IBM Selectric I/O Manual Of Instruction page 75

Torque Limiter Hub Sleeve
C. R. Clutch Arbor
C. R. Clutch Spring
Torque Limiter Spring
Carrier Return Pinion
FIGURE
144.
Torque Limiter - Exploded View
The operational shaft turns in the unwinding direction of the
torque limiter spring. This tends to expand it allowing it to
slip. The spring is heavy and considerably smaller than the
carrier return clutch arbor over which it fits. The friction
present between the arbor and the spring tends to drive the
arbor even though it is in the unwinding direction of the
spring. However, insuffi cient driving force is obtained from
this arrangement.
The right end of the torque limiter spring is formed into an eye
to accept an extension spring connected from the eye to an
eccentric adjusting stud on the torque limiter hub (Figs.
143
&
144). The extensi on spri ng increases the force requ i red to
unwind the torque limiter spring so that no slippage occurs
during normal carrier return. The torque limiter spring slips
when the carri er cannot move to the left. It a Iso s lips at the
beginning of a carrier return operation to allow smooth ac-
celeration and prevent a jerky start.
~
Carrier Return - Late Style 11 Inch Mach ines
•
The carrier return operation remains the same. Parts have been •
re-designed to provide easier accessibility for adjustments and
will hold these adjustments longer.
The transfer of motion has changed in the operational latch
mechanism (Fig. 144.1).
When the carrier return operational latch is pulled down by
, the cam follower, the latch arm presses the carrier return lever
, down. A stud on the carrier return lever fits in a slot of the
intermediate latch actuating arm, and as the lever moves down
it rotates the arm and pivots the carrier return latch pin and
dutch latch. As the carrier return latch moves downward, it
rotates the latch actuating arm which contacts the escapement
torque bar causing the escapement pawl to be removed from
its rack. Further motion causes the clutch latch to be held in
, the operated position by the latch keeper.
58
Pivot Pin
~
LatchArm'~
Assembly
"W
Intermediate Latch Actuating Arm ,
FIGURE
144.1
Carrier Return (Late)
Attached sol idly to the left side of the latch actuating arm and
rotating with the arm is the pivot pin for the operational latch -
es (Fig. 144.1). As the operational pivot pin rotates, the car-
rier return clutch arm attached to its left end moves up, forc-
ing the carrier return shoe into the spring clutch.(Fig.
144.2).
FIGURE
144.2
Carrier Return Shoe (Clearance)
The carrier return mechanism remains latched in the active
position until the carrier reaches the left margin. At that
time, the clutch is unlatched and the escapement pawl is al-
lowed to restore back into the rack.
Carrier Return (15 In .)
The following section concerns the operational section of the
carrier return mechanism on the long carriage machines. This
section of the mechanism is different than that of the 11 in.
printer because of the longer carriage.
The carrier return operational latch is mounted on the carrier
return latch arm which pivots freely about a pivot pin mounted