TM 9-129-357-15
quency of vibration is controlled by adjusting
piece and provides magnification of three power.
the rotation speed of the tester, as indicated on
Since there is no erecting system, an inverted
the frequency meter (fig. 4-6). This is accom-
image is seen. The telescope is carefully machined
plished by adjustment of the belt-driven varia-
and adjusted so that its optical axis is coincident
ble-speed pulley by means of the variable-speed
with its mechanical or geometric axis. The col-
handwheel. Amplitude is adjusted by the tee-
limating telescope is used to establish a horizontal
handled screw at the side of the vibrator. Refer
and vertical line by means of its own reticle to
to instruction and caution plates attached to the
test the aiming circle for reticle or image tilt.
vibration tester. A timer switch, wired into the
It can also be applied when testing the aiming
electrical circuits, is preset for the time of vibra-
circle for parallax, definition, and eyepiece focus.
tion required.
Tubular Wrenches
vibration tester adapter to mount the aiming cir-
cle. It is used to simulate conditions of shock
the tubular wrenches required for disassembly
and handling that the aiming circle would norm-
and assembly of the aiming circle and its equip-
ally encounter during its use. Through its use,
ment are identified in table 4-1.
loose dirt and improperly secured components
b. The tubular wrenches are used for removing
which would effect the efficient operation of
and installing the cells and retaining rings of
the aiming circle and revealed.
the aiming circle which are slotted to receive
b. Detailed Description. Amplitude and fre-
the lugs of the wrenches. Each wrench has three
quency of the vibrator and adjusted as required
pairs of 1/4-inch holes for the application of
a suitable bar for use in turning.
by the specifications of the aiming circle. Fre-
4-5
