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 122 of 828

TM 9–2350–311–20–2

3–13

b.

Cannon

The cannon consists of the muzzle brake, thrust collar, cannon tube, bore evacuator, mount, variable recoil mechanism,

breech assembly and firing mechanism. Below is a pictorial view of the cannon with all the major assemblies installed. The

muzzle brake and variable recoil mechanism reduce and absorb the recoil of the cannon tube during the firing sequence.

The breech assembly houses the projectile and propellant during a firing. The firing mechanism is used to fire the cannon.

THRUST COLLAR

BORE EVACUATOR

UPPER GUN ROTOR

MUZZLE BRAKE

TUBE

BALL VALVES

DUST SHIELD

RECUPERATOR

LOWER GUN SHIELD

HOWITZER MOUNT

TRUNNION BEARING

RECUPERATOR

BUFFER CYLINDER

BREECH OPERATING CAM

VARIABLE RECOIL MECHANISM

CANNON