Improvements for a Bachmann Spectrum 4-8-2 Mountain

[doctorwayne]

I have one of the early USRA Light Mountains, too, and had some issues with it early on. My maintenance records show that I fabricated a new connecting rod for the right-side valve gear (no date given), and in May of 2005, fabricated a new eccentric crank, also on the right side. At the same time, I found the drivers to be out-of-quarter, and after re-quartering them by-eye, applied ca to the engineer's (right) side drivers on axles 1 and 2, and to the Fireman's (left) side on axles 3 and 4.

I did have some issues with Bachmann's plug system, both with electrical continuity, and with the stiff wires often causing the front truck of the tender to derail. Since I run DC (and no headlights), in January of 2010, I removed the Bachmann circuit board from the tender and re-wired the loco so that it will run without its tender (useful for workbench operation using jumpers from a separate power source). I also installed new wiring between the loco and tender using mini-plugs.
The following month, I began re-wiring all Bachmann and Athearn steam locomotives in the same manner, and performance has generally been very reliable.

I re-detailed all of my locos to some degree, and I can't recall when the Mountain (it's a Mohawk on my layout) got modified, but in addition to the obvious changes, I replaced the air tanks under the walkways with lead-filled brass tubing. There's probably added weight internally, too, but it's been some time since it was done, and I can't recall for certain. The locomotive is a fairly smooth runner, if a bit noisy, and also a good puller.













If you feel that there's some binding, and can't find any interference in the side rods or valve gear, check the drivers for proper "quarter". The easiest way to do this is to run the loco and then stop it with the driver counterweights on one side all at the bottom. If they all line up in pretty-much the same position, then that side is okay. Next, without moving the locomotive, look at the drivers on the opposite side: they should have the counterweights all in the same vertical position, towards either the front or rear of the locomotive.
There's usually enough "slop" in the mechanism that one or two counterweights a little out of step with the others shouldn't cause a problem, but if any are grossly out-of-step, they'll need to be re-aligned, then have some ca applied to the interface between driver and axle. The ca won't bond to the engineering plastic, but it usually turns the axle-into-wheel joint into an interference fit. When wheels get too far out-of-quarter, the locomotive won't run, and it may also damage some of the valve gear linkages, as was the case with mine.

While I do have a NWSL "Quarterer", I usually have good luck quartering "by eye", although it often still requires that the wheelsets be removed from the locomotive. In that case, clean oil and grease from the areas where you'll need to apply ca, and make sure, once the glue has set, that the wheelsets go back into the frame with the wheels on the proper sides.


Wayne