Any reason my 2-8-0 should be running warmer than my K4s? Would different gearing account for this? Thanks- Mike
How much warmer? Is the motor too hot to touch, or just slightly warmer? Overheating can be caused by many problems: binding in any part of the mechanism (i.e. valve gear, side rods, worm and axle gear too tightly meshed, drivers out of quarter), a weak motor magnet, too much oil on the brushes & commutator, a shorted motor winding, etc. Have you removed the motor to check that the loco is free rolling?
I don’t know if there’s any difference in the gearing of the two engines, but all things being equal I’d expect the K4 to run a bit warmer under load because of its larger drivers.
The most likely cause would be a tighter mechanism. Does the 2-8-0 draw higher current than the 4-6-2? If it does, take the motor out a look for any bind. I remember when I was building my T-1 4-4-4-4, one of the siderods was a little too tight around its screw, and the the screw got hot and nearly welded itself to the siderod. I expanded the hole for it, and everything was much better.
If everything is fine and it’s still getting warmer, it could be that the H-9 has a design that traps more heat than the K4.
Warmer than warm to the touch and not blistering by any means. Just suprised that it was warm at all, I guess, which upon reflection seems kinda stupid. Bowser site lists gear ratio of K4 at 32:1 and H9 at 29:1 Mechanism rolls freely, but the whole thing is due for a tune-up. I wanted to see if these things run hot so I know what to expect when I’m finished with the tune-up, or whether I should replace it with a decapod, atlantic, or mikado. thx- Mike