TM-9-2350-311-10
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; OPERATOR’S MANUAL
NOVEMBER 1994
TM-9-2350-311-10 - Page 487 of 775
TM 9-2350-311-10
3-7 FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS—CONTINUED
3-7.2 M1A1 Gunner’s Quadrant Tests
a. Micrometer Test
1
Inspect the elevation seats (1) on breech ring for dirt or burrs. If necessary, clean with a wiping rag (item
35, Appx D). If burrs are present, notify unit maintenance.
2
Set index arm (2) of Ml Al gunner’s quadrant (3) at plus 10.
3
Set the micrometer knob (4) at zero.
The breechblock must be open and the operating handle left unlocked. To prevent injury to
personnel, be careful not to lift up on operating cam before securing operating handle after
leveling cannon tube.
4
Unlatch operating handle (5) enough to place M1A1 gunner’s quadrant (3).
5
Position M1A1 gunner’s quadrant (3) on breech with LINE OF FIRE arrow (6) pointing toward muzzle.
6
Depress or elevate cannon tube to center bubble (7).
7
Set index arm (2) at zero.
8
Set micrometer knob (4) at 10.
9
Position M1A1 gunner’s quadrant (3) on breech with LINE OF FIRE arrow (6) pointing toward muzzle.
10
Bubble (7) should center. If bubble centers, micrometer test is complete. Proceed to end-for-end test
(para 3-7.2b.). If bubble does not center, the micrometer is in error and should be turned in to unit
maintenance for repair.
NOTE
Breech is completely closed when witness marks on breech ring and breechblock aline.
11
If necessary, open breech and close completely.
3-83
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