ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Online since 2002, it's one of the oldest and largest model railroad forums on the web. Whether you're a master model railroader or just getting started, you'll find something of interest here.
Ok this might be one of those obvious questions but I need to ask it any way to make sure. If the weight of each car is done with the 1 oz plus 1/2 oz per inch formula to get the correct scale weight on say a 10 car train that could get a bit heavy. Now the weight could cause the engine to lose traction and spin the drive wheels. If I am thinking right. So how would you make sure your engines are the correct weight? Take the actual weight, by model of engine, and divide it by .87 or .087. And also would this help in the pulling of the correct weighted cars too. I am thinking the correct weight engines would help with traction and pulling the correct weight cars.
And also how would you add weight to the engines (Diesels). With the stick on weights like I am planning to use on the cars?
I'm speculating here, but I believe since locomotives are powered the weighting rules do not apply. It varies from manufacturer to manufacturer, but generally speaking the heavier the loco the better the pulling power.
And just like the real railroad, if you've got a long train add extra power!
So how would you make sure your engines are the correct weight? Take the actual weight, by model of engine, and divide it by .87 or .087. And also would this help in the pulling of the correct weighted cars too. I am thinking the correct weight engines would help with traction and pulling the correct weight cars.
The "correct" weight for cars has nothing to do with prototype and 1/87th scale. Since physics don't scale down, the NMRA formula is just a practice that has proved to be effective to keep the cars on the track. Likewise 1/87th weighted locomotive doesn't apply either (however if it did it would not be 1/87th since mass is, in simplistic terms, at least a 3 dimensional measure).
So the "correct" weight for a locomotive is the maximum amount of weight that can be put into it without exceeding the motor's current draw at full slip. With today's efficiency of the motors, I know of very few locos that have room for that much weight.
And also how would you add weight to the engines (Diesels). With the stick on weights like I am planning to use on the cars?
That is a harder question. Usually the manufacturers have already crammed as much weight in there as is possible. In the past I have filled the cab with led, removed any fiber optics for head lights and replaced that space with lead, and even put lead into tiny nooks and crannies in the trucks.
Sure stick on weights will work if there is room for them. The problem with some of those brands of stick on weights is the thickness of the foam adhesive. Any thickness of adhesive is space that could be used for more weight. It is amazing how an extra 1/4 oz can make a difference taking a train up a grade.
Actually, our model engine's weight scales down pretty close !
Take for example a proto-type RS3 that weighs 247,100 pounds. Divide that by 87 cubed and you get 0.375 pounds, or roughly 6 ounces .... not too far off what our model actually weighs.
I don't have any model tests to reference, but I'm pretty sure our model RS3 would probably be able to pull a similar number of cars as the real engine IF they were extremely free rolling. But that's where the cross-referencing accuracy falls flat. Our models don't have roller bearing trucks for virtually friction-free rolling and most of our grades and curves are unrealisticly steep and sharp which adds greatly to out pulling ability. A proto-type mainline curve translates down to well more than a 100-foot radius in HO scale !!! Our 24-inch radius curves would be like what you see in a proto-type industrial park .... maybe.
We just have too many things working against us. My general rule of thumb when making up a train (I run mostly all four axle power) is that one unit will pull 12 cars. If the train has more than 12 cars, it needs a second engine. I don't WANT a single engine to be ABLE to pull a 30 car train up my 2% grade.
I often wonder, to get a bit into the weeds on the left side of the creek, why the manufacturers don't offer 'heavyweight' versions of their locomotives in addition to the usual 'diecast frame' or diecast frame and body. A person willing to pay for the extra weight would pay for a tungsten steel version of the frame, even if it meant a premium of another $70 or more. The drives can handle the extra tractive effort amperage needed to move that considerably heavier frame, but oh....the traction! And no more traction tires!
I often wonder, to get a bit into the weeds on the left side of the creek, why the manufacturers don't offer 'heavyweight' versions of their locomotives in addition to the usual 'diecast frame' or diecast frame and body. A person willing to pay for the extra weight would pay for a tungsten steel version of the frame, even if it meant a premium of another $70 or more. The drives can handle the extra tractive effort amperage needed to move that considerably heavier frame, but oh....the traction! And no more traction tires!
As I'm sure you've witnessed many times over, the number of people who already complain about the high price of engines today .... I really don't think manufacturers would even consider that as an option ....
Mark R.'s analysis of the scaling factor for mass (weight on Earth) is correct. But as has been stated you can't redilly add weight to the diesel models. The friction created by our fairly unprototypical curves and grades (not to mention limitations of the amount of available room in most of our small layouts, dictates "selective compression" of the length of our trains. Some manufacturers add traction tires to their models. But, the other limitation, as was also stated, is if you overweight the locomotives you run the risk of overheating, or even burning out the motors and/or electronics. Far better to add another powered unit or even two to the consist, which is exactly what the prototype railroads do. I have a number of fairly hefty steam locomotives, which will pull quite a number of cars up my 3 percent grade. But rather than taking a chance of burning out the coreless motors (which are no longer made!), I'll double-head them up the hill.
