Humvee History

For many readers of Military Vehicle Magazine, owning an historic military vehicle (HMV) is a hobby. While a hobby doesn’t have to have a practical purpose, when it comes to vehicular hobbies you should probably consider some practicalities in regard choosing a vehicle… most importantly how much the vehicle is going to cost in time and money versus how much enjoyment it brings. There is zero practicality in buying a vehicle that’s too large, too small, or otherwise unsuited to whatever you plan to do with it, or a vehicle that requires more maintenance and operating expenses than you’re willing or able to give it.

With large numbers of HMMWVs being released from U.S. military service, you may be considering the purchase of one, so the purpose of this three-part article is to drop a little knowledge that might help you decide if you really want a HMMWV and are willing and able to give it the time and attention and money it requires. We’ll start with some HMMWV history; and it may be worth noting that while HMMWVs were sometimes called “Hummers” by GIs early in their service years, today that term is generally used for the civilian H1, H2, and H3 versions, while the common military nickname is “Humvee.”

Backtracking, World War II could be described as vehicular war, a war in which ground mobility—transporting troops and supplies quickly and efficiently — proved to be a major factor in winning battles and ultimate Allied victory: indeed, General Dwight D. Eisenhower said, “The equipment most vital to our success in Africa and Europe was the bulldozer, the jeep, the 2-1/2 ton truck, and the C-47 airplane. Curiously, none of these were designed for combat.”

It should be noted that three of these pieces of vital equipment were vehicles.

After WWII, the U.S. military set about developing a new fleet of standardized tactical vehicles, commonly called the M-series, retaining the 1/4-ton jeep in the incarnation of the M38 and M38A1, the 3/4-ton truck as the M37, and the 2-1/2-ton truck as the M35 and M211, but dropping 4- and 7-ton trucks in favor of 5- and 10-ton vehicles. It’s a mystery, though, why 1-1/2-ton trucks were phased out, because this left a significant transport gap between 3/4-ton and 2-1/2-ton vehicles. The 1-1/2-ton trucks, most notably the Chevrolet G-506, had certainly proved their usefulness during WWII, but perhaps it was thought that the 3/4-ton M37 pulling its 3/4-ton M101 trailer could bridge that gap. This concept works on paper but not always in practice, because cargo loads can’t always be split 50/50. The military did attempt to fill this gap a little more effectively in the late 1960s with the M715 1-1/4-ton truck and the 1-1/2-ton M561 Gama Goat, but both vehicles were problematic, especially the Goat. During the 1970s, various CUCVs (Commercial Utility and Cargo Vehicles), such as the Dodge M880, in the 1-1/4 ton range were utilized, while the role of 1/4-ton truck was performed by the M151 MUTT. (Military Utility Tactical Truck)

In the late 1970s, the U.S. military drew up specifications for a high mobility multipurpose wheeled vehicle (HMMWV) to replace all tactical vehicles in the 1/4- to 1-1/4-ton range — the M151, M715, and M561, as well as some CUCVs — with one vehicle. The requirements included high ground clearance, low silhouette, superior mobility, and speed, both on highway as well as in tactical field operations. Several companies submitted initial proposals, but only three, General Dynamics, Teledyne, and AM General—the latter already building M151s and M35 2-1/2 ton trucks—were interested enough to actually submit prototypes. Teledyne’s prototype was based on an existing vehicle, the Cheetah. while AM General started from scratch on the drawing board and delivered its prototypes for testing in April 1982. These vehicles proved satisfactory, and AM General was awarded a contract for development of several more prototypes. The original M998 HMMWVs had an unladen weight of 5,200 pounds with a payload of 2,250 pounds. They were fitted with a 6.2 liter V-8 General Motors diesel engine and a three-speed GM automatic transmission. After rigorous testing, AM General was awarded a production contract in 1983, which called for 55,000 vehicles to be delivered within a five-year period.

The first HMMWs were configured as six basic types or variants: Cargo-Troop Carrier, Armament Carrier, TOW Missile Carrier, Ambulance, Shelter Carrier, and Prime Mover. Based on these first models, more than 20 variants were then developed, many of which differed from one-another in only minor ways. For example, there were seven variants of Cargo/Troop Carrier and eight variants of Armament Carrier. Since HMMWV production began, many new variants have been developed, while others were discontinued. The HMMWV was, indeed, able to effectively replace some vehicles in the U.S. military’s tactical fleet, such as the Dodge M880 and other CUCVs, and the M561 Gama Goat, but due to its size the HMMWV proved less viable trying to play the role of the much smaller M151… a problem that was always apparent but became glaringly obvious in Afghanistan where the HMMWV was too large to traverse some mountain roads and village streets.

As forementioned, the first HMMWVs were fitted with a 6.2-liter G.M. V-8 diesel engine — the same used in many GMC Suburbans—with a rated net horsepower of 150 and a gross horsepower rating of 165 at 3600 rpm. Current models use the GM 6.5 liter engine, which produces 160 net hp at 3400 rpm. A 25 gallon fuel tank provides an operating range of around 250 miles.

The first production HMMWVs were equipped with a 3-speed GM automatic transmission, while newer units have a GM 4-speed. All HMMWVs have automatics: the vehicle was designed to be simple to operate, and an automatic transmission gives the driver one less thing to think about under combat conditions. It also makes it easier for a wounded soldier to drive the vehicle, as well as minimizing training time for young GI’s of the current generations who never learned how to drive a stick.

The HMMWV’s body tub, rear fenders, and tailgate are made from heat-treated aircraft-quality aluminum, with the panels bonded and then riveted together. The hood is hinged at the front to swing up and away from the windshield, and is made from a composite of fiberglass and plastic. The HMMWV’s off-road capabilities are enhanced by 16 inches of ground clearance with outboard-mounted geared axle hubs, full-time four-wheel-drive and independent suspension, plus steep approach and departure angles. HMMWVs have a 60 percent slope climbing ability, and can operate on 40 percent side hills. They possess a normal 2.5 foot water-fording capability which is increasable to 60 inches when equipped with a fording kit, though despite a few myths in the civilian world, HMMWVs are not amphibious. HMMWVs may be fitted with a Central Tire Inflation System (CTIS), which, as on the WWII DUKW, allows the driver to inflate or deflate the tires from inside the cab for better flotation or traction depending upon the terrain. HMMWVs may be fitted with a Warn Mil-12000 winch. HMMWVs had an advantage over other vehicles in the U.S, Military’s tactical fleet -- that of being a multipurpose platform (though to a lesser degree the same could be said for vehicles such as the M37 and M35). Beginning with the first six types, many improvements were made, and the basic model was upgraded to the M998A1 and then M998A2. HMMWVs were soon available in 15 different configurations, yet all shared the same engine, chassis and transmission, along with many other interchangeable parts. This meant fewer training hours for motor-pool mechanics, as well as simplified supply and maintenance. In other words, a HMMWV is basically one set of major components for many different vehicles.

Current model HMMWVs, M998A2 or M1097A2, were initially called “Heavy Humvees” because they weigh about 700 pounds more than earlier units. An HMMWV can accelerate from 0-30 (yes, 30) mph in about 8 seconds. Fuel consumption is approximately 10-11 mpg at 55-60 mph. Safe top speed is about 70 mph. though the engine is usually governed to keep the speed around 60, and in some cases 55 mph.

Though having full-time four-wheel-drive, a HMMWV spends most of the time with its center differential unlocked. This permits the axle differentials to divide the torque and keep the wheels from spinning in slippery situations. Even on more extreme terrain, the center differential may still be left unlocked. When the going really gets rough, the driver can lock the center differential... though HMMWVs have some problems climbing steep slopes in loose dirt or sand. All major power-train components are mounted above the frame and protected by skid plates.

There are over 20 variants of HMMWVs presently in service with the U.S. Military, including cargo/troop carriers, weapons platforms, ambulances (four litter patients or eight ambulatory patients), M220 TOW missile carriers, M119 howitzer prime movers, M1097 Avenger Pedestal Mounted Stinger platforms, MRQ-12 direct air support vehicles, S250 shelter carriers, and other roles. Primary models include:

M56 Coyote Smoke Generator Carrier, M707 Knight M966 TOW missile, Armored M996 Mini-Ambulance, Armored M997 Maxi-Ambulance, Armored M998 Cargo/Troop Carrier, M998 Avenger M 1025 Armament Carrier, Armored M1026 Armament Carrier, M1035 Soft-Top Ambulance, M1036 TOW Missile, Armored with winch, M1037 Shelter Carrier, M1038 Cargo/Troop Carrier with winch, MI042 Shelter Carrier with winch, M1043 Armament Carrier, Up-Armored M 1044 Armament Carrier, Up-Armored with winch, M1045 TOW Missile Up-Armored, M1046 TOW Missile Up-Armored Armored with winch, M1069 Tractor for M119 105-mm Gun, M1097 Heavy, M1097 Heavy Avenger, M 1109 Up-Armored Armament Carrier.

Three HMMWVs can be carried in a C-130 Hercules, six in a C-141B Star-Lifter, and fifteen in a C-5A Galaxy. Two HMMWVs can be slung from a CH-47 Chinook or a CH-53 helicopter, while one may be slung from a UH-60A Blackhawk. HMMWVs can be also be delivered by Low Altitude Parachute Extraction without the aircraft having to land. HMMWVs may be fitted with a wide range of weaponry, including 7.62 mm and 50 caliber machine guns, an MK 19 40 mm grenade launcher, or a TOW missile system. Armor kits include the Armor Survivability Kit (ASK), and the FRAG 5 and FRAG 6. The ASK adds about 1000 pounds to the weight of the vehicle. The Marine Armor Kit (MAK) offers more protection but increases the weight even more. The FRAG 6 kit not only adds more than 1000 pounds but also increases the HMMWVs width by 2 feet. The heavy doors require a mechanical assist to be opened and closed. Additionally, during an accident or attack, the armored doors may jam shut, trapping the occupants inside. The doors of some Up-Armored HMMWVs are fitted with outside hooks or loops so they can be pulled off by another vehicle. Vehicle Emergency Escape (VEE) windows were also developed.

Driving a HMMWV may be disappointing because it’s rather like cruising around in a 1-1/2-ton dually pickup with the entire vehicle being the width of the duals (add two more feet if Up-Armored) with sound-effects similar to the engine compartment of a Greyhound bus. Additionally, unlike driving most large vehicles such as an M35 or even a G-506, you will not sit high above most other traffic for good visibility.

As should be apparent by now, and like most vehicles, HMMWVs have their share of limitations, problems and quirks. As already mentioned, one problem is simply the size, which can make it difficult or impossible to drive off-road where smaller vehicles can go. Someone considering a purchase may want to pace off an approximate space of 15 by 7.5 feet in their shop, garage or driveway... add another two feet to the width if pondering an Up-Armored variant. Being much more high-tech than most vintage HMVs, a HMMWV’s mechanical or electrical problems can be difficult to diagnose and repair in a home workshop or out in the field. Replacement parts are not cheap, though parts availably continues to increase. Like MUTT parts, HMMWV parts will probably be available for many years into the future simply because there are so many. As with most newer vehicles, a HMMWV has relatively few lubrication points compared to HMVs such as the M37 or M35; instead it uses replaceable bushings and fittings in its suspension and steering system. The key word is “replaceable.” This is not a vehicle that one simply greases at regular intervals and its chassis lasts indefinitely. Components such as control arm ball joints, suspension bushings and steering linkage wear out fast in a unit that is driven daily, and much more so if the vehicle is used off-road. As with any vehicle, worn out suspension bushings will affect wheel alignment, causing irregular wear on the tires… which are also expensive.

If you’re still considering a HMMWV as an HMV, stay tuned: Part Two of this article will cover what to look for when shopping for one.