127K9720

Japan Servo 127K9720  

This is a little 24V brushed DC servo originally intended for canon copier machines that I plan on using in the prototype hexapod. I believe this is a coreless pancake type motor; read all about it here
http://kmtg.kollmorgen.com/products/motors/pancake/servodisc/advantages.html and here
http://kmtg.kollmorgen.com/products/motors/pancake/servodisc/design.html

These little guys have a 4.1" square base with mounting holes in a 3" square bolt pattern. It comes with an oddly shaped piece of metal attached to the motor with a pivot hole and slots (4" pivot radius) used for adjusting belt tension.

The motor body is in two sections, one made of stamped steel, the other of cast aluminum or pot metal. The stamped steel section is 0.625" tall and just under 4" in diameter, and made of 0.059" sheet steel. There is a raised nub on the side the wires exit the motor that could cause problems if mounting the motor flange from underneath. On the pulley side (bottom) there is a 1.4" diameter 0.165" tall nub with another 0.825" diameter by 0.125" tall nub on top of it, which holds the shaft bearing. The shaft has press-fit on it a 0.75" diameter 0.54" tall die-cast 30 tooth MXL timing pulley with 0.943" diameter by 0.054" thick flange.

The cast section is 0.5" thick and 3.23" diameter. It is attached to the stamped section with three machine screws and is centered by three raised arc-shaped nubs. A red and a black wire come out of a rubber 0.225" x 0.493" x .940" translucent plastic connector with two D-shaped (like an ATX power connector) sockets. A tamiya connector might work for this, if filed down a bit.

On top of the cast section is a 1.062" tall 2.20" diameter black plastic encoder cover, secured by 3 radial (#4-40?) philips screws to a 0.35" tall 2.125" diameter raised hub on the cast section. This cover is rather fragile; I broke it when I accidentally knocked the motor off my desk.

The encoder cover is marked:

DC SERVO MOTOR
DF10BE22-01 DC 24V
127K9720 No. 201
JAPAN SERVO CO., LTD TOKYO JAPAN

The encoder ring is glued to a set screw hub bolted to the 0.236" shaft. The encoder sensor is mounted to a round circuit board that just connects it to a 4 wire cable. The cable has a connector that is exactly like a CD-ROM audio connector. There are 4 gold pins on 0.1" centers in a row. Starting with the pin with an arrow pointing to it, we have: Vcc (white), A (green), B (red), GND (black). The encoder cable has a rubber sealing grommet that fits in a 0.316" slot in the plastic cover. The outer diameter of the grommet is about 0.45". There is also a 1.12" long by 0.55" OD by 0.25" ID ferrite bead surrounding both the encoder and motor power wires about 1" from the connectors. The poewr wires are 5" long and the encoder wires are 5.5" long and 0.2" thick (due to shielding?) and the discrepancy gives the two cables a nice bend of about 90 degrees.

The motor coils are about 10 ohms.

From the catalog: Rated at 24 VDC, 2700 �}270 RPM, 22 watts, 0.9 amps, torque 11 in-lb. 12V DC, 1300 RPM, torque 6 in-lb. CCW rotation. Optical encoder: 2-phase, 500 pulse/rev/phase; TTL logic; requires 5V DC supply @50 mA. Includes wiring diagram. Shaft size 0.225 dia. x 5/8" L with press-fit aluminum gear, easily removed. Motor size 4" dia. x 2-1/4"L with 4"sq. face plate.

These motors are available from Jon Elson here and also from an ultra-top-secret source known only to a select few..