Motor Friction and OILING THE COMMUTATOR!!

 I was sure I was going to cause a good bit of discussion when I made the first post.  However, I checked the old Hudson (2046) again tonight, and it definitely has very low friction.  It is pulling a tender + 7 cars, most of which are post war with a fair amount of friction.  It will run reliably with the track voltage as low as 9.5 volts.  This is measured near the engine, not by reading the transformer dial. 

 Brush friction is always a problem with a DC or universal motor.  It is usually the largest component of friction in the system.  I speak from long experience using DC brush motors for stabilized gimbals and other precision servos.  It may be that the oil becomes a problem as it ages, but I don't think it will.  The 2046 had been disassembled and the commutator and brushes cleaned before I started this experiment.  I used WD-40 and a soft wire wheel in a Dremel tool to clean both the commutator and the brushes.  The brushes are most likely the original brushes installed by Lionel.  The 2036 was not disassembled and cleaned.  The brush springs in both motors are the ones Lionel installed. 

The oil I used is AutoZone 5W-20 engine oil.  It is what I use to lubricate everything.  So called light machine oils like 3 in 1 are not good as they have a high vapor pressure and get gummy very quickly.  The engine oil has a very low vapor pressure as otherwise it would evaporate from the engine crankcase.  There are better oils to use that have a lower vapor pressure, but they are not readily available.  

I would recommend against using sand paper on the commutator.  The wire brush or other methods suggest in this thread should work better.  

I am not sure why the oil doesn't cause a problem with continuity through the brushes and commutator, but it doesn't.  I am going to continue to use the old Hudson over the next several weeks to see if any problems develop.  I may also oil the commutators on some other engines.

The way to test the effectiveness of the oil is to run the engine by itself and measure the track voltage when the engine is moving very slowly.  This way, the back EMF of the motor is small and the current can be calculated by dividing the track voltage by the DC resistance of the motor.  Conversely, a resistor of .5 to 2 ohms can be put in series with the transformer, and the voltage measured across the resistor and the current calculated.  Do the test on straight track.

Bruce

Bruce