Re: Back to the Penn Line Atlantic 'Old Tevh.'

mark wrote:
Charles Davis wrote:
David Nebenzahl wrote:
On 4/11/2008 10:19 AM Charles Davis spake thus:

DO NOT REMOVE THE ARMATURE from between the pole pieces. Doing so will
break the magnetic path (magnet/ pole piece/ armature/ pole piece/ and
back to the other side of the magnet.)
I don't know where you get this from; you seem to be repeating an old
myth about permanent-magnet motors.
Since Model Railroaders are quite often working with 'Old Technology',
it (the myth) is pertinent.

Disassembling such a motor doesn't
change the magnet at all.
Right! But with the older Alnico magnets (which aren't up to present day
standards) the "Motor" will be affected.
<snip>
Ah, being the guy who started all this.... Yeah, I saw the forward-backward
play in the motor as soon as I got it to run, then put it on the frame.
I've taken it apart, and put two washers in. No, no magnet looses its
magnetism in this case - that's silly. Don't believe me? Ever had a Wham-o
Wheelo, the wire frame with a wheel with a magnet as an axle? They're been
around since the sixties, and if you leave the wheel off, it
doesn't "loose" its magnetism.

For that matter, ever heard of this thing that they invented for ships
called a "compass"? That's basically a bar magnet.

Anyway, I'm working to eliminate shorts - *geez* the tolerances on this
thing! I've already had to line the body around the motor with electrical
tape, and cut some plastic that comes with a new shirt, under the collar,
to put between the insulated wheels and the frame, and the motor, and the
trailing truck insulated wheel and the frame, and on the tender, *more*
electrical tape between the insulated wheels and the screws.....

Right now, the wheels move if I push it, though every so often, it starts to
go on its own. Oh, and the headlight won't go in, with the wires attached
to the springs that hold the brushes tensioned, even when I drank the power
all the way up (and yes, touching the wires to the track, it lights up, so
there's no short there), and I've found that the damn thing wants more
current than a 9v battery provides (different bulb, in my hands).

Ghu, if I'd known all this, I wouldn't have bought the damn thing off eBay,
but looked for discount retailers and bought a new kit.

mark, with hopes that pushing it back and forth will break
it in more
Mark,
Most model locomotives use the chassis to conduct current. You shouldn't have to insulate parts of the locomotive from the chassis. The usual arrangement has one wheel conduct electricity to it's axle and the other wheel has an insulating layer in it. When assembling you have to be very careful to get all the conducting wheels on the same side. If you put one wheelset in reversed you get a short circuit. Typically the drivers pick up current from one rail and conduct it to the chassis, and metal tender wheels pick up juice from the other rail and conduct it to a motor brush via a wire. On better models the pilot and trailing wheels also pickup juice and feed it to the chassis.
A nine volt battery lacks the omph to operate the motor, although it is strong enough to light the headlamp bulb. To make the engine run, you will need a 12 volt power pack.
I assume you have tested the motor by itself, (removed from the locomotive) and it turns freely under power? And, with the motor removed the engine rolls freely?
Given both of the above, the only other thing to check is the mesh of the worm gear to the spur gear. If too tight it binds and the locomotivewon't run. If too loose, the worm will skip over spur gear teeth under load, which will eventualy damage the gears, especially plastic gears. You adjust the gear mesh by shimming the motor. Shim under the front will give more clearance, a shim under the back tightens the gear mesh.
Good luck.

--
David J. Starr

Blog: www.newsnorthwoods.blogspot.com
.

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