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E50 SN 25356 Date: 5/10/2016

Tech: user510

Receiving:

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Clean-up

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Plated parts; emi shield, case halves, retainers, etc are soaked in carburettor cleaner for 2 hours then rinsed in lacquer thinner.

The rotor is cleaned by hand using cotton balls and acetone.  The swivel bushing sleeves are rinsed in  lacquer thinner. (Further cleaning treatments of the sleeves are to follow after dimensional inspection.)  The oil retaining felts have been soaked in lacquer thinner.  Felts are still soft and will retain oil.  Will be soaked in acetone next to see if they clean up. Otherwise, replaced.

 

Inspection:

DSC_2575.jpg (354264 bytes) Checking stator coils for ohms:

Coil 1
Black - red: .85.1
Black - yellow: 55.7
Black - green: 266.2

 

Coil 2
Black - red: 83.8
Black - yellow: 54.8
Black - green: 264.7

These reads indicate healthy coils.  Why? Similarity of reads from coil 1 vs. coil 2.  Largest variation: 1.5 ohms at the black-green coils.  I'd worry if differences were greater than 5 ohms.

Dimensional inspection:

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Bushings sleeves. Gage is preset as follows: 0 = .1875

Bushing 1: .1871 all over, upper, lower and around.

Bushing 2: .1870 all over, upper, lower and around

Shaft:

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Observations: Obvious evidence of bushing run on shaft. Wear area is super shiny, everywhere else is less shiny.

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Using a 0-1 micrometer measures were taken within the wear zone and everywhere else.

Wear zone 1: .1867

Non wear zone: .1867  (no measurable difference.)

Bushing to shaft clearances: .0004 to .0005

Rotor shaft will be put in a small lathe and have its shafts pollished using Crokus cloth.  A very fine grit rubber abrasive.

Rotor shaft after pollish:

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Shaft diameter reads after pollish: .1866 - .1867.  All over. 

Rotor shaft with pulley after pollish:
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There were some heavily embeded foreign materials within the 60 hz pulley.  With the pulley mounted to the shaft, and the shaft in a small lathe, I used a green nylon scuff pad to clean and resurface both pulley surfaces.  The pulley is aluminum.

DSC_2589.jpg (332446 bytes) oil retaining felts after several rinse cycles in lacquer thinner (first) then acetone. 

DSC_2590.jpg (153708 bytes) motor bushings prior to the first oven bake.  (250F / 5 minutes)

DSC_2591.jpg (158581 bytes) motor bushings after first oven bake (250F / 5 minutes)

Acetone Rinse

DSC_2592.jpg (147640 bytes) motor bushings after 2nd bake (250F / 5 minutes)

DSC_2593.jpg (218579 bytes) Checking the bores via clean Q-tip.  This shot with a clean Q-tip inserted and pushed around abit.

DSC_2594.jpg (266649 bytes) Q-tip after withdrawal.  No apparent dirt.  Bushings and felts are ready to Oil.

DSC_2597.jpg (267157 bytes) 2 bushings soaking in oil. (Texaco R&O 46 (20 wt turbine oil)

Thrust bearing

DSC_2598.jpg (239167 bytes) The bearing ball is 2mm in diameter.  The oem thrust pad dimensions are: .25 x .035 thk.  Material is nylon.  The replacement thrust pad is .250 x .067 thick.  Material is Torlon 4301.  The oem (standard) part is an injection molding.  The replacement is lathe turned from a solid round rod.  The thicker dimension of the replacement part is intentional.

Reassembly

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The assembly procedure ,for all E50 motors, is documented elsewhere within the TD124 Dept. 

The end result with this motor, sn 25356, features a rotor that will 'finger spin' with ease.  When powered up runs smoothly with normal vibration levels and exhibits generous torque. It is now ready for many more years of service.