Is This Too Much Lube?

[bbunge]

Over the course of a year, my son and I put many hours on a BLI Mikado.  Great runner, ground sound, good puller.  Had to reset the decoder a couple of times, but that was about it. 

About a month ago, I was working on track, he running a train.  The Mike was sitting in the yard, not active since it had been released.  Track power was on.  There was a short beep as there was a short that cleared a second later.  I figured John's train shorted on a switch.  A minute later, it started and didn't stop.  I looked up, he was looking at me.  The track I was working was not powered.  He pulled the locomotive he was running off the track.  It continued.  He pulled the only over loco on the track off - the Mike, and it stopped.  I set the Mike aside for another day.

Some fooling around showed, yes, the Mike was shorting.  Nothing was really apparent.  Pulling the plastic base off didn't show anything apparent, but there was more lube in there then I expected.  I set it aside for later.

A month later, I start to check it more carefully.  The meter doesn't scream with the tender wheel.  It doesn't scream with the front and rear drivers if I wiggle them a bit.  I lift the drivers out of the frame.  With some more wiggling, only the third driver appears to be shorted.  It's really oily.  I wipe it as best I can, then carefully hit it a couple of times with CRC spray.  A day later, it still shorts.  There is still a lot of oil, so I wipe it as best I can again and hit it again with spray.  After drying, it doesn't short anymore. 

I've cleaned as much of the lube up as I can.  I have to wonder if we had run it hot enough at a recent show that lube up by the worm had run down and enough had collected to short across the split axle.  It certainly was interesting it just started... as we were standing there.  I'm currently storing it in the box, on the side since I don't want to tear into it to clean it all out.

Bob

[peteski]

Bob,  There seem to be few odd things about this.  You mention that the short is across the loco's left and right side of the track pickups. First, all the drivers are electrically interconnected through the chassis. You can't just measure short across a singe driver -- they all should show a short (if there is a short).  Since the tender track pickups are also connected electrically to the loco, the short should show up there too. Unless you removed all the drivers from the loco and tested each one individually.

Next, the grease/oil itself (regardless of how much of it is "glopped" inside the mechanism) is non-conductive. The only way  a short could occur is if enough metal shavings got into the grease to actually create a solid electrical path creating a short.  Was the short ever solid, or was it always intermittent?

When you eventually get to tear down  the loco, it will be interesting to find out where the short was.

[bbunge]

Peteski,

I had lifted the drivers off the chassis, holding them up with toothpicks, but they were still connected to each other via the rods.  When I measured across the wheels, by slightly wiggling them I could make the short become intermittent with drivers 1,2 and 4 in those moments where a rod wasn't touching the wheel cranks.  Only 3 was solid.  I didn't want to pull the rods off unless I had to to avoid the complexity of reassembly and getting the quartering correct.  I am assuming the axle is split under the plastic tube that also has the drive gear on it.  I wondered if perhaps the axle ends were in contact, but the wheel was in gauge.  So if not the heavy lube, I'm at a loss as to what is happening.  I suppose if it happens again, I'll need to remove the drivers from the rods and see if I can pull number three apart.  Ideas and advice always welcome!

Bob

[peteski]

Looks like I missed your mention that when you were checking continuity the drivers were no longer in contact with the chassis.  Since siderods only connect wheels on the same side, any electrical continuity between them and the metal part of the wheels should not play any role in a short between the left and right side wheels.

If the wheelsets in this loco are similar construction to the BLI T1 I have then there might be a sliver of metal shoring the axle (on the left) to the cup on the end of the right axle.  The metal wheels are electrically connected to the respective axle halves. They are insulated by a plastic tube in the center of the assembly. Cleaning all the grease out of that wheelset will hopefully reveal the problem.


Here is the wheelset assembly partially pulled apart to show all the components.

[bbunge]

Peteski,

Thanks for the reference photos.  Here is a shot of the unit before I lifted the drivers (#2 isn't connected to the rods, so I had already removed it).  Looks like the construction is pretty similar.  I'm now wondering if there was a shaving or something that I blasted lose with the CRC.   Hopefully that's it and my problem is gone.

Bob

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[peteski]

It is possible that some metal shaving got stuck in the grease, connecting the axle with the metal cup on the ther axle.  That would be a good example of too much lube causing problems.

[mmagliaro]

Can you blow up that photo of the underside, really big and close?

I'm wondering if some bit of metal got between the frame halves.  It looks like there may be some particles down in the gap between the
frames, but the photo isn't close enough to be sure.

[peteski]

Can you blow up that photo of the underside, really big and close?

I'm wondering if some bit of metal got between the frame halves.  It looks like there may be some particles down in the gap between the
frames, but the photo isn't close enough to be sure.

That is also a possibility, but Bob confirmed that the short was in the wheelset removed from the chassis.

[mmagliaro]

That is also a possibility, but Bob confirmed that the short was in the wheelset removed from the chassis.

Oh yeah... duh.  Now that I reread his initial tests, he narrowed it down to driver set 3 on its own, so nope,
not the frames.