The original came with a large open frame motor, mounted from one frame side rail on a bracket. The motor shaft, mounted worm drove an idler gear which in turn drove a gear on one axle with a 36:1 gear ratio. The remaining two axles were driven by a spur gear train along one side rail. Unfortunately the frame box was swage crimped together. The speed was close to 70 SMPH @ 12 V. For many years, I had searched for a method to slow the loco without tearing the frame apart. Discovering the Jameco #231731CA 5K RPM, flat can motor, presented the possibility to produce about 26 SMPH.
Note: Adjust brightness and contrast for optimum viewing.
New motor and bracket mounted on frame.
After drawing several methods, it was decided that the best soltion would be an "L" bracket sitting on the frame side rails for stability. Screwed to it and the side rails, brass angles would hold it in alignment.
First the bracket was bent from K & S .32" x 1/2" strip with legs 1.2" and .8". Coating with Dykem, a longitudinal center line was drawn on the short leg, along with a shaft center at .48" from the outside of the bend. Then the two screw centers were marked .244" from the center. The shaft center was drilled 9/32" and the screw hole at .090". Bending an exact 90 ° is difficult, thus requiring large clearance holes for final adjustment.
Note: Adjust brightness and contrast for optimum viewing.
XCAD LAYOUT DRAWING .
Frame is yellow.
motor is blue.
Since the new motor shaft was a little short and the NWSL worm fit loosely; for a more secure mount, a NWSL 2 mm to 3/32" bushing, partially filled with a short length of shaft rod was pressed part way into a 3/32" bore worm. This assembly was then pressed on motor shaft.
After determining correct polarity one terminal was soldered to the can rim and the pickup lead was soldered to the other. Then the motor was mounted in the bracket to determine the distances for the long leg and the angles.
Note: The motor requires 2 x .4 mm screws, no longer than 3 mm. Longer ones may damage windings.
The frame rails were .514" on the outside and .438" on the inside thus the .500" wide bracket would just rest on it at the edges. To center the strip, the angle would be set in (.5 - .438) / 2 = .031" from the edge. The 3/16" K & S angle was cut slightly shorter than the long leg and a center line was drawn on one face of the inside. Cross center lines were drawn about .4" and .76" from the bend end and center punched.. This was positioned clamped to the bracket leg, using a .032 strip as spacer. The holes were drilled through both pieces with a # 56 tap bit for #0 screws. Self tapping screws were run through the bracket holes and the angle holes were enlarged with a # 50 bit for adjustment clearance. The angle was screw to the bottom of the bracket leg and the assembly was placed on the rails for lateral alignment with the rails. The screws are accessible from the bottom between rails.
Next the motor was mounted to determine the longitudinal position. The existing side rail slots were used to scribe positions on the angle. The angle was punched at the center of the slot marks and drilled # 56 and tapped with screws. Loosening th motor slightly, the assembly was fastened to th rail while pressing the long leg against it.
Once aligned satisfactorly , the motor was positioned for proper gear mesh and secured. Examination revealed that a second angle was not necessary.
The total weight was just under 7 1/4 oz = 210 gm , so lead weight was added around the shell area.
