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 501 of 775

TM 9–2350–311–10

Change 3

3–97

3–7

FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS — CONTINUED

3–7.5

Leveling the Cannon Tube — Continued

b.

Leveling the Cannon Tube Using the M1A1 Gunner’s Quadrant

NOTE

•

Top surfaces of cannon tube quadrant seat must be free of paint prior to being used for

taking readings with M1A1 gunner’s quadrant.

•

The cannon has quadrant seats on the top muzzle brake end of the cannon tube and on the

top of the breech ring. The embedded correction (the difference between muzzle and

breech elevation) is measured rather than being stamped on the breech. Breechblocks that

have stamped embedded corrections should be disregarded during cannon tube leveling

test.

1

Place a tested M1A1 gunner’s quadrant (13) on the top surface of cannon tube quadrant seat (17).

Apply only the M1A1 gunner’s quadrant correction, if any, and center the elevation bubble (3) by

manually elevating or depressing the cannon tube (2). The cannon tube is now at 0 mils.

17

Top Surface

Bottom Surface

13

2

3