IBM Selectric I/O Manual Of Instruction page 85

The tab lever is operated to the rear by the tab torque bar.
The tab lever is a small lever pivoted on the top of the es-
capement bracket at the rear. The tab lever releases both
the escapement and backspace pawls from their racks and
holds them in the released position. As the tab lever pivots
toward the rear, a I ug at the front of the tab lever contacts
the escapement and backspace pawls and forces them to the
rear out of mesh with their racks (Fig. 166). A small latch
pivots on the escapement bracket at the right end of the tab
lever. When the tab lever has moved far. enough to the rear
to release the pawls, the tab latch swings into a notch in the
tab-lever assembly to hold it to the rear,' tl)us latching the •
pawls out of their racks (Fig. 167). A torque bar lockout tab
on the tab lever holds the torque bar to the rear as long as
the tab lever is latched out (Fig .• 168) • This is necessary
to keep the tab Interlock contact operated for the duration
of a tab cycle.
Tab Torque Bar
FIGURE 167. Tab-Latch Operation (Early)
Tab Lever
FIGURE 168. Torque-Bar Lockout Tab (Early)
Late Level
The late tab mechanism operates very similar to the early. In-
stead of the torque bar contacting the tab lever lug it con-
tacts a trigger which, in turn, moves the tab lever to the
rear (Fig. 169).
The trigger also has an upright lug toward the front (Fig. 169),
which takes the place of the lockout tab (Fig. 168). The rest
of the tab operation is the same on both old and new mecha-
nism except the interlock contact which is covered under a
separate heading.
66.1