EQUIPMENT DESCRIPTION AND DATA -820360023

TM 9-1240-375-34&P

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DIRECT SUPPORT AND GENERAL SUPPORT

EQUIPMENT DESCRIPTION AND DATA

EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES

M17/M17A1 and M18/M18A1 Fire Control Quadrants: The dual fire control quadrants are identical

with the following exceptions. The M17/M17A1 quadrant contains a left-hand worm shaft assembly and

gear, and the M18/M18A1 quadrant contains a right-hand worm shaft assembly and gear. Also, the

M18/M18A1 quadrant features a cross level vial, which is not present on the M17/M17A1 quadrant. Both

quadrants have the capability of measuring elevation to 1433 mils. The dual equipment permits either the

assistant gunner or the gunner to lay the cannon in elevation. The counters and level vials are self-

illuminated with radioactive tritium H3 in the M17 and M18 quadrants and illuminated by battery power in

the M17A1 and M18A1 quadrants.

M171/M171A1 Telescope and Quadrant Mount: The M171/M171A1 mount supports the

M137/M137A2/M137A3 telescope and the M17/M17A1 quadrant. The M171/M171A1 mount is installed on

the left trunnion of the howitzer. It provides an adjustable base for leveling the M137/M137A2/M137A3

telescope and the M17/M17A1 quadrant. The adjustable base compensates for azimuth and elevation errors

introduced by cant when the weapon is elevated. The M171 level vials are illuminated by tritium H3 and

the M171A1 level vials are illuminated by battery power.

M172/M172A1 Telescope and Quadrant Mount: The M172/M172A1 mount supports and provides an

adjustable base for leveling and boresighting the M138/M138A1 telescope and the M18/M18A1 quadrant.

The M172/M172A1 mount is installed on the right trunnion of the 155-mm howitzer.

M137 Panoramic Telescope: The M137 telescope is a 4-power, 10-degree field of view instrument with

digital counters. All counters and the reticle of the M137 telescope are self-illuminated by radioactive

isotopes. The M137 telescope is the basic instrument used in laying the M198 howitzer in azimuth. The

M137 telescope is mounted to the upper part of the M171 mount. This instrument is hermetically sealed

and can be purged with dry nitrogen.

M137A2/M137A3 Panoramic Telescope: The M137A2/M137A3 telescope is a 4-power, 10-degree field of

view instrument with digital counters. All counters and the reticle of the M137A2/M137A3 telescope are

self-illuminated by lithium batteries. The M137A2/M137A3 telescope is the basic instrument used in laying

the howitzer in azimuth. The M137A2/M137A3 telescope is mounted to the upper part of the M171/M171A1

mount. This instrument is hermetically sealed and can be purged with dry nitrogen.

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