IBM 727 Manual Of Instruction page 53

screws for the angle clamps too tightly, as they can distort the shape of the clamps
and lucite.
The columns are adjustéd to be parallel to the lower main plate.
chines (two holding screws to the lower main plate), adjust as follows: remove the
lucite cover angle clamps and loosen the two manifold mounting screws at the base;
position the columns so that dimensions (A) and (B) are within .005" of each other.
On the later machines (with four holding screws to the lower main plate), the
above adjustment is set at the factory.
columns when tightening the manifold to the base.
Adjustment of the columns with respect to the lower main plate is not impaired
by the removal of the angle clamps and lucite cover for cleaning purposes,
15. 6. 2 Adjustment of Vacuum Safety Switch
With power on the vacuum motor and tape in columns, turn the adjusting screw
clockwise until the switch transfers, stopping the drive m otors.
adjusting screw until the switch again transfers, and continue backing one turn farther.
When the vacuum is turned on without tape in columns, the vacuum safety switch
should not transfer from its depressed position until both flapper switches have trans­
ferred to their rear positions.
15. 6.3 Adjustment of Flapper Valve Switches
Adjust right and left flapper valve switches so that they are depressed and make
with at least 1/16" overtravel at the actuating roller when vacuum is on and tape is
removed from the column being adjusted.
the minimum amount of tape required to seal that column is inserted. Any leakage in
the vacuum columns seriously affects correct operation of the flapper valves.
1 5 .6 .4 Adjustment of Vacuum Column Switches (Figure 11)
Loosen the adjusting nuts and form the upper contact straps to provide 1/64"
rise of strap from support at (1) when the center strap is at rest.
support for . 020" (+ . 010", - . 000") gap between lower points at (2).
provide 1/64" clearance at (3) when diaphragm is at rest.
threads of push rod to prevent damage to diaphragm when adjusting.
The lower contacts should have 3/64" travel after making if push rod is depressed
until diaphragm bottoms.
normal operating point makes and vice versa. A careful reform ing of contact straps
in addition to adjusting nuts is perm issible to obtain these results,
1 5 .6 .5 Removal of Vacuum Pump
Remove the vacuum pump as follows:
1. Loosen clamp on vacuum hose at manifold.
2 0 Separate vacuum motor plug.
Be sure not to bend the lower portion of the
Change the above adjustment if necessary.
The switch should release and break when
Both normally closed points should break before either
53
On earlier ma­
Back off on the
Adjust lower
Adjust nuts to
Be sure nuts are free on
Pull hose from manifold pipe.