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 475 of 775

TM 9–2350–311–10

Change 3

3–71

3–6

ARMAMENT AND CAB MAINTENANCE — CONTINUED

3–6.8

Breech Mechanism — Continued

c.

Assembly

WARNING

The breechblock weighs approximately 125 pounds (57 kg). It takes two personnel to install the

breechblock to prevent injury to personnel.

1

Slightly raise operating cam (12) enough to clear rollers (11) from operating cam path. Rotate operating

crank assembly (71) to move gear rack and sector gear timing marks (72) to the center of the inspection

hole (73) in the carrier assembly (39). Scribe a line (73.1) from gear rack timing mark (73.2) onto carrier

assembly (39), insure line extends completely down and onto outer edge of carrier assembly. Slowly

lower operating cam to rest on rollers.

1.1

Scribe a line (73.3) from timing mark (73.4) onto breechblock (9), insure line extends completely down

and onto outer edge of breechblock.

12

11

71

72

73

39

73.2

73.1

39

73.3

9

73.4