LOCODOC BELL ARMATURE (CORELESS) MOTORS:
Bell armature motors (also known as micro motors or coreless motors) are
a precision instrument motor that in many locomotives will offer the
very best performance possible. They are built completely differently than
can motors and have some different advantages and disadvantages.
The armature
of a bell armature motor looks like an empty can with one end cut out and
a shaft driven through the center of the other end. The walls of the can
are laminations of electrical wires lacquered together and attached
to the bottom of the can and shaft. This armature rotates inside the motor case
and around an internal magnet with the shaft turning in bearings
in the center of the magnet. The difference is that since there is no iron in the
armature, if you loose electrical power the motor freewheels and does not
brake to a stop like can motors. The light weight armature produces virtually no vibration, the gold
comutator and silver brushes provide almost silent operation and the low
current draw of these very efficient motors reduces wheel pitting. Since the armature
has very little mass it will have very
little inertia to overcome small binds and a light bulb will act as a dynamic
brake. A flywheel adds the necessary inertia and I order most
FAULHABER motors with double shafts to facilitate adding a flywheel to the back of the motor.
FAULHABER MOTORS
In years past
Faulhaber motors were usually mated to speed reducing gearheads for 1 - 10 MPH 2-8-0s
in HOn3 but the recent availability of slower and more powerful motors in the small
sizes makes direct drive gearing an attractive option instead of gearheads.
Bell armature motors tend to be more powerful
than comperable size can motors and are available in slower speeds which
sometimes match better to available gear ratios.
THESE MOTORS SHOULD NEVER BE RUN AT ABOVE THEIR RATED VOLTAGE.
The motor designation includes the metric size of the motor and the 12 volt speed
as this is critical in determining what motor to use to get the speed range you want.
| Motor # | 1319T7.4K | 1319T12.2K | 1319T15K | 1331T10.5K | 1524T9.9K | 1624T8.5K | 2020T3.6K |
| Diameter | .510 | .510 | .510 | .510 | .591 | .630 | .788 |
| Length | .797 | .797 | .797 | 1.270 | .937 | .980 | .788 |
| Price $ | 74.95 | 74.95 | 74.95 | 84.95 | 74.95 | 74.95 | 74.95 |
EXAMPLE; 1319T7.4K 1319 is the metric diameter and length, 7.4K is the
speed of 7400 RPMs at 12 volts
All double shaft motors have 1.5mm x 10 mm shafts out each end. The 15
and 16mm. motors should never have oil put on the brush end shaft as
there is no bearing here, only the comutator.
The 1331 motor is available only as single ended.
The 2020T has a built in 3.45/1 gearhead and will make a mild gear whine noise.
16/1 and 59/1 gear reductions are also available.
MAXON MOTORS
Until now there were no
high quality motors with enough power and sufficient speed to match big
steam locomotives with high gear reductions such as the PFM SF 2-10-4 and
4-8-4, the UP FEF-1, the WS SP GS-8 and the HM RI 4-8-4 and most newer
Tenshodo models. I have recently obtained some Swiss made Maxon
motors that are a 1640 double ended motor with a
14,000 rpm 12volt speed. They are long but the small diameter allows them to
be positioned foreward in the boiler and still leave room for a large flywheel
on the back of the motor. I call these the Maxon 1640T14K and they sell
for $79.95. I have had large diameter
Flywheels made to match their 1.5mm shafts.
NAMIKI MOTORS
Namiki motors were a Japanese made version of
a bell armature "coreless" motor. The 1220 (9500 rpm) and 1230 (7000 rpm)
versions were particulasrly well suited to HOn3 where the small size and low
speed made much better running locvomotives than other available motors of
the time.
The 1220 was used in several of the small PFM
HO and HOn3 shays such as the Herrington, MichCal#2 and others where the
motor was concealed in the tender and the drive to the cylinders was under
the cab deck. It was also used in the first run Key C-18 #318 and the C-19
#346 where it was just barely powerful enough.
The 1230 was a much more powerful motor and
was used with great successs in the Westside/PSC HOn3 C&S #74/75 2-8-0s and the
D&RGW "High Grade" C-16 with cab interior and motor in the boiler.
This drive was copied in the Key C&S #71
and RGS #42 C-17 and Nakamura West Side Lumber Co. shays (some with gearheads).
Westside also used this motor in larger locomotives (where it
was too small) like the HO Ma & Pa 0-6-0s, PRR D-16sb 4-4-0, the SP T-1 and
"Fire Train" 4-6-0s and the HOn3 "Craftsman" K-36 and K-28 2-8-2s where they
ran great but wouldn't pull a full train up a hill.
MOTOR FAILURES. Unfortunately many of these
motors were assembled with an inappropriate grease that hardened with age.
Some motors are completely frozen and
others take a high voltage to start and may squeal when run. This motor should
turn extremely freely at 1 volt DC, if at 2 volts it turns slowly like it is running in molasis
STOP NOW. Any of these symptoms will cause early failure of this precision motor.
In 2007 a dealer obtained the Namiki 1220 motors Westside had originally imported
for the S&S Limited NPC "Cab Foreward" HOn3 4-4-0 project and has been selling them
on Ebay. Unfortunately all I have seen have the hard grease problem and need rebuilding
before they are damaged.
REPAIRS; I have developed the tools, holders and
techniques to repair these motors. If you have problems Email me for advise in
your specific case. I also have fully reconditioned and guaranteed motors for sale
| Motor # | 1220T9.5K | 1230T7.0K |
| Diameter | .492 | .492 |
| Length | .868 | 1.187 |
| Price $ | 59.95 | 59.95 |
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