Why the Humvee is getting replaced by a Chevrolet-Silverado-HD-powered armored truck
After over three decades of faithful service, the United States Army and Marine Corps are replacing the AM General Humvee in frontline service with the Oshkosh JLTV. Although Humvees will continue to serve behind-the-scenes with the Army and Marines until 2050, the new JLTV (short for Joint Light Tactical Vehicle) is as much as a technology leap over the Humvee as the Humvee was to the Jeep-like Ford M151 MUTT before it. With that in mind, here’s how the Humvee and JLTV stack up on paper.
Under the Hood
When AM General developed the Humvee back in the late ‘70s and early ‘80s, its naturally aspirated 150-hp 6.2-liter diesel V-8 paired with a three-speed automatic was a game-changer compared to the M151 MUTT’s gas-swilling 71-hp 2.3-liter I-4 and four-speed manual. Since the Humvee first went into service, its engine has been upgraded to a 6.5-liter turbodiesel V-8 that produces a scant 190 hp, paired with a four-speed automatic. That’s hardly enough power to motivate the base Humvee’s roughly 6,000-pound (2,721-kg) curb weight, let alone the 13,000-plus-pound (5,900-plus-kg) curb weight of an armored Humvee.
The Oshkosh JLTV’s powertrain represents decades of automotive advancement. In an effort to keep costs in check and hit performance targets, Oshkosh chose GM’s new L5P Duramax 6.6-liter turbodiesel V-8 engine to power the new JLTV. A familiar sight under the hoods of 2017 Chevrolet Silverado HD and 2017 GMC Sierra HD models, the JTLV’s Duramax engine is modified for severe duty and actually detuned to around 400 hp by Gale Banks Engineering for the JLTV. The JLTV’s transmission is also a durable, commercially available component; it’s the Allison six-speed automatic transmission also used by GM heavy-duty pickups.
Where the Rubber Hits the Road
More than anything, both the Humvee and JLTV are designed around their four-wheel-drive systems. Some of the military’s requirements for what would become the Humvee include the ability to climb a 60 percent incline, traverse a 40 percent slope, and ford 2.5 feet of water without a snorkel, or 5 feet with a snorkel. Those requirements dictated a lot of the engineering and design choices AM General made in the Humvee. It was fitted with an independent suspension, its wheels were mounted on portal axles providing gear reduction and boosting ground clearance to 16 inches. The Humvee’s entire drivetrain and even its brakes were sucked up into the body of the vehicle, making the cabin a tight squeeze but ensuring that the Humvee’s off-road ability would meet military requirements. The whole package was rounded out with a full-time four-wheel-drive system with a two-speed transfer case, locking differentials, and a Central Tire Inflation System (CTIS).
Although much of the military’s requirements for the JLTV are still classified, it did want the 14,000-pound (6,350-kg) JLTV to go everywhere the Humvee could go but be faster and with more capability. To that end, Oshkosh fits each JLTV with its TAK-4i suspension system. A fully independent double-wishbone design with electronically adjustable high-pressure gas shocks, Oshkosh tuned the JLTV’s TAK-4i suspension in the Baja 1000, giving this military off-roader some serious Ford F-150 Raptor-rivaling chops. The JLTV’s suspension has 20 inches of wheel travel and the ability to raise and lower the suspension as needed, negating the need for portal axles. Without the optional snorkel kit, and with its suspension in its highest setting, the JLTV can ford 5 feet of water without breaking a sweat. Like the Humvee, the JLTV also has a full-time four-wheel-drive system with low-range, locking differentials, and a CTIS.
Although Humvees were initially pretty reliable in the field, as they aged and as the military upgraded them with heavy armor that increased wear and tear, they became garage queens to many servicemen and women. During the testing phase of the JLTV program, the U.S. Army and Marine Corps brought along 22 up-armored Humvees to test alongside Oshkosh, Lockheed Martin, and AM General’s JLTV entrants, with each manufacturer providing 22 test vehicles. During nearly three years of testing, platoons equipped with Oshkosh JLTVs had the highest levels of mission success.
Oshkosh’s JLTVs were also far and away the most reliable of the bunch, averaging 7,051 miles (11,347 km) between operational mission failure, defined as a system failure that prevents the vehicle from accomplishing its mission. Up-armored Humvees were surprisingly the second-most reliable of the group, averaging 2,968 miles (4,776 km) between failures, followed by the Lockheed Martin JLTV at 1,271 miles (2,045 km) between failures, and the AM General BRV-O JLTV, which averaged 526 miles (846 km) between failures.
Humvees offered up far better protection to its occupants compared to the open air jeeps they replaced. In the same way that AM General improved the light tactical vehicle by adding a roof and doors, Oshkosh does the same by baking a base-level of armor into each JLTV. Utilizing lessons learned on its M-ATV MRAP (Mine-Resistant Ambush Protected vehicle) program, the JLTV features a V-shaped hull to deflect blasts from below, bulletproof windows, and an armored crew capsule. Compared to an up-armored Humvee, a basic JLTV offers multiple orders of magnitude more protection from bullets and bombs to its occupants. Each JLTV is also capable of being fitted with a “B-Kit” of armor, boosting protection to MRAP-levels of protection.
The Oshkosh JLTV is currently in low-rate initial production. Although the U.S. Air Force, Navy, and Coast Guard haven’t revealed any intention of buying the JLTV, the U.S. Army and Marine Corps will begin to field JTLVs to front-line troops by fall of 2018.