TM-9-2350-311-20-2
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS
DECEMBER 1993
TM-9-2350-311-20-2 - Page 262 of 828
TM 9–2350–311–20–2
5–6
5–3
FIRING MECHANISM ASSEMBLY, M49 (M284 CANNON) — CONTINUED
a.
Disassembly — Continued
5
Remove two springs (10 and 11), sleeve bushing (12), and spring (13).
NOTE
Firing mechanism contains three bearing balls. Be careful that bearing balls are not lost during
disassembly.
6
Separate hammer guide yoke (5), three bearing balls (14), firing hammer (15), and access cover (16).
b.
Inspection
Inspect for broken, burred, and missing parts. Replace as required.
c.
Assembly
1
Install firing hammer (15) in access cover (16).
2
Install hammer guide yoke (5) on firing hammer (15) so groove in firing hammer lines up with holes in ham-
mer guide yoke.
NOTE
Apply GAA to holes in hammer guide yoke before installing bearing balls.
3
Install spring (13) and sleeve bushing (12) on hammer guide yoke (5) and install three bearing balls (14) into
hammer guide yoke holes between coils of spring. Slide sleeve bushing against spring until spring is fully
compressed against the access cover (16).
4
Pull firing hammer (15) from hammer guide yoke (5) until sleeve bushing (12) locks in place.
5
Set yoke and hammer group on socket so firing hammer (15) hangs freely.
6
Assemble two grooved pins (8) and two retaining rings (7) in case (9), if disassembled.
7
Install two springs (11 and 10) over hammer guide yoke (5).
8
Install assembled case (9) over two springs (11 and 10).
9
Install follower (2) over assembled case (9) alining pins with cutouts of follower.
10
Using M34 fuzesetter, compress two springs (11 and 10) and follower (2) over hammer guide yoke (5) until
manual control lever (4) can be inserted into hammer guide yoke.
11
Install grooved pin (3) in manual control lever (4) and hammer guide yoke (5).
12
Depress firing hammer (15) against solid flat surface to seat firing mechanism (1).
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