M171 Telescope and Quadrant Mount

TM 9-1240-375-34&P

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M171 Telescope and Quadrant Mount

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M 171

Optical Instrument Support (1). The optical instrument support, located at the top of the M171 mount,

seats the M137/M137A2/M137A3 telescope.

Optical Instrument Rocker Assembly (2). The optical instrument rocker assembly houses the cross-

leveling mechanism. In conjunction with the elevation-leveling mechanism located on the housing

assembly, the optical instrument rocker assembly establishes the vertical axis reference for azimuth

compensation.

Worm Shaft Assembly (Cross Level) (3). The worm shaft assembly is located in the optical instrument

rocker assembly. The worm shaft assembly is actuated by a cross level knob. This assembly controls

the cant of the M171 mount.

Housing Assembly (4). The housing assembly houses the elevation-leveling mechanism and supports

the plunger assembly. The plunger assembly secures the M171 mount in an upright position on the

weapon. A spring-loaded guide is provided to prevent damage to the M171 mount if the elevation limit

of the instrument is exceeded.

Worm Shaft Assembly (Elevation) (5). The worm shaft assembly is located in the housing assembly. It

is actuated by the elevation knob.

Arm and Adapter Assembly (6). The arm and adapter assembly is located on the face of the arm

assembly, and supports the M17 quadrant. The mounting adapter provides the keyed interface for

assembling the M171 mount to the pre-qualified mounting adapter on the weapon trunnion. This

adapter also houses the bar. It serves as a reference about which the M171 mount is adjusted to

compensate in azimuth and elevation for the effects of trunnion cant.

Bearing Housing Assembly (7). The bearing housing assembly houses the bearings which permit the

smooth, compensating motion when the weapon is elevated. The stem holds the optical instrument

support, which seats the M137 telescope. It also provides the bearing in which the M171 mount is

cross and elevation leveled. Located at the base of the stem are the cross level vial and elevation level

vial.

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