Not so long ago, the US industry began mass production of the new Oshkosh JLTV multipurpose army vehicles. This technique is intended to replace existing HMMWV machines and is built on the basis of their operating experience. It is expected that the new cars will become a full-fledged replacement for the existing ones, but due to a number of characteristic differences they will be able to more effectively solve the same problems. Naturally, plans to replace one car with another could not but raise the question: which is better, HMMWV or JLTV.
In May last year, the American edition of Motor Trends offered its version of comparing two army vehicles. Although Christian Sibo's article How the Humvee Compares to the New Oshkosh JLTV is not new, it is still relevant and interesting.
The author begins his article with a reminder of current events. After three decades of faithful service, the AM General's HMMWV (High Mobility Multipurpose Wheeled Vehicle) multipurpose vehicle is shifting to a secondary role, giving way to Oshkosh's new JLTV (Joint Light Tactical Vehicle). Humvees will remain in service until the middle of the century, but now they only have to deal with auxiliary tasks. The new JLTV car, which will take on the main role, differs from its predecessor as much as the HMMWV once differed from the M151 MUTT car. With this in mind, the author proposes to compare "on paper" two modern samples.
Under the hood
Initially, at the turn of the seventies and eighties, the AM General HMMWV car was equipped with a 6, 2 liter turbocharged diesel engine of the V8 type and a power of 150 hp. the engine was mated to an automatic three-speed gearbox. Its predecessor, the M151, had a 2.3-liter I4-type 71-horsepower engine coupled to a four-speed manual gearbox. Thus, against the background of the existing car, "Humvee" looked like a real breakthrough.
Having entered the army, the HMMWV underwent modernization and received a new diesel engine with a volume of 6.5 liters with a capacity of 190 hp. A four-speed automatic transmission was now also used. However, even after such an upgrade, the engine power was barely enough to ensure sufficient mobility for a machine weighing 6,000 pounds (about 2,725 kg). After installing the reservation "Humvee" weighed up to 13 thousand pounds (5, 9 tons), which led to known problems.
The new JLTV project used modern ideas and solutions that have appeared in recent decades. Oshkosh chose the General Motors L5P Duramax 6.6 HP V8 engine in an effort to achieve the optimum power / cost ratio. Similar products are used on Chevrolet Silverado HD and GMC Sierra HD vehicles. However, before being installed on an army vehicle, the engine was boosted to 400 hp. Gale Banks Engineering was involved in the project to finalize the engine.
The drivetrain for the JLTV was also selected based on market availability. The machine is equipped with commercial units from Alisson, including a six-speed automatic transmission. Similar devices are used on heavy pickup trucks from General Motors.
When tires meet the road
Both the Humvee and the JLTV are built around an off-road undercarriage. At one time, the future HMMWV was required to climb a slope of 60% and move with a lateral roll of 40%. Fords up to 2.5 feet (750 mm) deep, the car had to overcome without preparation, and with an air supply pipe, cross water bodies twice as deep. These requirements led to the formation of a number of characteristic features of the appearance of the HMMWV.
The car from AM General received an independent suspension based on two portal axles. Due to this, the clearance was brought to 16 inches (406 mm). All transmission units, as well as the brakes, were literally pulled into the car body. On the one hand, this worsened the ergonomics of the habitable compartment, but on the other hand, it made it possible to obtain high performance that meets the customer's requirements. The chassis and transmission included four wheels with their own gearboxes, locking cross-axle differentials and a centralized wheel inflation system.
K. Seibo reminds that a significant part of the technical requirements for the JLTV car is still secret. At the same time, it is known that the customer wanted to get a car weighing 14 thousand pounds (6350 kg) with mobility at the Humvee level. At the same time, she must overcome the same routes and obstacles faster and with a large load. To solve this problem, Oshkosh used the TAK-4i type independent suspension. Each wheel is mounted using a pair of wishbones and an electronically controlled air shock absorber.
The JLTV suspension provides 20 inches (508 mm) of wheel travel, while the controllable dampers allow for variable ride height. As a result, the vehicle no longer needs portal bridges. With no additional air tube and maximum suspension lift, the machine can cross a ford 5 feet deep. Like its predecessor, the JLTV also features lockable cross-axle differentials and an inflating system.
Reliability
Initially, Humvees were very reliable machines and coped with their tasks. However, later, the cars, which were already of considerable age and had exhausted part of the resource, received an additional reservation, which was distinguished by its great weight. The increased load led to increased wear. As a result, many cars moved to the Garage Queen category - most of the time they stood idle in garages and rarely participated in certain operations.
As part of the JLTV program, US Army and Marine Corps specialists conducted comparative tests of several new and existing vehicles. They were attended by HMMWVs with additional armor, as well as prototypes from Oshkosh, Lockheed Martin and AM General. 22 cars of each type entered the tracks. Tests lasted almost three years, and during this time prototypes from Oshkosh JLTV showed the best reliability.
In terms of reliability, Oshkosh cars outpaced all competitors by a wide margin, according to published data. Between serious breakdowns, which did not allow the continuation of the task, such cars on average managed to go 7051 miles - almost 11,350 km. Surprisingly, the overweight armored Humvees were the second most reliable, breaking after 2996 miles (4820 km) of track. The Lockheed Martin JLTV averaged 1,271 miles (2,045 km) between failures, compared to only 526 miles (846 km) for the AM General car.
Armor
The old jeeps, which were replaced by the HMMWV, had no protection whatsoever; their crew and passengers were literally in the open air. The new "Humvee" received full-size sides and a roof, which provided protection, at least from bad weather. Similar changes can be observed when replacing the HMMWV with newer JLTVs. In the design of the new machine, some measures are initially used to protect the crew and internal units from certain threats.
Oshkosh drew on its experience with the M-ATV MRAP program to build a new multipurpose vehicle accordingly. JLTV is equipped with an armored capsule compartment for the crew and passengers. All glazing of the car is made bulletproof. The bottom of the capsule body has a V-shaped cross-section, which allows the shock wave of the explosion to be diverted to the sides.
The basic Oshkosh JLTV outperforms the Humvee with attachment armor in terms of head protection. At the same time, its creators have provided for the possibility of using additional protection. A set of hinged panels called the B-Kit brings the level of protection of the machine to the level of modern models of the MRAP class.
At the time the Motor Trends article appeared, Oshkosh was assembling new cars in limited quantities prior to full production. The air force, naval forces, and the coast guard, which have HMMWV vehicles on supply, were not yet going to replace them with new JLTVs. At the same time, the army and the ILC have already placed large orders for new equipment. According to last year's plans, the operation of the Oshkosh JLTV in the first line units was to begin in the fall of 2018.
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The article "How the Humvee Compares to the New Oshkosh JLTV" was published over a year ago, but is still relevant today. It is mainly devoted to technical issues, and data on production and operation, which have already become outdated in some way, do not occupy a significant place in it.
In general, the results of a comparison of two multipurpose vehicles, created by order of the US Army, with a difference of several decades, could be easily predicted. Obviously, the HMMWV and JLTV machines share not only many years of production and operation, but also experience, technology, etc. Based on the experience gained during the operation of the Humvee in peacetime and in conditions of local conflicts, the customer was able to draw up a new technical task. It took into account both the strengths and weaknesses of the existing equipment, as well as the new wishes of the military.
The fulfillment of such a technical assignment was associated with certain difficulties. Among other things, this is confirmed by the results of comparative tests, during which most of the JLTV variants showed insufficient reliability. At the same time, the project from the Oshkosh company turned out to be successful and was able to reach mass production.
In all major respects, the new JLTV multipurpose vehicle outperforms its predecessor. This is not surprising, since such a result was envisaged from the very beginning, already at the start of the program. It is obvious that the operation of a large number of new vehicles will have a positive effect on the capabilities of the army.
Currently, Oshkosh continues the Low Rate Initial Production stage, which provides for the production of equipment in a small series. In the foreseeable future, the serial production of cars will pick up the pace required to fulfill the existing contracts. At the same time, next fall, as previously planned, serial JLTVs will go to serve in hot spots, where they will have to replace armored Humvees, which do not fully meet the requirements of the time.
The contract currently in progress provides for the supply of 16,901 JLTV vehicles in various versions and configurations. There are also preliminary agreements on the further production of equipment. The US Army wants to receive more than 49 thousand new vehicles. Over 9 thousand will go to the Marine Corps. Not so long ago, the first contract was signed by the Air Force, which wants to receive almost 3,300 JLTVs.
The Oshkosh JLTV multipurpose vehicle has already attracted the interest of potential buyers from third countries. Currently, negotiations are underway on a possible supply of equipment to the armies of Great Britain and Lithuania. Several other states have shown interest in the American machine, but are not yet negotiating.
For several decades of service, HMMWV multi-purpose vehicles have become obsolete morally and physically, as a result of which they no longer meet the current requirements for the technology used at the forefront. To replace them in this role, a new sample was created, which has obvious advantages. For the foreseeable future, Oshkosh JLTVs will have to take the place of Humvees, which will now be used in secondary roles. Obviously, this had to happen sooner or later, and it seems that the replacement for the outdated technology came out very successful.
