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TM 9-254
3-8.
Level Vials - Continued
h.
Installation of Three Piece Eccentric and Level Vial Tube (fig. 3-25). The proper method for installing a level
vial tube and three piece eccentric is as follows:
Caution
The straight pin must not protrude more than one-sixteenth of an inch into the vial hole.
NOTE
Check level vial tube (4) on surface plate to insure that the bubble is within 1 to 1-1/2 graduations
of being level before installing into the rocker and cover.
(1)
If removed, press or drive straight pin (2) into bonded and machined rocker (3) so that the straight pin
protrudes far enough into the level vial hole to engage the level vial tube.
(2)
Position the level vial cover (1) into bonded and machined rocker (3). Slide the level vial tube (4) into the
rocker and cover so the slot in the end of the level vial tube engages the straight pin (2).
(3)
Install eccentric (5), eccentric ring (6), and plug (7) into machined rocker (3) but do not tighten pending
final adjustment.
i.
Final Adjustment of a Three Piece Eccentric and Level Vial Tube (fig. 3-25). The final adjustment of the level
assembly is performed after it has been installed on the instrument and set up on the cross-leveling and elevation fixture.
(1)
Engage fabricated eccentric tool (8) into eccentric ring (6) and plug (7).
(2)
Insert a common straight blade screwdriver (9) through the center hole in the fabricated eccentric tool (8)
and engage eccentric (5).
(3)
Adjust eccentric (5) and eccentric ring (6) until the level vial bubble is centered within the graduations on
the level vial tube (4).
(4)
Rotate level assembly from 0 mils to 1330 mils and adjust eccentric (5) and eccentric ring (6) until the
level vial bubble is centered within the graduations on the level vial tube (4).
(5)
Rotate level assembly from 1330 mils to 0 mils and adjust eccentric (5) and eccentric ring (6) until the
level vial bubble is centered within the graduations on the level vial tube (4).
(6)
Repeat steps (4) and (5) as necessary to level the vial at 0 mils and 1330 mils.
(7)
Hold the inner portion of the fabricated eccentric tool (8) firmly in place while turning the outer portion of
the fabricated eccentric tool to tighten plug (7). Be careful not to disturb the setting of level vial tube (4).
3-25
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