ADAPTING ARTILLERY


SIGNS OF WEAR


Damage, such as cracks and holes, occurs during high-quadrant elevation, high-charge firings when the existing bump stops impact the firing platform. (Above photos courtesy of MAJ Wade Perdue, PM TAS)


To correct the damage problem, the Office of the Project Man- ager for Towed Artillery Systems (PM TAS) of the Program Executive Office for Ammunition, in collaboration with engi- neers at the U.S. Army Armament Research, Development and Engineering Center (ARDEC), developed a creative solution known as the Suspension Lock-Out System (SLOS), which PM TAS will begin fielding during the fourth quarter of FY15.


Te SLOS will not only alleviate holes and cracks on the lower carriage and the firing platform, but will also provide increased howitzer stability when firing all quadrant elevations with top- zone propelling charges, essentially allowing M119A3 crew members to provide more accurate and responsive fires. Quad- rant elevation is the angle between the level base of the trajectory and the axis of the bore when the howitzer is laid, or simply the elevation or depression of the howitzer gun barrel. Te quadrant elevation of the M119A3 ranges from -100 mils minimum to +1,244 mils maximum.


STRONGER DESIGN Te hardware for SLOS has three main components: struts and brackets, a fixed-recoil system and a titanium firing plat- form. Te struts and brackets are lightweight, titanium, easily installable and field-deployable mechanisms that attach to the lower carriage of the howitzer. Te SLOS kit removes the


64 Army AL&T Magazine October–December 2014


problematic variable-recoil hardware and replaces it with a fixed-recoil system. With the fixed-recoil system, the maximum recoil the operator will experience during operations, including high-angle, high-charge fire missions, will be 25 inches. With the variable-recoil system, the maximum recoil at maximum elevation is 14.5 inches, and the maximum recoil at minimum elevation is 42 inches.


Te fixed-recoil system translates into reduced firing loads on the carriage, thus increasing durability and reliability of the howitzer, and improves the rate of fire by significantly reduc- ing unwanted displacement, or the unwanted movement of a howitzer caused by the shock of firing. Such movement requires the crew to realign the howitzer to the gun target line after each shot fired. Reducing displacement means more responsive fires and less wear and tear on the howitzer.


Te titanium firing platform is an enhancement to the cur- rently fielded aging steel firing platform. Te legacy platform, made of aluminum and steel, is a multipiece assembly consist- ing of approximately 200 fasteners with significant welding. Tough this design has served the Army well since it first saw service with the 7th Infantry Division in 1989, recent com- bat operations in OEF identified the need for a stronger, more durable platform.


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