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M113 Conversion

The M113A1 conversion packages provide increased crew safety by replacing gasoline with diesel fuel and maintaining a higher top speed and increased range of approximately 160 Km (100 miles) over the original M113. The Dieselization Kit replaces the 209 Hp Chrysler Model 75M gasoline engine of the original M113 with the highly reliable Detroit Diesel 6V53 engine rated at 212 Hp. The package also replaces the transmission, transfer gear case, radiator and alternator with properly sized units.

The technical data package developed for the conversion of the original M113 includes many modifications designed to improve the performance, maintainability, safety, and reliability of the M113A1. These improvements are not related to the dieselization but can easily be installed during the dieselization and rebuild of the vehicle.

The M113A2 conversion packages include improvements in suspension, cooling and personnel heating systems. These changes provide better cross-country mobility, increased cooling efficiency and longer engine life. The purpose of the improvement in suspension is to permit higher cross-country speed and mobility. This improvement in performance is accomplished by increasing the vertical road wheel travel, which decreases the roughness of the ride.

The primary component changes to the suspension are the addition of shock absorbers to the right and left second road wheel stations, use of higher strength torsion bars, and raising the rear idlers two inches. All shock absorbers used in the new system are longer life design. The road wheel arms are also newly designed. In addition, the shock absorbers mounting pins on the road wheel arms are removable and can be replaced without replacing the entire road wheel arm.

Improvements in the cooling system are the result of numerous reports of engine problems attributable to to marginal cooling. To reduce these problems, the cooling system efficiency was increased by relocating the cooling fan and radiator, increasing the radiator capacity and fan speed, and adding a surge tank for more positive deaeration of the coolant. By relocating the fan and radiator, two previous drawbacks of the old system were eliminated. In the new radiator design, the air circulating across the radiator fins is cool outside air rather than heated air from engine compartment components. The radiator is also relocated to prevent clogging by oil and dirt from the engine compartment. The new radiator has an increased capacity, and the new surge tank increases the allowable cooling system drawdown.

One of the spin-offs from the Improved Cooling System (ICS) kit is the Dual-Air Personnel Heater. A characteristic of the ICS is that a slight vacuum is developed within the crew compartment. Under certain conditions, when the vehicle is closed, this vacuum can be great enough to draw exhaust fumes from the old single inlet heater back into the crew compartment. The dual-air inlet heater eliminates this problem by completely separating the combustion gasses from the heated air within the crew compartment. This new heater is applied during production and overhaul concurrently with the Improved Cooling System.

The M113A3 is an improved version of the M113A2. The standard A3 package or RISE (Reliability Improvement of Selected Equipment) package includes an upgraded propulsion system, greatly improved driver controls, external fuel tanks and 200 Amp alternator with 4 batteries. Additional A3 improvements include incorporation of spall suppression liners and provisions for mounting external armor. The external differences between the M113A2 and the M113A3 are the external fuel tanks and provisions for the installation of an add-on armor kit.

The A3 conversion package contains all the components necessary to install the OEM or US Government supplied 6V53T turbocharged engine and X200-4/4 transmission. The new hydrostatic steer transmission permits use of a more powerful 275 HP turbocharged Detroit Diesel 6V53T engine, and eliminates the transfer case and controlled differential. The RISE powertrain package increases fuel economy, acceleration, hill climbing speed and braking capabilities. This allows the vehicle to maintain speed through corners by accelerating the outer track rather than braking the inner track as on the A2. The additional horsepower also allows installation of an external armor kit increasing the gross vehicle weight to 31,000 pounds. This provides mobility comparable to currently fielded vehicles such as the M1 Abrams Main Battle Tank and M2/M3 Bradley Infantry Fighting Vehicles.

Steering is improved with an automotive-type steering yoke and foot brake arrangement which improves driver control, lessens fatigue and simplifies driver training superior to the A1/A2 steering/braking laterals. Due to load matching ability and increased steering capability, cross country performance is also improved.

Crew survivability is increased by the addition of spall suppression liners. The inside of the vehicle (sides, roof and rear) are covered with spall suppression liners which limit troop injuries from the effect of overmatching weapons by restricting the spread of spall if a round penetrates the hull.

External fuel tanks were developed to improve survivability and increase capacity within the M113A1/A2 crew compartment. Replacing the internal tank with two tanks mounted on the sides of the vehicle's rear ramp provides an additional 16 cubic feet of internal space. Placement of the exterior fuel tanks also reduces fire hazard to the crew compartment. The external tanks are bolted to the rear of the vehicle with five bolts. All fuel line connections are located near the tank hull and interface for easy replacement. Two tanks and independent valving provide redundancy in the fuel system allowing continued operation when one tank is damaged. The external fuel tanks increase the vehicle weight by 900 pounds and the length by 17 inches.

A variety of add-on armor kits are available for additional crew protection.

By 2005 about 2,500 of the M113 class military vehicles had come through Anniston to be upgraded since 1994. United Defense in Anniston refurbishes a vehicle a day.

Allison Transmission Division, General Motors Corp., Indianapolis, Ind., was awarded a $16,119,687 modification to firm-fixed-price contract DAAE07-97-C-T476 on February 22, 2001, for 241 transmissions (X200-4A), in support of the M113 Overhaul/Conversion Program. The transmissions will be installed as upgrade components in M113A3 Armored Personnel Carriers, M577A3 Command Post Carriers and M113A3 based Opposing Forces Surrogate Vehicles. Work will be performed in Indianapolis, Ind., and is expected to be completed by Dec. 31, 2001. Allison Transmission, Indianapolis, Ind., was awarded on Jan. 21, 2004, a $7,743,466 modification to a firm-fixed-price contract for 92 X200-4A transmissions for the M113 family of vehicles. Work will be performed in Indianapolis, Ind., and is expected to be completed by Nov. 30, 2004. Contract funds will not expire at the end of the current fiscal year. This was a sole-source contract initiated on March 12, 2003. The U.S. Army Tank-Automotive and Armaments Command, Warren, Mich., is the contracting activity (DAAE07-03-C-N079).

Allison Transmission used FY2004 funds to install new transmissions on older M113 Armored Personnel Carriers. This work ensured that American troops have reliable, working armored equipment to keep them safe while serving their tour of duty. The funding came in addition to a $67 million contract with the Army that Senator Bayh secured in February 2004 for Allison to produce transmissions for the Abrams M1A2 Battle Tank and the M113 Armored Personnel Carrier.



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