Motor And Drive - IBM Selectric I/O Manual Of Instruction

MOTOR AND DRIVE
The motor used in the Selectric I/O Printer is a three-inch
shaded pole, induction type: motor that requires 115 volts,
60 cycles A. C. (Fig. 1).
I~
is rated at 1/35 h .p. The motor
is mounted at the left rear corner of the machine with the
pulley toward the right. It is attached to an
ad~ustable
bracket at each end by ring shaped spring retainers that en-
eirc Ie the rubber motor mounts.
3" Shaded Pole Motor
Motor Pulley and
Clutch Mechanism
FIGURE 1. Shaded Pole Motor
The motor may be removed easi Iy after snapping the retainers
off the brackets. With the belt removed the right end of the
motor may be moved to the rear, and the motor may be removed
toward the right. With this bracket design, the force of the
motor in operation is against the bracket rather than against the
retaining cl ips.
The motor bearings are babbit inserts pressed solidly into the
motor end bells. Each bearing is completedy surrounded by a
saturated oil wick. Asmall square wick fits into a notch inthe
top of each bearing to supply oil directly
11'0
the rotor shaft.
1
It should seldom be necessary to disassemble the motor; however,
care should be taken in replacing either end bell that is not in-
vertedwhen installed. The oil hole in the left end bell and the
notch in the bearing would then be on the bottom.
The starting torque for the motor is provided by the shaded
pole principle. No capacitor is required.
The motor has an internal circuit breaker to prevent damage to
the field coil in the event the switch is left ON with the ma-
chine stalled. The circuit will open only if the motor is allowed
to remain stalled for a period of time; therefore there is no
dangerof an open circuit during normal operation. The motor
will stall only in rare cases where a maladjustment or parts
breakage causes the machine to lock. After the motor has re-
gained normal temperature, the circuit breaker wi II again close
the circuit. The circuit breaker will continue to open and close
as long as the motor is stalled and the switch is left ON.
Because of its design, the shaded pole motor tends to run at a
higher temperature than other IBM typewriter motors. Core
should be taken in handling the motor to prevent being burned.
In order to prevent over-heating, a cool ing system is incorpo-
rated in the design of the motor. A fan attached to the right
end of the rotor pulls air through the left end bell and across
the field coi Is. The air is then discharged through a duct at
the right rear corner of the motor. The air escapes through a
grill in the rear of the machine cover. The hot air being dis-
charged pulls cool air with it from within the machine. The
air that ultimately emerges from the machine is cooled to near
room temperature so that no objectionable heat results.
The three wire grounded system has the third line cord lead
attached to the powerframe at the cord c Ii p screw. A short
jumper wire is connected between the motor and powerframe
(Fig. 2).
White
Green
Solderless Connector
Black
Plug
Switch
FIGURE 2. Shaded Pole Motor Diagram
In some Selectric I/O Printers, a capacitor-start induction
type motor is used (Fig. 3). A capacitor, in the starting
winding circuit, provides a starting torque for the motor and
controls the direction of rotation. The capacitor also re-
mains in the circuit whi Ie the motor is running. The capaci-
tor is mounted in a vel:tical position by a bracket at the right
rear corner of the machine.