109 FAMILY OF HOWITZERS

Information Page

DESCRIPTION

The howitzer is a vehicle that provides armored combat support, is air transportable, internally loaded, and has excellent ground mobility. It allows firing in a 360 degree circle through its primary armament, the 155mm cannon assembly, and its secondary armament, the M2 heavy barrel caliber 50 machine gun. The system is capable of both direct (line of sight) and indirect (out of the line of sight) firing.

1  M185 Cannon (M109A2/A3/A4)
   M284 Cannon (M109A5)
2  Caliber 50 Machine Gun, M2
3  Panoramic Telescope Shield and Indirect Fire Telescope
4  Cannon Mount M178 (M109A2/A3/A4)
                M182 (M109A5)
5  Cab
6  Hull
7  Direct Fire Periscope

PERFORMANCE SPECIFICATIONS

WEIGHT:

Classification

Empty...................................................................52,000 lb (23,586kg)
Combat Loaded....................................................55,000 lb (24,948kg)

WIDTH

Overall.................................................................124 in.(3.1M)

HEIGHT

Overall.................................................................120.43 in(3M)
Lowest operable height........................................109.93 in(2.8M)
Ground clearance.......................................................18 in(0.45M)

LENGTH

M109A2/A3/A4 w/armament...................................359.38 in(9.12M)
M109A5 w/armament..............................................361.38 in(9.17M)
M109A2/A3/A4/A5 w/o armament..........................243.75 in(6.19M)

SPEEDS

High Speed..........................................35 mph (56.3kmph)
Low Speed............................................6 mph (10kmph)
Range..................................................217 miles (349km)

PRIMARY ARMAMENT (TWO CONFIGURATIONS)

Cannon assembly.........................................................................M185 (M109A2/A3/A4)
....................................................................................................M284 (M109A5)
Cannon Tube Length....................................................................238 in. (6.05m) (M185)
....................................................................................................240 in. (6.09m) (M284)
Cannon Mount.............................................................................M178 (M109A2/A3/A4)
....................................................................................................M182 (M109A5)
Maximum Range (M109A2/M109A3/M109A4)..........................18,000m
....................................................................................................RAP 23,500m
Maximum Range (M109A5).........................................................22,000m
....................................................................................................RAP 30,000m
Maximum Rate of Fire..................................................................4 rds/min for 3 min
Sustained Rate of Fire..................................................................1 rd/min for 60 min
...................................................................................................1 rd/ 3 min thereafter
SECONDARY ARMAMENT
Machine gun................................................................................Caliber 50, M2, Heavy barrel

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The King of Battle!

The large interrupted screw type breech has been opened and hangs to the right of the breech ring. The power rammer is in position directly behind the breech opening, ready to ram. The handle to the top of the breech is used to open the breechblock when it is closed. The operating cam used to close the breech is located directly above the opened breechblock. The tube traversing to the right next to the gun is the Assistant Gunner's elbow telescope M118A2, used for direct fire. Behind the telescope is the Gunner's quadrant M15 and behind that is the bottle reservoir (nitrogen tank) for the replenisher accumulator system. To the right of the bottle is the Assistant Gunner's oddment tray welded to the wall of the cab and above tray is a bracket for stowing a flashlight and a bin for a spare periscope. Up above these is one of the interior light boxes. Notice the number of hydraulic lines on the ceiling that feed all the power mechanisms around the gun.

As the Tube fires and Recoils, a cam follower attached to the Breech Mechanism, makes contact with the Cam Arm. This action then turns the Breech- block, Counter Clockwise to disengage the Interrupted Screw Lands, and swings the Breechblock to the locked open position.

Once the Projectile and Propellant are inserted, the Cannoneer raises the Cam Arm and the Breechblock swings shut and turns Clockwise to engage the Interrupted Screw Lands to the locked closed position, ready for firing.

Breech Block

Breech Opening Cam Arm

This drawing shows the rammer in the up and ramming position (top) as well as the stowed position. When not in use the rammer assembly is stowed under the breech assembly. The handle (10) is pulled to release the rammer assembly and tray and it is then pulled back behind the breech and folded up into position. The rammer tube is then released by pulling another handle (11) and folded to the left, exposing the rammer tray. The round is then placed onto the tray and pushed by hand most of the way into the breech. The rammer is folded back into position and the control handle located on the cab roof pushed forward. This activates the hydraulic cylinder in the rammer and seats the round completely into the breech. Once the rammer is released and folded back out of the way, Cannoneer No. 1 receives the proper propellant charge and loads with the red igniter end is toward breechblock. Assuring the red igniter pad is visible the soldier then closes the breech, adds a small M82 primer, pulls closed the firing mechanism block assembly and attaches the firing lanyard.

These pictures show the rammer attached to the gun. In the older models, the Rammer and Loading tray was attached to the frame, folded up behind the Cannoneer and in line with the breech. When the tray was to be used, it unfolded and adjusted to align with the breech, the projectile was then placed on the tray and the Rammer pushed it all the way to the seating position. The tray was then refolded and the procedure was as above. The Rammer setup as shown above is a vast improvement.