TM-9-1240-401-34-P
TELESCOPE MOUNT M146: M118A2 AND M118A3; TELESCOPE MOUNT M145: M145A1; PANORAMIC TELESCOPE: M117 AND M117A2; FIRE CONTROL QUADRANT: M15; PERISCOPE: M42
TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL
JULY 1993
TM-9-1240-401-34-P - Page 28 of 590
TM 9-1240-401-34&P
1-5. EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES - continued
f.
M42 Periscope.
(1)
The M42 periscope is mounted above the cradle on the upper right-hand portion of the howitzer mount and is used
with the M118A2/M118A3 elbow telescope. It provides a clear field-of-view when the gun muzzle brake is used. The M42
periscope consists of two clear windows, a stationary mirror, and an adjustable mirror mounted in a housing.
(2)
The windows are mounted in the housing and secured with sealing compound. They pass the image to and from
the mirrors with a minimum optical distortion. The stationary mirror is cemented to a plate which is mounted on the left side of
the housing. The adjustable mirror is secured to a cover assembly which is mounted on the right side of the housing. The
cover assembly contains provisions for adjusting the position of the mirror to obtain minimum image tilt and collimation.
1-6. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS
Refer to paragraph 1-5, Equipment Characteristics, Capabilities, and Features for external components.
1-18
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