• M1 & M1A1 Quadrant

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      QUADRANT, FIRE CONTROL:gunner’s M1 or M1A1, is a portable precision leveling instrument used for laying artillery weapons in elevation, for measuring their angles of elevation and for checking the adjustments of elevating mechanisms on sight ing and fire control equipment. It consists of a sector-shaped frame to which is pivoted a leveling radial arm carring a level vial tube assembly. Four frame shoes, arranged in pairs, provide two reference surfaces at right angles to each other for seating the instrument when taking readings. Machined teeth on the inside are of the frame, engaging with a spring-loaded plunger in the radial arm, permit rapid setting of the arm in coarse 10-mil steps, as read on elevation scales provided on each side of the frame. The left scale is used for elevations from 0 to 300 mils, and the right scale is used for elevations from 800 to 1,600 mils. The leveling radial arm has a micrometer graduated in 0.2 mil steps which provides fine adjustment. By the use of the coarse and fine motions, the level can be set to the required angle. When the level bubble is centered, elevation is read as the sum of the coarse and fine scale readings. An arrow with instructions “LINE OF FIRE” is scribed on the frame to indicate the direction the instrument is to be faced and the correct reference surface for  the scale in use. The gunner’s fire control quadrant M1 or M1A1 is used with various rifles, guns, gun carriages, self-propeiled guns, gun motor carriages, antiaircraft gun mounts, cannons, cannon and carriage transport vehicles, sombat tanks, tracked armored landing vehicles, multiple rocket launchers.


    Differences among models

      the models differ in the design of the radial arm plunger plates. The gunner’s fire control quadrant M1A1 differs from M1 in that it has a micrometer mask and a micrometer mask key on the leveling radial arm.





    Elevation scales:

    Lower 0 to 800 mils;Upper 800 to 1,600 mils

    Limits of Operation:

    Elevation 1,600 mils;Depression 0


    67/8 in


    11/16 in.


    6 in.


    1.8 lb