.3 tons, or the average car was loaded to only 59.6% of the average car's nominal capacity. Further, your scaling does not factor in when the car was empty.

Referring to the NMRA car weights practices, it states the various
reasons for their recommended weights are, including, railhead
contour, wheel contour & proper truck-springing and equalization.
I'd wonder if Proto 87 standards would affect the NMRA results? (I
have used the NMRA weighing standards for many years.)

In referring to one of my perfectly-scaled freight-cars I could
say, "Everything is to perfect scale, including it's weight." You
think that might help it sell?

Nope - not unless you have scale Light Weight plus individual scale Loads in terms of weight for every time you move your model car. Right now, models are all empty, and the modeled weight of those cars far exceed the Light Weight of the "real thing."

Tim Gilbert

The concept of "Scale Weight" really is a dead end, in my opinion. Scale
weight means nothing to our operations - but "scale mass/momemtum" would be
great! It would be great fun to have a car that actually resisted the
pulling forces based upon its supposed weight, and that likewise would
demonstrate momentum once rolling. But, friction does not scale, so to
achieve such action/reaction in our tiny models, it seems they would either
have to be very heavy, or have someway to interconnect the axles to a large
flywheel inside the carbody, or perhaps have a powered truck that acts as a
momentum device (which would necessitate its own DCC decoder, all cars have
an address, a software that peeks at the locomotive motor speeds, a way to
determine actual velocity vs called for velocity, a way to simulate the
application of train brakes and locomotive brakes, blah blah blah). In
either case, however, the mechanics of the task would pretty much rule out
scale appearance, I would think. Perhaps one could do without the DCC
decoder and address, but a way for the car to determine its speed and to
simulate the momentum would still be a pretty daunting task. And likely very
difficult to hide amongst the sideframes of an archbar truck.

Likewise, if carloadings were commonly only 50-60% of capacity for the era
applicable to this list, would it be necessary to "tell" the momentum device
at each loading/unloading the weight of the car in transit? All this likely
could be achieved, but at what cost to the final car? And does it adequately
truly add that much to the enjoyment of our model railroads? Or would simply
adding momentum effects to our locomotives be more than adequate to
compensate for the lack of true mass effects? While I would LOVE to be able
to "kick" a car down a spur, or have an authentic looking humpyard, it
appears that the cost of getting there is a lot greater than the perceived
benefit.

So, in final answer to your query whether it makes sense to market your cars
as "scale weight", it appears that extra detail would not only be difficult
to achieve for an empty car, but that it is meaningless to good operations
anyway. My experiences indicate a heavier car works better and remains on
the track better than does a lighter car. I don't know whether this is
because some of the limiting factors for scale operation at scale weights
include non-scale friction that permits a wheel flange to climb the railhead
in preference to staying on track when the car is lightly weighted, or
whether it is our very sharp curves that scrub speed and tracking
simultaneously from our models, but in my experience heavier cars have
operated best for me. Some of my best operating cars are unicast urethane
models that are quite heavy, certainly much heavier than the NMRA
guidelines, that seem to never derail and never stringline. They seem to
stay anchored to the track, and also seem to be easier to couple to and
uncouple to using Kadee couplers. They are also easier with which to use the
delayed uncoupling feature, as when pushing them they tend to stay in close
proximity to the pushing coupler, rather than "bouncing around" as some of
my lighter cars do.

Anyway, those are my thoughts. Hope the length and content are not
considered way too far off-topic.

Tom Jones

Tom Jones III wrote:

The concept of "Scale Weight" really is a dead end, in my opinion.

I think this sums it up.

But, friction does not scale, so to
achieve such action/reaction in our tiny models, it seems they would either
have to be very heavy, or have someway to interconnect the axles to a large
flywheel inside the carbody, or perhaps have a powered truck that acts as a
momentum device . . .

I think Tom has it backwards here. As we saw a few days ago, the NMRA weights are not inconsistent with a loaded car. So the challenge is to duplicate an EMPTY car, i.e. to make the car act LIGHTER. And as Tom says, friction doesn't scale, and in models it fails to scale in the adverse direction, which is to say, the friction is too big. That's another reason we need LESS resistance, not more.

My experiences indicate a heavier car works better and remains on
the track better than does a lighter car.

This is what most people find. But I don't think it has anything to do with scale weights; rather, as Tom mused, with model wheel-rail forces, sharp curves, etc.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@signaturepress.com
Publishers of books on railroad history

I must not have made clear my thoughts - even an empty car prototypical has
a "different" apparent motion and observed momentum than does its model.
This is because of the different relative masses. So, I agree - less axle to
frame friction would help - but there is no real way to achieve this end.
The alternative is to increase the apparent motion and observed momentum of
the model. This would require faking those attributes of the prototype, as I
discussed in my original post. It can be done, but the results are not worth
it.

Whether the weight is consistent with the NMRA guidelines or not doesn't
really matter. What matters is that the model react and appear as the
prototype would. I just don't see how we can achieve that with the small
masses we are working with here unless we fake it by enhancing the apparent
motions and momentum.

Tom

Tom Jones wrote;

"It would be great fun to have a car that actually resisted the
pulling forces based upon its supposed weight, and that likewise
would demonstrate momentum once rolling."
*****************************************************************
Response;

I believe John Allen did that "way-back-when", when he built a boxcar with a flywheel in it attached to the wheels for just such a momentum effect. I guess he was trying to capture the scale-weight affect. He must have been thinking about it too.

Paul Hillman

Tony Thompson wrote;

"As we saw a few days ago, the NMRA weights are not inconsistent with a loaded car."
*****************************************************************************
That's my whole point. For the purpose of getting good model operation, the NMRA did extensive research into determining their recommended weights. Out of shear coincidence ( ? ) their figures are consistent with loaded car-weights?

This merely proves the issue that, in order to make my cars run well, they are NOT 10 times scale-weight, but very close to prototype-weight for loaded cars. If the weight of a loaded car is what is needed to make trains run right, then fine and so be it!!, because, we do not actually load and unload our cars, except for flats, gons & hoppers, unless one has Lionel or other, magnetic cow-loaders, etc.

OK!!! So the final answer/statement to "scale-weights" can be, as I HAVE been asked before;

Question: "How much does a real car weigh? Aren't these models really light compared to the real thing?"

Answer: "No, they're actually very close to the scale-weight of a loaded railroad car. We figure these weights from the weight of a loaded-car even-though not all cars are actually loaded on a train. But, it gives us the best operation and is a compromise.
********************************************************************************

Then, Tom Jones III wrote:

"The concept of "Scale Weight" really is a dead end, in my opinion."
********************************************************************************
Response:

Well not to me!!

OK, I've heard enough about scale-weights. I got my answers. Thanks!!

Paul Hillman

Paul Hillman wrote:

Tony Thompson wrote;

"As we saw a few days ago, the NMRA weights are not inconsistent with a loaded car."
*****************************************************************************
That's my whole point. For the purpose of getting good model operation, the NMRA did extensive research into determining their recommended weights. Out of shear coincidence ( ? ) their figures are consistent with loaded car-weights?

This merely proves the issue that, in order to make my cars run well, they are NOT 10 times scale-weight, but very close to prototype-weight for loaded cars.

Paul,

What is the prototypical weight for a loaded car? Consider the following tons per carload for sundry commodities in 1956:

Wheat 54.52 tons per carload
Cotton in Bales 19.92 tons per carload
Oranges & Grapefruit 21.33 tons per carload
Lettuce 12.81 tons per carload
Potatoes Other Than Sweet 18.99 tons per carload
Cattle & Calves 10.87 tons per carload
Fresh Meat 12.51 tons per carload
Anthracite Coal 57.06 tons per carload
Bituminous Coal 59.96 tons per carload
Iron Ore 65.32 tons per carload
Lumber Shingles & Lath 43.95 tons per carload
Pulpwood 31.41 tons per carload
Gasoline 29.50 tons per carload
Fertilizers 45.61 tons per carload
Manufactured Iron & Steel 39.90 tons per carload
Iron & Steel Pipe & Fittings 37.11 tons per carload
Passenger Automobiles 7.28 tons per carload
Motor Vehicle Parts 17.43 tons per carload
Cement, Natural & Portland 54.61 tons per carload
Lime 42.79 tons per carload
Woodpulp 20.81 tons per carload
Newsprint 26.61 tons per carload
Refrigerators, Freezing Apparatus & Parts 10.19 tons per carload
Furniture 8.51 tons per carload
Liquors, Malt 29.60 tons per carload
Sugar 41.46 tons per carload
Food Products in Cans or Packages Not Frozen 26.18 tons per carload
Feed, Animal or Poultry 26.44 tons per carload
Scrap Iron & Steel 46.06 tons per carload
Car Forwarder Traffic 10.69 tons per carload

I can only conclude that the weight of a prototypical car when loaded varied considerably even among the averages - for boxcars, for instance, from 8.51 tons per carload for Furniture to 54.52 tons per carload for Wheat.

Tim Gilbert

Tim Gilbert wrote;

"What is the prototypical weight for a loaded car? Consider the following
tons per carload for sundry commodities in 1956" :

Wheat 54.52 tons per carload
Cotton in Bales 19.92 tons per carload
Oranges & Grapefruit 21.33 tons per carload
Lettuce 12.81 tons per carload
Potatoes Other Than Sweet 18.99 tons per carload

etc., etc.
*********************************************************************************
Tim,

My initial analysis was based solely upon MAXIMUM car gross weight. It doesn't matter what the load was. It could be lead or feathers.

The statement might better be worded as saying, " the NMRA weights are not inconsistent with the "MAXIMUM WEIGHT" of a loaded car."


Paul Hillman

NMRA guidelines notwithstanding, I have run cars of various
weights on several layouts and my experiences vary from car
to car. Some light cars run fine, some don't. Same for heavy
cars. The heavier the car, the more force on the "journal"
of the axle -- I have seen many plastic needlepoint axles
literally worn down to a nub because of excess car weight.
An HO sprung truck's sideframes will bow outwards under too
much weight, changing the position of the axle end in the
sideframe bearing and greatly increasing friction and wear.
None of this has anything to do with prototype axle loads.

Tim O'Connor

This is the same thing that the prototype has had to deal with. Now we're getting down to the "nitty-gritty" of the TRUE prototyping of our model railroad cars,..... theory of parts & materials in action. Total dynamics!

Weren't archbar trucks downgraded, and friction-journals, etc., for similar reasons, et al?

What causes prototype "hot-boxes"? They'd figure it out, then change the materials & methods!! These things were all caused by loadings, empty or loaded. The same as in our models.

Long Live Model-Railroading!!

Paul Hillman

Paul Hillman writes:

This is the same thing that the prototype has had to deal with. Now we're getting down to the "nitty-gritty" of the TRUE prototyping of our model railroad cars,..... theory of parts & materials in action. Total dynamics!

Ah, well. Mebbie so. However, if you really want to simulate total dynamics, flatten a metal wheel. Kind of interesting. The thing does clank along...somewhat prototypically.

Mike Brock

Paul:

My only question is: "Why scale WEIGHT?" What do you achieve by having exact
scale weight, vs. weight that makes the car act and appear to have the same
mass as the prototype would under the same circumstances? I am not
challenging you, I am simply trying to figure out what it is you wish to
achieve.

Tom Jones III

Mike,

That WOULD be an interesting little "detail" to put on a freight-car. I think I'll try that just for fun.

Once somebody suggested attaching some kind of device to a rail, to make it pull down as the wheels pass over, from the weight, just like we often see on the prototype. I'm gonna try that too, without having to add 20 lbs. of weight to the car.

Paul Hillman

Tom,

Actually to me the answer is quite simple, (but then I'm kinda weird some say), because of the general context's of the STMFC's stated purpose and the MANY topics discussed in this group. Everything possible seems to be considered for discussion, from the scale size of rivet-heads, to exact underframes, exact brake-wheels, exact metal-thickness, exact car-color & weathering, ad infinitum!! Scale-weight is just, in fact, another part of the total scale-picture!

But, James Eckman just posted a link to the page, "Railway Engineering", that very interestingly covers the scale-weight & car-weighting issue, by Steve Hatch, questions 9 & 10. As per Hatch's hypothesis, weight doesn't, almost, matter at all, and states why. His theories actually argue in favor of why NOT use actual scale-weight in our cars? Therefore, the case for actually attaining the scale-weight of a model, to me, should become an additional function in the total scale-building formula, as well as the question, "What color would be the under-carriage of a NYC freight-car traveling through Phoenix, Arizona in August of 1947."

Paul Hillman

And now I understand your desires. Thank you.

My focus was more on simulation of scale momentum of models, yours is the
faithful creation of models. Sadly, in my opinion, the twain don't meet
here.

Tom Jones

Tom Jones wrote:

My focus was more on simulation of scale momentum of models, yours is the
faithful creation of models.
****************************************************************************
Tom,

I have ALSO been interested in trying to do "flying switches" (correct-term?) with boxcars into sidings, etc., and have frequently tried it by fine-tuning the trucks and car-weights. But short of putting a fly-wheel in a car, like John Allen did, I didn't have all that much hoped for luck,.....yet.

Paul Hillman

Paul Hillman wrote:

Weren't archbar trucks downgraded, and friction-journals, etc., for similar reasons, et al?

You mean, of course, solid bearings . . . <g>.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@signaturepress.com
Publishers of books on railroad history

I think that may be the only solution, short of having a powered truck that
simulates the inertia/momentum of a car. It could be completely self
contained; one would need a way to sense rotation of the wheels and a simple
computer to calculate the resistance or accelleration, etc. But, I wonder if
it might not be quite expensive.

Of course, if you don't care too much about the appearance, I would think
you could add very heavy axle weights to the two inner axles on most freight
cars. They would resist rolling, simulating inertia, and would likewise
resist stopping, simulating momentum. I don't think lead would give enough
resistance - perhaps spent uranium? I don't know if the flywheel effect
would be enough to drive the car very far, but it would be easier than
driving a flywheel inside the car with belts or rubberbands.

Tom

I mean solid bearings? Do I? I guess! But, at the "Birmingham Rail & Locomotive Co." page, URL

http://www.bhamrail.com/parts.asp#locowheel<http://www.bhamrail.com/partsasp#locowheel>
They refer to:

****************************************************************************

ALCO

For 660-hp to 1,000-hp switchers with 7" x 14" friction bearing journals - Blunt style trucks

Also available: converted roller bearing.

For 660-hp to 1,000-hp switchers with 61/2" x 12" friction bearing journals - AAR style trucks

Also available: converted roller bearing.

****************************************************************************

I guess I left out the word "bearing", but I've always referred to them as friction bearings or friction journals. I guess it depends upon what part of the south one's from.

Paul Hillman

On Sunday, August 21, 2005, at 05:22 PM, Paul Hillman wrote:

I mean solid bearings? Do I? I guess! But, at the "Birmingham Rail & Locomotive Co." page, URL

http://www.bhamrail.com/parts.asp#locowheel<http://www.bhamrail.com/ partsasp#locowheel>
They refer to:

*********************************************************************** *****

ALCO

For 660-hp to 1,000-hp switchers with 7" x 14" friction bearing journals - Blunt style trucks

Also available: converted roller bearing.

For 660-hp to 1,000-hp switchers with 61/2" x 12" friction bearing journals - AAR style trucks

Also available: converted roller bearing.

*********************************************************************** *****

I guess I left out the word "bearing", but I've always referred to them as friction bearings or friction journals. I guess it depends upon what part of the south one's from.

Paul Hillman

You are right. "Friction Bearings". At least that is what the RR men working in the field and on the ground called them. I never heard them called solid bearings until I got on some of these lists. That is about 45 years after I left the RRs. I am not from the south. I worked for Un Pac and John Santa Fe in Kansas. Had a friend in KS from the RI and same terms used.
Thank you
Larry Jackman
ljack70117@adelphia.net
You can't have everything. Where would you put it?