MIL-DTL-48556 Quadrant, Fire Control - M18A1This specification covers Quadrant, Fire Control: M18A1, which provides a measure of elevation angles for 155mm towed howitzers. It is equipped with numerical counters which indicate elevation settings and corrections.

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MIL-DTL-48556B

TABLE II. Knob torque.

Knob

Torque at

+60�F to +90�F

+145 � 5�F

-50 � 5�F

Elevation

3 to 10 inch pounds

13 inch pounds

maximum

Correction

1 to 4 inch pounds

8 inch pounds

maximum

3.10 Counter numerals. With the unit digit of each counter centered in the aperture

of the cover, the remaining numbers shall be in alignment within 1/16th inch.

3.11 Level vial illumination. With fresh batteries installed and the light turned on,

the level vial bubbles and markings shall be clearly distinguishable when observed in

ambient light conditions ranging from dusk into night.

3.12 Counter illumination. With fresh batteries installed and the light turned on, the

numerals on the elevation and correction counters shall be clearly distinguishable when

observed in ambient light conditions ranging from dusk into night.

3.13 Interchangeability. The quadrant shall be able to be installed on any M172A1

mount that is within specification.

3.14 Workmanship. Workmanship of the quadrant shall be in accordance with the

requirements of MIL-F-13926.