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HEMTT A4

A recent paper prepared by the Congressional Budget Office (CBO) helped highlight several critical aspects of the U.S. Army's tactical wheeled vehicle fleet. Titled "Replacing and Repairing Equipment Used in Iraq and Afghanistan: The Army's Reset Program," the September 2007 paper stated: "With so many trucks being left in the theater, returning units must rely on equipment supplied from excess stocks or left behind by deploying units. In some cases, as with HMMWVs [Humvees], FMTVs [family of medium tactical vehicles] and heavy expanded-mobilily tactical trucks [HEMTTs], there is no surplus-indeed, the Army does not have enough of those types of trucks to equip all of its units."

Elaborating on that shortage, the CBO paper noted: "Even in the absence of constraints arising from operations in Iraq, the Army would need almost 30,000 additional FMTVs and almost 3,000 more HEMTTs to fully equip its forces." Fortunately, in the case of HEMTTs, the Army will soon begin receiving the initial quantities of new HEMTT A4 platforms, enhanced capability systems that will significantly expand warfighter capabilities on the battlefields of today and tomorrow.

According to Mike Ivy, director, Army Tactical Vehicle Programs, Defense Business, Oshkosh Truck Corporation, the HEMTT A4 is a product improvement to the HEMTT Al. Ivy explained that the new A4 design includes enhancements like a new drivetrain, upgraded suspension system, a new "ready-to-armor" cab, electrical system improvements and installation of a J1939 data bus.

"It's all based off the same HEMTT platform that has been in service since the early 1980s," Ivy said. "But if s a product-improved truck. So it's not a program 'new start' or anything like that. And it will give the Army a significantly improved capability for the coming years."

The vehicles will enter the Army's wheeled fleet through a combination of new production vehicles and remanufactured former A2 models that will be taken down to the frame rails and sent back through the new vehicle production line.

Characterizing the HEMTT A2 now in the field as "the workhorse of Army tactical logistics," Ivy acknowledged that "the A2 is in theater today with an add-on armor kit. And with the add-on armor it has attendant issues on things like suspension and the horsepower necessary to drive the truck, and so on."

With the A4 systems, the horsepower will be increased through the installation of a new 500 hp Caterpillar C-15 engine (peaks at 515 hp to provide 70 hp more than HEMTT A2). Another drivetrain enhancement involves the Allison 4500 SP/five-speed automatic transmission, rated for 600 hp and offering 1,750-pound torque, gross input, to handle more power.

"The Allison-Caterpillar lash-up in the drivetrain is going to be a significant improvement over today's vehicle," Ivy said. "That will compensate for the addition of the armor weight. We're [also] making suspension changes to account for the addition of armor weight. We're installing climate control in the cab-that's something that has to be done in an 'after market' fashion on the old A2-and we're going to do that on the factory floor now, which will make the armor installation a much easier and quicker process.

"So we're doing a number of things that will address-I wouldn't call them problems-but they are issues with the A1, as the A2 has been armored and really run hard in theater today," Ivy added.

According to Ivy, HEMTT A4 origins date back approximately two years, to an Army contract that directed Oshkosh Truck Corporation to product-improve the HEMTT A2. Following an analysis-of-alternatives process, the Army then put the company under contract to design the truck to integrate the new C-15 engine, a greater cooling package and a ready-to-armor cab.

"That began about two years ago, based primarily on customer initiative to modernize the HEMTT A2," Ivy observed. "The HEMTT . …