Here’s a cheap and easy way to make any PM-1 or MU-2 powered loco run a lot better.
Buy a bunch of 1/4 x 1/2 x 1/8 NdFeB block magnets, magnetized through the thickness. I used N42, and I’m pretty sure the pole pieces are completely saturated without spending the extra on N50. I bought mine from KJ Magnetics (www.kjmagnetics.com).
Stack four magnets. Find the north pole with a compass or other method.
(I stuck a nail to one end and brought it near the original motor magnet until it was attracted or deflected slightly.)
Take out the rear motor screw, remove the old magnet (which will greatly weaken the alnico magnet) and slip in the new magnets. Reassemble. If the engine runs the wrong way, reverse the magnet.
Here’s how it looks:
You can see Project Bowser behind our heavy lifter there. I’m a little behind in my forum thread.
(That’s the Wattsburg Yard throat area, by the way.)
You can also see a 1/2" cube with a hole in it, being used on a Tyco Switcher chassis. I need to refine the technique a bit for that motor. The magnet fits, but I need to finagle something to hold the pole pieces together. I was hoping the hole would be just right to clear the rivet, but the magnetization direction was perpendicular to it.
Results:
No-load current on one motor dropped from .60A to .40A without any other work (and it could have used other work, too). Top speed didn’t seem to drop a whole lot, oddly enough, but low-end performance and minimum steady speed both improved. If I had better test facilities, I’d give a more complete report, but I don’t yet. For $2, though, you can’t lose.
Funny you should post this now. I just did that with a Mantua open frame last night and it worked great! Took the start up from .44amps down to .30amps and the no load full speed from .52 down to around .40. Feels stronger and smoother too. I’m going to reinstall the motor tonight. I’ll post again tonight about any performance improvements it has.
Now if I could figure a way to quit it down a little.[sigh]
RR: Thanks for the tip. I’ll probably end up using super glue, if I go with a glue, so there’s less of a gap in the flux path.
L:
INteresting. What size and shape of magnet did you use? Who’d you buy yours from? THis is the PM-1 (small angle-mount) you’re working on too, or the MG-81?
I tell ya, that “Bud” guy (I can’t remember his last name just now) certainly has some good ideas. His site is where I learned about Jameco can motors and now these magnets and that’s two solid wins.
I’m working on the noise problem, too. One thing that seemed to help was taking out the wheels and cleaning the bearings, axles, and gear with solvent (I used alcohol, mineral spirits probably would have worked better). I dislodged a lot of grease from the gear teeth with a small screwdriver. After all those years, the oil was mostly gone, leaving the hard, unlubricating soap base.
I used some neodyne disk magnets I got at Hobby Lobby.(had them laying around) About 1/4" dia. and 1/8" thick. This motor is riveted together so I just stuck the magnets to the outside of the frame as close to the armature as I could get. I could run the motor with the amp meter attached and add or subtract magnets or move them around and see the effects on the meter in real time. I reached a point where more magnets raised the amp draw and decreased performance. I found 3 worked good. Two on top and one on the bottom. If I get a chance tomorrow, I’ll post some pics.
I cleaned and lubed everything and re-assembled it tonight. It ran better. Low speed was a lot better. If I had to assign a # to it, I’d say it improved 10%-15%. Still not flywheel/can motor performance, but it IS an improvement.
Iiiintelesting. I noticed this braking effect, too. I stuck a 5-stack in an old Life Like trainset motor, noted a large improvement, then added another 5-stack beside it and stopped it from running. I think these open frame motors, with their large current capacity, can produce a very great armature magnetic field, but 10 of those magnets was greater and caused a braking force. You may have run into this too.
When you can scrape up the cash, do try the stacked-magnet method I used! $2 buys 4 magnets from K & J, enough for one motor; minimum UPS shipping is ~$6 and would cover a LOT of magnets. I’m not trying to plug K & J, but their shipping was very fast and I am quite pleased. It’s really worth trying!
Relevant data: Tyco 0-6-0 #99 went from barely dragging itself around and drawing probably an amp, to drawing .32A free, .52A slipping. I timed speed using a 100 sft stretch of the V&E, and came up with a top speed of 60 mph and a creep speed of UNDER 1 MPH! No BS! This was on a plain-Jane Railpower 1300 cheapie, no pulse power or back emf or anything. It’s not silky-silent; I think the
There’s one problem that I don’t think I can over come though. It runs great on flat track. It runs great going up a grade. But a transition from flat to grade or a curve on a grade REALLY draws the amps and drastically slows the train down for a few seconds. It then recovers and runs fine, but it’s annoying. I think it’s just the nature of the motor. Mine runs a lot better in reverse than forward too![banghead] I’ll still fiddle around with it a bit more.
$45 for a flywheel/can motor ain’t in the budget right now.(see-market is killing me thread.[:D])
What kind of Mantua is this, anyway? 0-4-0, 0-6-0, etc?
You know, the way you used the disk magnets really shows how strong these are. Try sticking a ceramic magnet to the pole pieces to boost the power. REPELLED! I’m pretty sure your motor is running entirely on the NdFeB disks, and the alnico is just short-circuiting them slightly.
You might not want to do it until you’re ready to replace it entirely (as the alnico weakens when its flux path is interrupted) but you might be able to cure the reverse-forward problem by disassembling the motor and adding some shims to keep the armature from sliding back and forth. This might help the grade problem. It’s possible that the armature is bucking back and forth when the loco is suddenly slowed. Or maybe you have some strange eddy-current braking stuff going on when the motor loads up, with those disk magnets stuck on.
You can make the shims from thin brass or clear package bubbles. Drill the hole in the shim stock, then trim the outline round outside the hole.
Also make sure the engine isn’t just plain binding on curves.
It’s a Mantua heavy Mikado. I already tried the shims. Didn’t really help. It’s got a big silver rivet holding the block magnet to the frame. I really don’t want to mess with drilling it out. It might fetch something on E Bay if I don’t destroy it. I think it’s the PM 1. It runs good enough if I keep it on flat track.
Drill away! Break those eggs and make that omelet. You can replace the rivet with a nut and bolt. I think it would fetch more on Ebay if it ran well, no? And if you do destroy the motor, you can always pick up a $10 Tyco Shifter and take out its motor. They’re common as dirt, still cheap on Ebay where nobody really wants them, and a good source of PM-1s.
(Checking Evilbay completed listings, Mantua Mikes tend to sell for just a smidge over $30, so it won’t be a huge risk.)
If you already removed the motor armature to add shims, you might as well take out that magnet. They’re magnetized with the armature in place, and you kill a lot of the magnetism if you interrupt that flux path. The replacement NdFeB magnets don’t have that problem.
P.S. - Had another idea. How much vertical play or rocking is in the center 2 driver sets? And the back one, if that’s the geared one?
