In this article I will show how I clean and oil a small synchronous motor that is used in a figurine clock, Figure A. The clock is manufactured by the United Clock Company of Brooklyn, New York. The clock actually uses two nearly identical movements, one for the time mechanism and one to run the dancing ballerina and the accompanying music-box mechanism. The clock indicates that the motors are licensed under Westinghouse Electric Corporation, Patent 2140365.
A Google search shows the actual patent and diagrams. The motors used in the clock have evolved from the patent, but the patent provides interesting reading on what was patented. One such improvement was “to provide a new form of bearing element . . . involving such features as an annular enlarged lubricant storage head, absorbent means in said enlarged lubricant storage head whereby substantially all of the stored lubricant is held by said absorbent means. . . .” The movements in the clock are dramatically simplified from the ones illustrated in the patent. However, the inventor, B.E. Lenehan, provides information that will be helpful later when oiling the motor.
I will show servicing the clock motor, since it has the most opportunity for wear to be corrected since it runs continuously. The figurine, music box, and illuminating lamp are switched and don’t run continuously. The clock unit is removed from the case by removing the two retainer nuts and back plate, Figure B. The motor is removed from the clock body, Figure C. I next measured the distance from the end of the spiral gear to the cap end for future reassembly, Figure D.
The rotor arbor is next removed from the rotor cup, Figure E. The spiral gear is placed in an opening in the bench block, and the arbor is tapped out with a small round 1/16″ flat-faced punch. A washer is placed between the motor body and bench block for support. The disassembled parts are shown, Figure F. Next, the annular lubricant storage head is simply popped off the front bearing (note the opening orientation first), Figure G. The distance between the faces of the front and back bearings is then measured, Figure H.
The next step is to remove the front bearing. This one is most apt to have wear, and can be serviced while it is out. The rear bearing rarely wears, but will be removed, checked, and cleaned. To remove the front bearing, a piece of steel wire is cut about 2″ long, and the burr removed from the cut. The diameter of the wire is such that it can be inserted through the back bearing, tilted, and placed on the back of a milled or pressed recess ledge in the bearing, Figure I. The wire is lightly tapped once with a small hammer, and then tilted the opposite way and tapped again. Just two taps removes the bearing, which is not a tight fit at all. A tube also comes out of the cavity that sits in the milled or cupped recess in the back of each bearing, connecting them, Figure J. This tube is described in the patent as a journal for oil transfer to the back bearing, since there is no annular oil storage head on the back bearing. It also provides oil storage where the journal fits in the bearing recess. The patent describes the journal as having two or three fibers of wool yarn to wick the oil to the back bearing, and spiral grooves to return excess oil. The journal in the motor is just a simple piece of tubing with no evidence of wool remnants or grooves. The rear bearing depth is measured and is simply pushed out with a small drift.
All parts are cleaned in Zenith Formula 67 watch cleaning solution and rinsed twice in naphtha. The parts were left to dry overnight. The felt wick in the annular storage head is soaked in naphtha and pressed between pieces of a paper towel and repeated until the towels no longer show any residual color from the dirty oil.
The bearings are checked for wear by inserting the rotor arbor into the bearing and rotated to check for out-of-roundness. The rear bearing is fine, but the front bearing is worn. I reamed the hole out to accept a piece of oilite bronze, and drilled and line reamed the finished hole. Completed repairs and clean parts are ready for assembly, Figure K, the rear bearing is already inserted).
I placed the journal-tube in the rear bearing, oiled the juncture of the journal and bearing, oiled the recess in the front bearing, and pushed the front bearing in the body using dimensions recorded during disassembly. I placed synthetic clock oil in the journal and let the oil pull into the journal-bearing recess. I then pushed the arbor slowly in to push the remaining lubrication in the cavity, Figure L, which is actually the figurine motor) while blocking the back bearing. I next installed the annular storage head, and slowly added oil until it was nearly saturated, Figure M. I don’t believe that this fed much oil to the bearings. When I removed and cleaned it, most of the residual oil was still in the felt wick. I then inserted the rotor arbor slowly into the bearings, and then placed the rotor cup onto the arbor. I placed the gear end on a piece of Delrin on my bench block, and with a hollow punch, tapped the cup onto the arbor using the dimensions I recorded before disassembly.
The clock plates and parts were cleaned and serviced, Figure N, assembled, and the motor installed, Figure O. The mounting plate was added, Figure P, and then the completed assembly was test run, Figure Q. I let the clock assembly run for a couple hours to check for noise, and then added the dial, glass, and bezel.
Figure R shows the figurine mechanism. The motor turns a set of gears and levers, which causes the ballerina to rotate and move up and down. The gear train also runs the small music-box mechanism. Since this motor drives two mechanisms, a spinner knob is included to set them in motion when the power switch is turned on. Cleaning and oiling was all that was needed, along with cleaning and lubricating the music-box mechanism. Since this portion of the clock was usually just operated for special display purposes, it was in excellent, unworn condition.
By Bob Little, CC, CW