I have several power units from various manufacturers, in this example I’ll use two GP38-2’s. One from Atlas and the other from Proto 2000. Both are DCC and run great. My problem is this, I can take my Atlas GP38-2 and pull 19 cars un assisted up my 1.9% grade, the Proto 2000 GP38-2 (using the exact same cars) can only pull 10 up this same grade. Now the Proto GP is considerably less in actual weight than the Atlas.(Atlas comes in at 560 grams, and Proto at 324.3 grams) I can add the weight to the Proto2000 and it will accomplish the same pull as the Atlas. My question would now be, since I know I have to add weight to this Power unit, how much should it actually weigh. I know there is a standard set for Cars by the NMRA but I can not find one for the Locomotives. Where can I find or does any body know what this weight should be?
Assuming the locos are broken in and in good running shape, adding weight is probably the best thing you can do to increase its pulling power. On steam locos adding a traction wheel is also an option. Anyway, adding weight has some restrictions.
The first is actually finding room in the loco shell to add weight. I like the square weights with the adhesive attached to them that are typically used for weighting cars.
The second consideration concerns adding too much weight which will stall the motor and burn it up. You can usually figure out when “its too much added weight” by using an amp meter. However, I doubt you will find enough room to add weight that will cause you to worry about this.
For what its worth…
Mobilman44
How old is the Proto? If it is newer, it takes a while for the wheels to break in. I have a PK 2000 SD7, it is a 12 wheel all drive engine. When I first ran it, it would only pull around 12 cars up my grade, about the same as yours. After some run time it will now pull 21 cars up the same grade.
If it is older and broken in, add some weights. As long as it can spin it wheels when you hold it back, you should not hurt the motor and if DCC the decoder. If it cannot spin the wheels, you added to much weight.
Cuda Ken
Well if I had to guess, I would say that both units are about a year or so old and probably pretty well broken in at this stage. So I guess I will see how much weight I can add and have room for. So I am guess that there is no standard or minimum range? Guess I’ll have to see where the weight limit is in regards to traction and Amp draw and shoot for the happy medium.
If the loco has no craption tires then you can add as much weight that can be fit into it…I do this with all my locos…tires = no wheel spin and burned up motors and dcc decoders…extra weight and no tires = more pull but allows for wheel slip.
There is no weight standard for locomotives. The only suggestion I have heard consistently for the last half-century is, “The motor has to be able to spin the drivers if the train stalls.”
I have one small tank locomotive which is, literally, a block of lead with a wheel at each corner. The lead is only hollowed out enough to clear the large-ish vertical shaft motor - which can still spin the wheels…
While I haven’t used it, I understand that Bullfrog Snot will create a traction-tire-like coating on a plain metal wheel. That (or a real traction tire) will gum up the equation - if the train stalls, the wheels WON’T spin - and shortly the magic smoke will come wafting out…
Chuck (Modeling Central Japan in September, 1964)
Pulling power of locomotives (all scales including 1:1) is directly proportional to weight on dirvers. Double the weight, you double the pulling power. So you can add weight to HO locomotives until you run out of room inside the locomotive to hold it. More weight means more pulling power.
One small caveat. After weighting, the motor ought to be able to spin the wheels. If the motor stalls (stops turning) it will get very hot and even melt should the train get stuck somehow and the juice stays on. This is not usually a problem. There isn’t enough room inside HO locomotives to pack in enough lead to stall the wheels. But I always check, just in case.
The weighting standard for cars has to do with keeping them on the track. You want all the cars to weigh about the same, otherwise light cars get pulled off the rails by the heavier cars. It doesn’t apply to locomotives. For locomotives more weight is better.