Overland Brass Little Joe Question

[spookshow]

I just purchased one of these and it runs loud enough to wake the dead. Are they all like this or did I just get lucky?

Thanks!
-Mark

[wcfn100]

My dad's is a grinder too.

Jason

[victor miranda]

ah I didn't toss it on my watch list.

I thought brass locos tended to noisy...

is it an even and steady growl?

victor
 

[spookshow]

Well, it's even and steady, but I don't think "growl" really conveys just how loud it is. "Coffee Grinder" is closer. Definitely the loudest OMI model I've ever encountered.

Cheers,
-Mark

[u18b]

That is remarkable since other later OMI stuff is pretty good.

For example, I have-
SD45-2
AC6000
GP60

They are all designed the same and all run great.

I'm surprised.

[spookshow]

Well, the mech is pretty radically different from any of their previous models (two motors, etc). Actually, it kinda reminds me of that bi-polar you've been working on 

One problem I've found is that one of the flywheels isn't really attached to the driveshaft very well (half the time, the driveshaft spins and the flywheel doesn't). Gonna see if fixing that improves things any.

Cheers,
-Mark

[wcfn100]

I haven't even looked at this model since about a week after it came out, but didn't it have brass gears?


Jason

[spookshow]

It's a mix - the axle gears are brass and the intermediate gears are plastic.

Cheers,
-Mark

[spookshow]

Hoo boy, this is really getting crazy now... after fixing the loose flywheel with a little CA, I can now get it to run very smoothly and very quietly - but only under a very specific set of circumstances....

As I apply throttle, it will start out in typical coffee grinder / angry hornet mode. However, if I keep applying more throttle (up to basically the top), everything will suddenly align (or whatever), all the noise goes away, and it shoots forward like a rocket. At this point I can back off the throttle a little bit, but if I slow it down too much it will go back into coffee grinder mode.

Oddly enough, I can only achieve this "quiet mode" state in one specific direction. Going the other way, it never smooths out (no matter how much throttle I give it).

Any suggestions from the rocket scientist brigade? This is way above my pay grade 

Thanks,
-Mark

[u18b]

Hi Mark,

Ever since you bought this, I have been eagerly awaiting you updating the encyclopeadia.

Can we have any shots?  It's a bit hard to comment without knowing what we are looking at.

Of course you know in general, that high throttle at first then smooths out is usually a sign of high friction.

If I had it in my hands, I'd probably be looking at polishing all the metal gears on their "bearing" flat sides.  My work with Kumata gears shows how rough that mating spot can be.


Here is a stock rough gear, and here is a polished one.



Another possibility is that a flywheel is out of balance or not placed properly (you did say one was loose).

Think of your car tires.
Vibration is a funny thing.
At some speeds the vibration is horrible, but then at others it smooths out.
That's because of some kind of harmonic effect in the vibration.
Maybe you have something like that here.

[u18b]

Oh.....

And if you have been following my EP-2 thread, you know that I really HATE the two motor solution in N scale.

The motors MUST run at exactly the same speed, or they will work against each other (and noise and loss of traction potential will be the end result).

The EP-2 requires two motors since it is really two locomotives drawbarred together.

But there is no reason at all to place two motors in things like a Centipede, a DD40AX or a Little Joe.
When will manufacturers see that they are ASKING for trouble when doing this?

[spookshow]

Please excuse the crappy solders - that was me putting things back together ( ) and not Ajin.





Hey Ron, if you want to take a look at it, I'll be more than happy to send it to you 

Cheers,
-Mark

[victor miranda]

Hi Spookshow,

oil the motor bearings.
and if that does not work, oil the motor bearings.
then oil the worm bearings.

the noise is from the shaft bouncing around.
the motor is the most common place.
the bouncing uses a lot of power and destroys bearings from the hammering.

victor

[spookshow]

Victor, one of the first things I tried was to oil the worm bearings and the gears. Haven't tried oiling the motor bearings yet, though. Will give that a try.

Thanks,
-Mark

[u18b]

Mark.

I sent you an email.