scale wieght

Weight scales with volume, so you take the O scale ratio of 1:48, which is for length, and cube it.

48 x 48 x 48 = 110592

So, O scale cars would weigh about 1/110592 of an actual one, if in scale.

100 tons = 200,000 lbs, so the loaded car should be 1.8 lbs, which seems reasonable.

A model car that heavy may not work well in a train with unloaded cars, however.

Since weight is proportional to volume, you can divide prototype weight by 48 cubed to get model weight.  A 100 ton hopper if reduced to O-scale would weigh:

(100 x 2000) / (48 x 48 x 48) or 200,000 / 110,592 or 1.81 pounds or 28.9 ounces.

This is heavier than most O-scale freight cars and is about the weight of a diecast model of the car (like the Atlas O diecast hoppers and some K-Line diecast cars).

Your model locomotive will not pull anywhere close to the number of cars that the prototype can pull because the rolling friction of the car does not scale down.  Our models have much more friction relative to their weight than the prototype.

WyoRail has it correct for calculating "scale" weights, but as Bob and Charlie said there are other factors to consider.

Adhesion is hard to compare when models have rubber tires, but the prototype doesn't. Then, there is the rolling friction factor. Friction doesn't scale accurately considering all the factors involved (roller bearings vs. pin-point axles, non-scale flanges, too tight curves, etc. etc.)

Then, there is tracking ability based on the sheer mass of the prototype.

Jim

As Jim says, there are other factors at work.  But the 1.8 lb result (200000 lb divided by 48 cubed) is 29 ounces or a bit heavier than some 100 ton hoppers I have - but many models are in that ballpark. 

Your question raised an interesting question for me.  What about locos?  A UP Big boy weighed around one and a quarter million pounds.  So:

  1,250,000 lbs divided by 48 cubed ==> 11.3 lbs. 

I can recall off hand the weigh of my JLC Big Boy by I think it is a bit more than 12 pounds.  So it is heavier than scale.    Interesting . . .

Thanks so much for all of your input. I just thought it would be so cool to really deliver full coal loads of hard coal from a breaker to a distribution yard, where the coal would be loaded into tracter trailers. At the present time I can pull 30 fully loaded cars filled with (granulated to scale) Pennsylvania hard coal, with a single MTH diesel, which has two drive motors. I keep the axles well lubercated. I found that pulling more then 15 cars per drive motor over heats the motor. My layout is too small right now to add more cars and engines, but hope to someday pull 90 cars with 3 engines. How much more prototypical can you get? A hill where pushers would be needed would be such a rush, no drug could match it. That is why this hobby is so addicting. For me, the closer I can get to reallity, the more fun it becomes.

My MTH Greenbrier weighs in at about 13 pounds. I think the Lionel Big Boys are around 20.

At least, they weigh enough that somebody thought it'd be a good idea to caution owners to test their bridges before running these locomotives over them.

---PCJ

Can someone tell me what the formula would be to calculate O-gauge weight? What should a 100ton 4 bay hopper car weigh loaded, if you were to scale that weight down to O-gauge?

The O scale Standard is 5 oz plus 1 oz per car's length[excluding couplers for length measurement]!

What is really amazing, is that the coil springs, on the MTH trucks, will actually compress and rebound, when the wheels pass over a turnout or track gaps. Its as though the springs are perfect to the scale load placed upon them.

100 tons in O scale would still weigh 100 tons.

If you could take an automobile and crush it down to the size of a sugar cube, do you think it will weigh less because it's smaller?  The only thing that changed is the density of the object.  And would the weight of the plastic in a O scale boxcar weigh the same if it was expanded up to the size of a real one made of steel? 

Having said that, I agree with the NMRA being a factor of functionality and operability rather than "scaling with volume." 

Carefully documented tests, show a decided advantage in performance past obstructions in the track for cars weighted to an optimum weight. Since the radial forces tending to cause derailments are greater in longer cars, this optimum weight will vary with car length.

While cars of less than optimum weight will often perform satisfactorily on good track work, increasing weight to the optimum will improve the safety factor with which rougher track will be negotiated. Mixing light weight cars into a train of heavier cars is not recommended because of the possibility that the lighter weight cars may be pulled off the track in sharp curves.

Weight in excess of the optimum will seldom add to the ability of a car to roll down a given grade since the additional weight is almost exactly balanced by the increased friction of the axles in their journals. Extra weight simply adds to the drag of a train and adds more weight to be lifted to the summit of a grade.

Cars should be constructed to keep the lowest possible center of gravity. Supplementary weight added to bring the car to optimum weight should be kept as low as possible.

To find the optimum weight of a given car enter the Table below in the desired scale and find the "Initial Weight". Then find the "Additional Weight" and multiply this by the number of actual inches in the length of the particular car body. Add this weight to the "Initial Weight" for the total Optimum Weight of the car.

John, scaling down and crushing are two totally different things. A cubic foot of iron weighs roughly 450 lbs., an O gauge cubic foot of iron is 1/4 x 1/4 x 1/4 inch peice that would weigh no where near 450 lbs. on our model railroad but comes out to about .004lbs. in reality or.06 OZ.. My math maybe a little off, I'm trying to do it in my head, but the original premise is still true, scaling and compressing are not the same.

450lb/1728 cubic inches=.26lb 

there are 64 cubic O gauge feet in 1 cubic real inch

 .26lb/64=.004llb or .004x16oz. = .06 oz in reality

Jerry

I'm aware of that Jerry, the main point of my post is that you can't scale down physics, and a given weight of an object (i.e. 100 tons) will  be the same no matter what size the object is.

If you want to accurately calculate how much an object would weigh if you use less material to equal the dimensional sizes of o scale, you'd have to know the weight of every single component of that object, from the sheet metal right down to the rivets holding everything together.

I have some flat cars and gondolas that need between 6-8 ounces of weight added to them, they're either the old IDM cars or Lionel.

Most of my tank cars need between 4.5 and 6 ounces of weight, they're mainly MTH with one IDM and one Lionel in the mix.

My boxcars (MTH, Atlas, Lionel, Weaver) are pretty close, with only a couple needing weight added.  Most are over the recommended weight but they track wonderfully.

Die-cast trucks make a big difference on the Weaver cars and all their new ones come with them.

What truely amazed me after posting the original question, is that when I weighed the 4 bay hopper car, it's weight is 29 ozs. That tells me the formula is correct. But I believe its only because the coal size was scaled down, eliminating air gaps and the formula, scales down the cubic yard.

While you could figure out what a scale car would weigh if you stuck it in a miniaturization machine (ala Fantastic Voyage) I don't see how that weight would mean anything given that the rest of the physics is based on the actual mass of the objects and mass has no scale factor.  There aren't square pounds or cubic kilograms.  The actual weight distribution on the models is even more bizarre and the frictive forces are based on 1:1 surface properties and contact points.  I wouldn't be surprised to find that a real 1:1 rail car has about as much actual surface contact between its wheels with the track as do out toy wheels do on toy track  with our larger flanges and deeper treads.  

Weighing cars so they work correctly on the layout makes sense.  Worrying about "scaled" weight might be a nice intellectual puzzle but it doesn't mean much in the way the trains operate.

John

What if this crushed object was on the moon, how much would it weigh?

In a scence scaling down the planet it is located

Carefully documented tests, show a decided advantage in performance past obstructions in the track for cars weighted to an optimum weight. Since the radial forces tending to cause derailments are greater in longer cars, this optimum weight will vary with car length.

Agreed! That's Why I weigh all my freight cars to the NMRA Weight recommendations!

While cars of less than optimum weight will often perform satisfactorily on good track work, increasing weight to the optimum will improve the safety factor with which rougher track will be negotiated. Mixing light weight cars into a train of heavier cars is not recommended because of the possibility that the lighter weight cars may be pulled off the track in sharp curves.

YEp! so true! Once you weigh and bring your freight cars to the NMRA weight recommendations you will see a difference in performance! I sure did.

I do have exceptions though....

K-line Die cast Hoppers

Atlas O hoppers

MTH Premier Autoracks [overweight them to 30oz to minimize the top-heavyness. The cars come OEm NMRA weighted and are still top-heavy]

Sometimes you just have to go beyond the guidelines and experiment.  

Some time earlier this year, I posted a video of my "war train" consisting of numerous flatcars with two diecast tanks, etc., per car, making some of them very heavy and all of them together by far the heaviest train I have ever run.  I also had three very large scratchbuilt railroad cannons, the last 29 inches long and weighing nearly four pounds with 36 wheels and one 15 inches long and weighing not much at all.  The train was not quite the longest, but by far the heaviest, I ever ran. 

I found NMRA guidelines helped but not entirely.  Ultimately, I had to exerpiment with which cars worked best up front, etc..  Generally I put heavier cars earlier in the train, etc.  A few cars were very light and I had to weight them a lot.  A few light ones and merely put near the end of the train, just before the caboose.  Strangely my big railroad cannon, although as heavy as many locos, worked only near the end of the train.  Eventually I got the thing to run dependably and it was a lot of fun, but it took over a day of experimenting.

All my freight cars are brought up to NMRA standard which is plenty heavy enough.  You don't want them to be "scale" weight.

.....

Dennis

There seems to be a misconception of the definition of a “100 Ton” hopper.  The term 100 ton refers to the maximum load the hopper can hold.  This is the cars capacity, not its gross weight.  A 100 ton capacity car would typically have an empty weight of about 31.5 tons.  When loaded to capacity the total gross weight of the car would be 131.5 tons or 263,000 pounds.

To reduce the weight to O scale it would be 263,000/110592 = 2.378 pounds or about 38 ounces.

Here is an equipment diagram for a PRR class H43, “100 Ton” hopper.  It’s also interesting to note the specified minimum radius track that is allowed for this car.

Switch over to legacy engines and control and you'll be able to "load" the train without adding weight to anything. You'll even hear the diesel engine strain as is pulls the load while you crank up the throttle pulling against it. You won't burn up motors or shear teeth off of gears.

I don't think the laboring sound has anything to do with the goal of making cars heavier when it is necessary.  Even running in conventional, if you know how, you can get "labored chuff" on steamers and a deeper "loaded" sound from diesels.

My experience is that you sometimes have to do it with long or special trains to avoid stringlining.  With long, heavy model trains (e.g., enough cars on back there that the model cars you are pulling add up to a big weight), the cars up front in the train, even those to NMRA guidelines, can stringline on curves trying to pull all that weight.  I've had it happen - the first time when I knew nothing about 'stringlining" and had to look it up.  

Extra weight in "early" cars in the train (those nearer the loco) holds them down against stringlining.  I've had to do this with really long trains on my layout, and with heavy trains (my war train, as posted earlier in this thread).  I've always assumed, by the way, that this is why tenders, even plastic ones, tend to be weighted so they are quite heavy.  

No it doesn't Lee, and typically "making cars heavier" is used primarily for better tracking,this is more common place among two railers with the correct scale wheel flanges which are much more prone to derailment. I was referring to Daves first couple of posts where he was wanting a "prototypically" heavy train. Weighing each car down 2lbs seems like it could be hard on locos.. The "train brake" slider control on a legacy controller allows the operator to  create the "illusion" of a heavy train, the more it is increased, the heavier the train, the harder the locomotive(sounds) works, the more throttle is needed to increase or maintain the locomotive speed,too much train brake will even stall the loco.In the case of a steamer,one can set the load fairly high to the point where locomotive speed will not increase,even when the throttle is "pegged" creating an effect mimicing Rich Melvins trip up horseshoe curve with NKP 765, i.e loud,blasting, chuffs at a crawl. This is an entirely different effect than the automatic variable chuff your getting conventionally and can only be accessed under legacy.

Nothing against Dave or his idea, just a different way to achieve a similar effect. I'd love to see Dave post video in the future of a heavy multi-unit train. It would be neat to see the 1;48 truck springs compressed like the prototype.

You're right.  Loading up a train too much isn't a good idea at all.   

I know I could play with more sounds in Legacy, but I'm actually quite happy with the sounds I get in conventional.  I was running the little Lionel 0-4-0 shifter this morning (its conventional only) -- at about 9.5 volts (a smooth scale 25 mph which is a nice speed for it) -- it has a wonderfully deep and quite complicated chuff-shiff-shuff-chuff rhythmic staccato to it. Lionel has really done remarkably well with its sound cards recently.  Dollar for dollar it has to be my favorite (the Norther 3759 is my favorite - but it cost three times as much).

What are you using to weight your cars and how are you attaching the weight?

hello guys and gals.........

ok guys, so what will the weight be of the Santa Fe #5021 in "O" scale be ?  The real #5021 weight is 536,000 just the engine its self.  I wonder how much weight is a 1970 ford F100 truck and man or woman or maybe a 36 inch tv set or a 4 pound T-bone steak (Texas guys love that) would be in "O" scale HEE HEE ? 

the woman who loves the S.F.#5021

Tiffany

Jeff,

I hve used different materials for different cars.  In a box car you can use anything since it won't show if you close the doors.  I have some boxcars with wood blocks in them.  Gondolas with a steel load.  Tanks cars I open up and pour ballast stones in them.  In each case I have the car on the scale and bring it up to the NMRA standard for the length of car.

Incidentally, I got tired of doing the math so I made a chart in Excel that shows the weight required for each length car in 1/4" increments.  If anyone would like it, just email me and I will email it back to you.

.....

Dennis

How do you keep the ballast from shifting in the tank cars?  I have a bunch of those to do, but I'm thinking I'd like the weight to stay put.

what will the weight be of the Santa Fe #5021 in "O" scale be ?  The real #5021 weight is 536,000 just the engine its self.  I wonder how much weight is a 1970 ford F100 truck and man or woman or maybe a 36 inch tv set or a 4 pound T-bone steak (Texas guys love that) would be in "O" scale HEE HEE ?

Tiffany

The original reply has the correct formula for calculating the correct weight of an object in O scale.  It is 48 cubed.  That equals 110592.

For a Santa Fe 5001 class

536000 lbs / 110592 =  4.85 lbs

A die cast O scale model will weigh about twice the scale weight.  That is because the real thing has a cast steel frame that is designed to be as light as possible to provide the required strength under a relatively thin steel boiler shell filled with water.  Our models have thick diecast frames and boiler shells.  Zinc is far more dense than water so our models are too heavy.  That is OK for us since we aren't in danger of damaging our track and the weight helps our locomotives pull well.

For a pick up truck

6000 lbs / 110592 = 0.054 lbs or a little under one ounce. 

For a man

200 lbs /  110592 = 0.0018 lbs or just under 0.03 ounces.

Your giant  4 pound T-Bone would be less than one one-thousandth of an ounce.

If you want to accurately calculate how much an object would weigh if you use less material to equal the dimensional sizes of o scale, you'd have to know the weight of every single component of that object, from the sheet metal right down to the rivets holding everything together.

John

No, you do need to do that.  You can but it would be horribly time consuming and the result would be the same as taking the weight of the object and dividing by the cube of the scale.  For us that is 48x48x48 or 110,592.  A 1/48 scale object that is a perfect model in every dimension and uses the same material will use 1/110,592nd the volume of the material.  Since the density of the material does not change we can know the scale weight of the model without having to measure every part of the original.

What truely amazed me after posting the original question, is that when I weighed the 4 bay hopper car, it's weight is 29 ozs. That tells me the formula is correct.

Dave

Congratulations for doing some very prototypical operations.  I get to operate on the Northwest Trunk Lines.  The layout features 2.5% mountain grades and a working coal loader at a mine.  A power plant is under construction as an on-line coal customer.  Car weights and locomotive tonnage ratings are very important when making locomotive assignments for heavy trains on mountain grades.

The NMRA recommended weight for O scale of 5 ounces plus one ounce per inch of car length gives us 15 ounces for a 40 foot car.  That equals about 52 scale tons for a 40 foot box car.  Forty foot box cars like the AAR and PS-1 designs were nominal 50 ton cars, that is they could carry a minimum of 50 tons of freight plus the weight of the car itself.  So the NMRA recommendation gives us cars that closely approximate a box car loaded not quite to it's maximum weight capacity (which was common) or a mix of loaded and empty cars in a train (which was also common).  The Lionel PS-1 and Atlas Trainman 40 foot box cars weigh in right about the NMRA recommendation.  MTH 40 foot box cars wight in at 17 ounces and the Atlas Masterline AARs weight about 19 ounces.  I prefer the 17 ounce weight for good tracking without being too heavy. 

I have found that all these cars play well together in any position in the train on mountain grades with curves over O-72 in trains up to 20 cars.  That works out very well for the NWTL since the siding lengths were established to accommodate 10 car passenger trains that are equal in length to 20 car freights.  With 40 foot cars weighted to about the NMRA recommendation a 20 car train weights about 1000 tons.  In the real world a Mikado could handle about 1000 tons on a 2.2% grade and our MTH USRA Mike can handle that size train on the NWTL.  If a freight is heavy, especially with loaded coal cars it will get assigned a larger steam locomotive, a set of electrics or diesels or a helper.    

Your 30 loaded coal hoppers weigh just over 3000 scale tons.  That is a lot of work for a single unit even on level track.  Few real real railroads would put a single unit on a 3000 ton train. Keep in mind that while real diesels differ greatly our models do not.  Real GP9s, SD40-2s and SD70ACes have vastly different traction motors and tonnage ratings.  But our model diesels usually have the same motor powering each truck regardless of the prototype they represent.  I would recommend putting a second unit on that train even if one can pull it.

Thanks for starting a good thread!

hello Ted Hikel...........

That's is very interesting !!!!!!!!!!! for my truck to be less than a ounce in "O" scale but my truck is a 1/2 ton and scales at 3560 pounds with the 390 and C-6 trans so i am guessing it be like 1/2 of a ounce or so.  My sunset 3rd brass Santa Fe #5021 is about 11 to 12 pounds just the engine itself ( i think) which i am to pick up in Dec but will weight it.

the woman who loves the S.F.#5021

Tiffany

I've had good luck just weighing rolling stock to the NMRA standards.  I don't really worry if my locomotives are "scale" weight, I just want them to have sufficient heft to handle whatever I hook up behind them.

As far as the calculations, I find it pretty easy to measure the car at, say 12 inches, and add 5, no complex calculations for me.

I use anything heavy to weight them, I have used automotive self-stick wheel weights, but I'm running low on those.  Stacks of large washers work for boxcars, a stack over each truck is my usual configuration.

gunrunnerjohn,

On the tank cars, you can drip some matt medium in there if you like. It will set up just like on your track.  Tank cars usually have a small openings in the bottom near the trucks.  I tape those shut with metal tape.

.....

Dennis

Sometimes you have to take them apart to get to any openings in the bottom, but I guess that's what I'll have to do.

Harbor Freight sells lead strips with adhesive tape on the back side that are perferated in 5 oz. segments. They work great for adding weight to a car.They are made for balancing aluminum car wheels and are found in the automotive section of the store.

the stick on lead weights are convenient and easy to use because you just pop them on the bottom of the car - no disassembly. 

When I am putting weight inside a car or loco (i.e., I am taking it apart to do so, I use pennies.  They have a good weigh in quantity, they are small and easy to slip into nooks and crannies -- and I always seem to have more than I need.

Dave, are those 5 oz segments or .5 oz segments?

The lead weights that came with my scale (from MicroMark) are too small for O-gauge.  They are only 1/4 oz.  I can't use them because it takes too many to bring a car up to standard.

I would like some larger ones.

.....

Dennis

Harbor freight sells 1/4oz and 1/2oz weights, at least that's what my search turned up on their site.

Here's the 1/2oz ones: HF 1/2oz Wheel Weights

My mistake Dennis. Gun Runner has the right ones (.5 oz.). By the way, is anyone making an O-gauge car scale that you can actually weigh the car in "scale pounds" when it is pulled over the scale? I know there are pretend scales, but don't know of any actual.