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M915 Truck Family

The M915 is almost a carbon copy of the commercial tractor-trailer truck and weighs 14 tons. In 1999, the M915 FOV Integrated Products Team (IPT) began the M915 Line Haul Extended Service Program to upgrade 800+ late-1970's vintage M915A0 truck tractors in the Army inventory to what became the M915A4 truck tractor.

On 18 September 2000 fielding of M915A4s to ARNG began at Camp Dodge, Johnston, IA. These were the first of the M915s operated within the ARNG to be upgraded under the glider program. The program addressed the primary maintenance cost drivers and reasons for non-mission capable readiness: corrosion, electrical, and transmission.

Assembling an M915A4 simply involved removing the engine, bogy, and pintle from a donor M915 and installing these serviceable components on a glider. A glider is typically a truck without a drive train and rear axle/suspension assembly (or "bogy"). Gliders are being acquired under a multi-year contract with Freightliner, Inc. With this concept the Army was able to upgrade the M915 at about one-half the cost of a completely new truck.

The all new M915A4 glider includes an air conditioned cab mounted on a frame with front axle, wheels and tires, muffler, radiator, fifth wheel, Allison automatic transmission, and front-rear axle hubs (with ABS components installed). It needed only the retained components to be installed to make the M915A4 truck tractor.

Assembly was based on using serviceable donor components with an acceptable remaining service life. Most of the Cummins NTC400 Big Cam I engines in the M915 fleet were known to have reasonably low miles and had performed well over the years. A healthy engine will put out the necessary horsepower.

To assess the engine's health and bring the engine up to the necessary standards for use in the M915A4, an inspection checklist was created. Checklists were also created for the bogy, batteries, and pintle.

The original concept for the M915 Upgrade included retention of the rear wheels and tires. In 2000, the program implemented the Army's Chief of Staff policy directive to phase out dangerous split rims. All bogy wheels and tires were replaced with standard commercial wheels and 11X22.5 radial tires. This eliminated a dangerous and potentially lethal hazard. Converting to newer technology radial tires simplified the inventory process and provided for greater durability, mileage, and fuel economy.

The M915A4 Glider Kit program is a US Army Reserve Command (USARC)-directed conversion of M915 line-haul trucks to a more modern version of the equipment. M915A4 Glider Kit line-haul tractors are assembled at Fort McCoy as part of a US Army Reserve Command-directed program. The program takes usable parts, such as the engine and rear axle, from an M915 line-haul tractor and combines them with an upgraded cab, electronics, automatic transmission, new chassis, front axle, tires and antilock brake systems on the M915A4 Glider Kits. The program saves the government about 50 percent of the cost of a new vehicle and gets the equipment into the hands of units quicker than purchasing a new vehicle.

Army reservists in the maintenance field prepare, rebuild and/or transfer usable equipment, such as rebuilt engines and rear axles, to a new chassis through the Operation Platinum Wrench (OPW) program. The line-haul trucks have up-to-date steering, suspension and braking systems. The time required to complete each conversion depends on the expertise of the soldiers working on the equipment and the number of soldiers working on each vehicle. The soldiers must remove and rebuild engines and rear axles, as necessary, from the old M915 line-haul trucks and install them on the upgraded Glider Kits.

The full implementation of the M915 to M915A4 upgrade program also involves addressing the early 1980's technology diesel engine. While a healthy Cummins Big Cam I engine will still provide the necessary power that the M915 normally mission requires, it is an outmoded mechanical type engine. The original concept for the M915 upgrade program suggested identifying and introducing a modern electronic engine as an available substitute engine under the MTS technical insertion technique. Freightliner engineers determined that installation of an electronic engine into an existing M915A4 would be both impractical if not impossible for field installation and uneconomical.

A second option emerged from a TACOM sponsored OSCR project to develop a quasi-electronic engine from the Cummins Big Cam III engine. The engine developed from the project would become available to M915A4 owning units as an alternative to the existing Cummins Big Cam I engine for installation during either the M915 to M915A4 upgrade process or when the M915A4 engine requires replacement at some point following the vehicle upgrade. This MTS option can improve accuracy of diagnostics; improve maintenance turn around time; enable interface with emerging digitization" initiatives, such as Movement Tracking System and "telemaintenance; enhance training; add engine prognostics capabilities; and enable capturing historical operational data for vehicle performance and fleet management.

Configure the 1980's technology Cummins Big Cam III mechanical remanufactured engine with sensors, wiring harness, and electronic control unit (ECU) to develop a electronic-like engine. The complete CENSE engine would be available as kit with all hardware that would be necessary for installation, installation instructions, and software. A M915A4 equipped with a CENSE engine will allow the user to access historical and real-time operational data and conduct electronic engine diagnostics using a Windows compatible program running on a PC/laptop/SPORT.

Under an OSCR project the M915 FOV IPT is working in partnership with AM General, Cummins Engine, USAR, and Freightliner. Cummins developed a prototype CENSE engine using a remanufactured Big Cam III engine. Cummins was able to utilize the CENSE concept and software that is already in use on heavy trucks used in mining operations. This engine has been installed in a M915 glider kit owned by the U. S. Army Reserves. The installation procedures are being developed and necessary glider configuration changes are being identified. The CENSE engine hardware will then be provisioned with supporting technical documentation. Projected availability of a CENSE engine is mid-2001. Possible future phases may include integration of CENSE software with the planned development of the M915A4 IETM, and development kits for field installation onto a Big Cam III and Big Cam I engine.

A second initiative ongoing in conjunction with the CENSE engine project is identification of a replacement bogy configuration to also help bring the M915A4 up to 21st century standards. Modernizing the bogy will reduce sustainment costs, address all the worn components not replaced during the upgrade, improve ride quality, and enable changing the configuration of the HD4560P transmission to a 5 speed. A better match of the axles with the rest of the drive train would improve fuel economy and enhance performance.



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