[GreenKeys] Sync motor problems, again, Refurbishing techniques...

[pacquerat at comcast.net]

The start cutout switch has dirty contacts. 

Mark the locations of the motor end bells in relation to the stator and pull apart the motor, be careful of any spacer shims on the shaft. The start switch has a pair of blades that "feels" for the centrifugal disc, the disk may interfere with complete disassembly but careful maneuvering of the rotor will free the end bell. Clean out everything with Stoddard solvent (odorless mineral spirits), good time to wash out the bearings and the end bells. Locate the contacts of the start switch and burnish them. If there is no "meat" left on the contacts access to a brazing torch and an old relay to salvage for the silver contacts are in order. Inspect the centrifugal mechanism for any defects and repair as best as possible. If all is well with the contacts, force the Teletype lube of the day into the ball bearings and smear some into the bearing pocket. BTW: the bearings should have the bearing shield face the inside of the motor to prevent grease from accumulating. Assemble the motor and leave the through bolts somewhat loose. Keep a rubber hammer handy, power the motor. The start contact permits energy to flow through the starter windings giving a thrust in the correct direction and initial spin up to the extent that the centrifugal switch will actuate and disconnect the starter windings. The switch MUST actuate in a timely manner as the stater windings are very small gauge wire and will burn out if left "ON". Once the motor is up to speed, use the rubber hammer to seat the end bells. The motor will sound somewhat smoother running once smacked into alignment. Then tighten the end bells. Going forward, do not over lube the motor, generally, excess lube gets thrown onto the start switch and causes the contacts to burn until they are insulated... 

If the shims got messed up, assemble the motor without any shims so long as the start switch will actuate. Start the motor and note where the rotor aligns with the stator. Stop the motor and add shims accordingly to satisfy the location of the rotor as well as proper operation of the start switch, allow few thousandths end shake. That's it, Teletype sync motor re-furbed... 

The governor motor is a little different :) Needs additional attention to brushes, commutator, bearings & shims, clean-out all the old grease too. Never run the governor motor without the governor in series. The series connections of the field and armature will cause the motor to spin so fast there is danger that the armature windings or commutator segments could be thrown off and destroy the motor... 

YMMV 

Chas 

WA1JFD 


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