IBM Selectric Maintenance Manual page 114

A worn pawl will be notched and polished at point
"All.
ESCAPEMENT PAWL
Figure 3.1
3.9 S.H. CARRIER RETURN SPRING CLUTCH
3.10
Under no circumstances should the carrier return
spring clutch be lubricated with grease or oil. The
only recommendation made by Engineering for lub-
rication in this area is a very light film of oi I to
be placed on the outside surface of the spring clutch
to prevent rust.
If the carrier return spring clutch becomes contam-
inated with grease or oil, several intermittent car-
ri er return prob lems wi II resu It.
1. Uneven LH margin due to fai lure of spring
clutch to di sengage on its arbor.
2. Sluggish tab or print escapement due to the
contamina.tion not allowing the spring clutch to
fully release the pinion.
3. Oscillating carrier motion when machine is
idling due to contamination causing spring
clutch to engage and disengage erroneous Iy.
S.H. MAIN SPRING
Effective with I/O Printer
SIN
4607171. all Se-
lectric I/O printers will incorporate a 100" main-
spring.
The old 75" mainspring, PN 1124519, will no long-
er be used. The new 100" mai nspri ng, PN 1164342,
will be available for field replacement and is di-
rectly interchangeable with the old 75" mainspring.
The new 100" mainspring may easily be identified
by the "100" stamped on the rear of the mainspring
cage.
This new spring wi II add greater torque to the car-
ri er escapement and tab operati ons.
. 3.11 S. H. ESCAPEMENT RACK
4-6
ihe pawl holding angle has been increased to im-
prove escapement pawl life. The angle of inclina-
tion for the SELECTRIC I/O production escapement
rack teeth has been reduced to 14°. This change
has the effect of an increased escapement pawl to
escapement rack holding ang Ie, without necessita-
ting a major change of design or of adjustment.
The 14° escapement rack has a milled notch (Fig.
A) on the LH end. The new part numbers are listed
below and should be added to your Keyboard or
Keyboardless I/O Printer Parts Catalog.
Identification Notch
Figure 3.2
\
Part No.
1124083
1124109
1128032
1128037
Adjustments
Desc
ri
pt i on
Rack, lOP, 11 in.
Rack, 12P, 11 in.
Rack, lOP, 15 in.
Rack, 12P, 15in.
14° escapement racks should be installed parallel to
the print shaft. Measure the distance between the
rack and the print shaft at each end, using a Hoover-
ometer as shown in Fig. B. Set the Hooverometer to
the #2 scribe line. The correct distance is achieved
when the handle of the Hooverometer rests with its
mid-point against the front edge of the escapement
rack.
Escapement Rack
Figure 3.3