I have two sets of Stewart FTs, first run, with the Buehler motors. They have the correct plug and play NCE decoder to preserve lighting functionality (such as it is). Recently, running them results in a slowing consist. The front unit's lights all respond properly, but the motor seems...weak? The second A-B pair is pushing it turns out.
Partial disassembly and inspection turned up nothing obviously wrong. A full reset of the decoder solved nothing. With the shell off, though, I could nudge the driveline and it would take right off. But then you couldn't stop and try to start again, either direction. You'd need another nudge. Driveline has no binding, turns freely, yet acts like it can't turn itself.
Tore down to extract the motor. It's the good stuff, Buehler. DC applied to its leads causes it to take right off, smoothly with great control. I haven't tried resinstalling, maybe in the morning. Anyone have any ideas? It will run and adjust speed on DCC just fine, it just won't start or allow reversing without reaching inside for a nudge.
Mike Lehman
Urbana, IL
Hi, Mike...
Been there... done that! I was always under the impression that the Buehler motor was the crème de la crème of small motors but out of my roster of maybe 2 dozen Stewart F units I had two motors go south.
I tried cleaning the armature, loosening the brush spring, tightening the brush spring, lightly sanding the brushes... all to no avail. The motor would purr (removed from the chassis) and all of a sudden it would spark, smoke, draw high current and slow down... then go right on back to purring for another few minutes then, seemingly for no reason, go back to sparking and sputtering. Drove me nuts because I can FIX ANYTHING but I finally gave up on these! I toasted a Digitrax decoder (or two) and THIS motor was not going back in the engine.
I recall a replacement motor was about $30 and for about $50 I found I could buy a new chassis on Ebay so I went that route.
Don't know if there was a bad batch, like the P2K PA1 hi-amp motors from way back, or if it was just a QC issue that went away but I never found a cure. I tore the motor down and everything inside looked fine. Commutator was pretty clean other than the carbon from the sparking, nothing was pinched or shorted.
Sorry I couldn't be of more help, Ed
Ed,
Thanks for the data point. Misery loves company
Fortunately, nothing like the melt-down you recalled -- yet. Decoder seems to be OK, picks up power, sends it to the motor. Motor seems OK. No noise, scorch marks, etc. Does seem to only run when its running towards the top end, although I can idle it down and run slowly once going. Just can't restart. Little torque.
Is it no torque at slow speed on DC as well? If it's ok on DC, adjust the kick start a bit and you can probably get better low end out of it. You can isolate bits and pieces and make sure there no binds elsewhere, like popping off the worms and seeing if the truck gears roll free. The wheels should roll and the gears turn when you tilt it, it shouldn't slide.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
gmpullmanThe motor would purr (removed from the chassis) and all of a sudden it would spark, smoke, draw high current and slow down... then go right on back to purring for another few minutes then, seemingly for no reason, go back to sparking and sputtering.
An open circuit/high resistance concern such as sticking brushes causes low or no current so the only thing left is a short circuit.
Sounds like a pole winding had an intermittent short. Classic symptoms.
Jim
Randy,
It seemed to take virtually no effort to stop the flywheels on DC. Had it kicking in CVs 116 and 117 (it's NCE inside) and that didn't seem to help.
Since it was in pieces, I checked things over carefully. Are the motor bearings on these supposed to be life-time lubed? They appeared to be OK, shaft spun freely, but a little freer once lubed. The symptoms of a gradual slowdown fit one of the motor bearings getting hot and gradually slowing down, plus recovery on cool off. I lubed the motor bearings and that seemed to make an immediate improvement.
mlehman I lubed the motor bearings and that seemed to make an immediate improvement.
Mike,
That should be one of the first things You should always check on a Electric Motor. Ever see the oil cups on the shafts of furnace motors, that the owners, never oiled, or bothered to read PM instructions, then crying about the cost of a new one.
Take Care!
Frank
Frank,
Ordinarily, I do. This was one of those "lifetime" lubed arrangements. I confirmed my memory by - of all things - reading the instructions. The other parts of the drivetrain do require periodic light oiling, but supposedly the motor bearings don't. All's I know is that it's better now.
Mike sounds like a dead pole on the motor. The running at speed fine but won't start is the clue. Only repair today is replacement. Years ago some people would strip down the motor and rewind the commutator. ---- Ken
Ken,
Could be, but I think it's running well at low volts now that the bearing that doesn't need oil got oiled. Getting ready to rebuild the truck that keeps falling apart right now so I can give it a long enough test run to confirm the problem is corrected.
OK, got the failing truck fixed for now, so could test run. Now it acts like it's fixed, runs well. By the time I got that accomplished I managed to break a drawbar and had a trashed truck. I guess it's been apart too many times and the retainer catch at the ends of several of the sideframe plugs broke. Fortunately, with the B unit being a dummy and Stewart being good enough to used powered truck parts for dummy trucks, I was able to "midnight supply" a good used sideframe to fix the powered A unit truck that needed help. I didn't need chewing gum, but I did use some baling wire....
There, I fixed it. This works until I get something better. The baling wire needs some paint, though...
Check you work to be sure you didn't short something, then reinstall. For the broken drawbar, I found a piece of tough plastic and cut and filed it to size.