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 495 of 775

TM 9-2350-311-10

3-7 FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS

— CONTINUED

3-7.3

Leveling Gun Trunnions — Continued

a. Plumbline Method-Continued

15 Look through the breech bore sight (3) and check for proper alinement like B. Correct as required (steps

12 or 13).

16 Continue to elevate cannon tube (6) manually in 100 mil increments up to 600 mils, while observing

plumbline (4). Jack the weapon as required to keep vertical crosshair (14) parallel to plumbline.

17 Slowly depress cannon tube (6) to zero mils while observing plumbline (4). The crosshair should track

the plumbline. If it does, the gun trunnions are level. If it does not track, repeat steps 14 through 17 until

the proper alinement like B is obtained without moving the jacks (7). If plumbline cannot be tracked,

notify unit maintenance.

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