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 492 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

7

8

9

10

11

12

13

NOTE

Use wooden block (item 40, Appx D) at least 1 inch (2.54 cm) thick between jack and towing

pintle assembly.

Install jack (7) in center rear of vehicle with rear edge of jack pad under towing pintle assembly (9).

Release cannon tube (6) from travel lock and position turret lock in UNLOCKED position (para 2-10.8).

Turn on M145/M145A1 telescope mount (10) lights with toggle switch (11) and M15 elevation quadrant

(12) lights with toggle switch (13).

Manually position the cannon tube (6) at approximately zero elevation.

Look through the breech bore sight (3) and have someone manually traverse the cannon tube until the

vertical crosshair (14) on the muzzle brake (2) is alined next to the plumbline (4). If traversing more than

100 mils left or right is necessary, reposition the weapon or the plumbline.

If alinement looks like A, right front or right rear jacks (7) need to be jacked up until there is proper

alinement like B.

If alinement looks like C, left front or left rear jacks (7) need to be jacked up until there is proper

alinement like B.

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