@Ted S posted:
Wow John. Of course if the loco didn't have four (4) rubber tires the wheels would spin a little when it was overloaded, so you would never see that kind of current draw in real life. For years, a cardinal rule of locomotive building and re-powering is that you don't weight a loco so heavily that the wheels can't spin when it's overloaded. Add rubber tires, especially four of them, and who knows! With gearing that low, the wheels might spin even with the tires. But the current draw will be higher than it would with just two, or no tires at all.
Ted that 42:1 gear box will peal a rubber tire off, like you peal a potato, if it is not glued on. The motor is never really loaded up on any of these 42:1 Williams locos they could get along with a 385 motor just fine. I think the ultimate upgrade would be a Maxon coreless the size of a 385. Pat I don't run trains very fast and I could live with 25mph on a freight loco especially on a switcher but a passenger loco should at least be able to run quietly at 50mph. Pittman does make some motors which will twist fast enough to do that. The closed case will keep the whine inside but the one thing that concerns me is the duty cycle with no vents to let the heat out. Your going to need 14,000 rpm to get to 50mph with 1.5" drivers and 42:1. The only way I know to deal with the heat in a closed case is a coreless motor but your not supposed to twist them that fast not because of heat or current draw their problem is the cup shaped armatures at high RPM set up standing waves and it deforms possibly causing the armature to rub on the field. Knowing this I have tested one, running it without a load, for almost an hour at 20K so far no problems. I have a mabuchi 545 in my J chassis right now but think I will stick a Maxon in it and give it a test drive. I need to work out the linkage to the gearbox. j