Among the leaders in Serial Hybrid truck application is Oshkosh Truck
Corp., which implemented the design in its new Heavy Expanded Mobility
Tactical Truck (HEMTT) A3 third-generation prototype. HEMTT A3
unveiled in February 2005 was the first production-ready tactical
defense vehicle to feature a diesel-electric drive system known as
ProPulse Hybrid Electric Drive system. The same technology is implemented in the FMTV versions
proposed by Oshkosh for the US Army.
The prototype HEMTT A3 is also equipped with an
enhanced load handling system, an independent suspension and collision
avoidance system. According to Oshkosh, all the technologies used for
the prototype are matured and once approved for production, the
vehicle roll out of the assembly lines is scheduled within two years.
Oshkosh uses a proprietary technology called ProPulse, which uses a
diesel engine to power a large electric generator, which provides
direct power to the wheels, eliminating the torque converter,
automatic transmission, transfer case, and drive shafts. The system
has no batteries, using ultracapacitors for energy storage instead.
Designed for service life of 10 – 20 years, the ultracapacitors are
less sensitive to extreme cold than batteries. A regenerative braking
function stores engine energy and then uses it to assist in the next
braking operation, reducing wear and tear on the brake system.
According to Oshkosh, this mechanism increases fuel economy by up to
20 percent over conventional power trains.
When stationary, the HEMTT A3 becomes a power station,
generating 200 kW of exportable power with the current 450 hp engine.
If uprated to a 505 hp engine, it could generate 400 kW. The vehicle
is 3,000 pounds lighter than its predecessor while maintaining a
13-ton payload capacity and improving reliability through the use of
lightweight, high-strength materials. This allows the new truck to
carry cargo while in transit on a C-130 aircraft, a first for the
HEMTT line. An integral armored cab can field-installed in less than
eight hours allowing commanders to respond to changing threat levels
Several companies are competing for a future Army
program to demonstrate "plug-in" version of the US Army FMTV truck.
BAE Systems built a two-wheel drive hybrid FMTV truck, under contract
to the FMTV manufacturer Stewart and Stevenson back in 1999. BAE also
developed a six-wheel-drive hybrid prototype as part of a technology
demonstration under the FCS program. This truck already demonstrated
improved fuel economy, compared to conventionally driven FMTV truck.
The vehicle can also produce 200 kW of continuous exportable power.
A future replacement for today's military trucks could
be the Future Tactical Truck System (FTTS), Advanced Concept
Technology Demonstration (ACTD) managed by The National Automotive
Center (NAC), which reports to the Army Tank-Automotive and Armaments
Command. NAC is sponsoring demonstrations for light, medium (utility)
and heavy (maneuver sustainment) hybrid-electric trucks and specific
technology developments for motor, generator, and energy storage and
power control technologies.
The British MOD is also looking at the potential
benefits of HED, under a program led by QinetiQ. The British HED 6x6
demonstrator vehicle will incorporate a serial HED system employing
'in-hub' electric drive systems. The QinetiQ team includes Magnetic
Systems Technology, Multidrive and BAE Systems Land Systems (formerly
Vickers Defence Systems).