Hello. This is for ho scale, I know how to figure weight for rolling stock, but what about weght for steam loco’s? In particular a Bachman spectum 2-8-0, and an IHC 0-6-0 & 2-6-0. Is there a standard an engine should weigh? Thank’s
Larry
Steam engines can be tough beasts to increase tractive effort without adding tires like Rivarossi used to and BLI includes with their engines. Obviously weight plays a major role but equally important is that it be distributed so that all the weight is on all of the drivers. Packing one end with weight is worse than doing nothing at all. The weight has to be distributed so the effect is on all the drivers. Otherwise it reduces tractive effort. Let’s face it though. You won’t be able to replicate what the prototype could do no matter what you try unless of course you run yours downhill all the time. :-)!
Larry,
There is no NMRA ‘standard’ for engine weight. Most plastic steamers are pretty light, but the manufacturers are getting better at adding internal weight or use ‘traction tires’ to increase the pulling power of their models. Some of the old MDC steamers like the ‘old time 2-8-0’ had a cast metal ‘core’ with a highly detailed plastic exterior.
I have a pair of the Spectrum 2-8-0’s and they will handle about 8 cars up my 2.75% ‘hill’. The freight cars are NMRA weighted freight cars with free rolling metal wheel sets. I am quite satisfied with their performance. I had an old Mantua/Tyco ‘General 4-4-0’ that could not pull itself up that same grade. A Bowser/Cary boiler kit improved it quite a bit, but it may only pull about 2-3 cars up that grade(and this is an all metal engine)! Weight on drivers is the key here, and steamers are at a disadvantage due to the lack of places to add weight.
Jim
This is one dimension that is NOT prototypical. Can you imagine 750,000 lbs / 87 = 8621 lbs in HO guage ?? LOL WOW. I am not aware of any NMRA standard. I have used lead weights in the past, works pretty well, but I was concerned about the added strain on the motor. Current draw does increase.
Dick, you brought up an old discussion about scaling down weight. On model dimensions, you reduce the lenght, width, AND height by the scale factor. The final concensus was that weight was volumetric, so the scale factor would have to be cubed to find the figure to divide the prototype weight by to get the model weight. In HO scale, that would be 660776 (87.1 x 87.1 x 87.1) yielding 1.35 pounds for the prototype’s 750,000 pounds.
Personally, I prefer the metal boilered steam loco models. Many of these come close, or even exceed the above example.
Thank’s for the reply’s. I was not sure if there was a standard. I have no pulling problem’s, I was just curious to see if it would matter about making better electrical contact to the rail’s. I was not worried about making them prototpypical. I do not know how to count rivet’s LOL. Thank’s again.
Larry
BALANCED is the key. A properly balanced 1-pound 2-6-0 will more than likely outpull a 2-pound 2-6-0 that has all the weight in the smokebox.
–Randy
better contact on the rails means wheels being able to slide up and down with track irregularities.
many many model engines have rigid wheelbases which means if a rail happens to dip or undulate, it can force wheels off the rail reducing electrical pickup.
Mostly you find equalized or sprung drivers on brass lokies and they will track excellently.
Check for power pickup on non powered axles and if not see if you can retro some pickups on them.
No real standard on weighting engines, my plastic berkshire I poked weights wherever I could cheat them in.
TOM: Good info, I didn’t know that on the weight factor. So the formula would be Loco weight divided by 87.1 cubed, I’l have to log that down.
As much as a motor can stand and still slip wheels.
I simply buy more steam and double head em. BLI does well enough without installing the traction wheels. My 2-8-2 BLI Heavy mike can manage 15 cars up a 3% and start them if stopped.
In the protoype I think 1.6% or so is max for 15 cars depending on situation.