Screeching LokSound Atlas SD50

[conrad]

“You can put lipstick on a pig, but it’s still a pig.”

Sometime after installing a LokSound 73100 decoder into my 19 year old Atlas SD50 it began to screech.   Terrible bearing noise made for an unpleasant running experience.   I loathed to disassemble the loco because my previous experience with a noisy GP40-2 was a bear.  It is quiet at switching speeds but that is not the function of an SD50 especially since I have an SD60M and like to consist them.

However, trapped at home watching way too many YouTube videos solved the problem.  Several n scale maintenance videos show a lube job I had never tried.  As seen in the photo, a pin point worth of oil is placed in each bearing block.  Other than removing the decoder and a temp DC wiring job, no disassembly is required. 



It seems to work, but here’s a few questions:

How long should I test run the loco before reinstalling the decoder?

How long will the lube oil last?

And, am I just putting a band aid on an underlying problem?

Conrad

PS Word to the wise:   This loco did intermittently screech prior to my LoKSound install but I deluded myself into thinking “it’s really not a problem”.  By the time I finished I had forgotten the screech.  However, reality soon sank in.

[narrowminded]

You'll be good.  I lube those bearings almost anytime I have a loco apart and they're accessible , which isn't often.  It's easy so I do it but it probably doesn't need this but once over years. 

[peteski]

In that design the problem is usually the motor (not the worm bearings).  Worm bearings are plastic, so even with no lubrication there should be no screech.  Screech is usually in metal-to-metal bearings.

The motor bearings are made from sintered brass or bronze. They should absorb the oil, and not need any more for quite some time. Light oil is the best (gets absorbed the fastest).  Hmm, if other locos of similar vintage need frequent lubrication of the motor bearings I wonder if that batch of motors had plain brass bearings?

Funny thing is that when I saw the subject line mention LokSound and it was posted posted in the DCC forum, I thought that you had a problem with a screeching decoder, while in fact you had a mechanical problem totally unrelated to the type and brand of the decoder. 

[davefoxx]

Those bearings can squeal, and I refer you to the reason why Beardenizing works on some Atlas locomotives.  However, on the SD50, if I remember correctly, there is a universal joint in the driveline that prevents you from being able to Beardenize these longer engines.  A small drop of plastic compatible oil should last for a long time.

DFF

[tehachapifan]

Be very careful when adding oil to motor bearings. I typically put a very tiny drop on the end of a thin wire first to control the amount, then apply the drop to the bearing. I went straight from the bottle via needle tip once and completely took out a motor.

[conrad]

Thanks for the comments.

Peteski quote: "In that design the problem is usually the motor (not the worm bearings).  Worm bearings are plastic, so even with no lubrication there should be no screech.  Screech is usually in metal-to-metal bearings."

I agree, which is why I never lubed plastic bearing blocks in the past.  Interestingly, the screech when away after this lube job.  Only after a test run of some time did I lube the motor bearings.

Peteski quote: "Funny thing is that when I saw the subject line mention LokSound and it was posted posted in the DCC forum, I thought that you had a problem with a screeching decoder, while in fact you had a mechanical problem totally unrelated to the type and brand of the decoder."

Yes I got a little mixed up.  Focused on a tech topic that is not DCC/Electronics.  I'm so excited about LokSound I can't get it out of my mind.

Davefoxx quote: "Those bearings can squeal, and I refer you to the reason why Beardenizing works on some Atlas locomotives.  However, on the SD50, if I remember correctly, there is a universal joint in the driveline that prevents you from being able to Beardenize these longer engines."

You are correct.  There is a universal between the flywheel and the inner bearing block.  I did beardenize my GP40-2.

tehachapifan quote: "Be very careful when adding oil to motor bearings. I typically put a very tiny drop on the end of a thin wire first to control the amount, then apply the drop to the bearing. I went straight from the bottle via needle tip once and completely took out a motor."

Yes I am a big proponent of very tiny drops.  I did not dip the needle into the oil bottle.  I just placed a small drop from the applicator onto the needle thence to the bearing.

Thanks again

Conrad