THE MARCH TOWARD
Alternative technologies continue to draw interest as push for reduced emissions, fuel efficiency continues
With buzzwords like “green” and “eco-friendly” crop- ping up at every turn, one
might be tempted to believe that the
age of alternatives had arrived. But in
truth, while they are making headway,
the march of things other than internal combustion engine technology
has been neither rapid nor steady.
Judged solely by the PR generated,
it would seem that a greater number
of alternative options would be making their way into more on-highway,
mobile and power generation equipment. The reality, however, is that
alternatives remain a fraction of the
But that’s not to say that they’re
standing still. Every year, alternative
technologies are refined, undergo further testing and next-generation systems go into real-world testing.
The on-highway industry has
seen the bulk of the action as more
fleets of trucks are seriously examining hybrids and hydraulic assist
systems as viable ways to reduce
emissions, save fuel and become a
little “greener” in the process. The
power generation arena has also
seen more activity with fuel cells as
backup power systems in telecommunications applications and auxiliary power units. Even off-road mobile
machinery is getting some serious
consideration (as explained in a story
elsewhere in this issue).
So while they might not be there
yet, it’s clear the march toward the
mainstream continues. With that,
here is a brief overview of some of
the latest developments of suppliers
of alternative technologies.
BOSCH REXROTH CORP.
Mobile Hydraulics Division
2730 Research Dr.
Rochester Hills, MI 48309
Phone: (248) 265-5217
Fax: (248) 844-2698
Bosch Rexroth’s Hydrostatic Regenerative Braking (HRB) system is a
parallel hydraulic hybrid system developed for Class 7 and 8 vehicles. The
system is designed to reduce fuel consumption up to 25% and reduce emissions, while extending brake service life.
The Fairfax County Solid Waste
Program in Virginia is using a Bosch
Rexroth parallel HRB in the county’s
first hydraulic hybrid refuse truck. The
Rexroth HRB system was retrofitted in
January on a 2007 Mack Granite truck
with a Heil Environmental Formula
5000 rear loader body.
According to Bosch Rexroth, the
HRB system can generate up to 25%
savings in fuel and energy costs
depending on duty cycle and driver
behavior. The actual savings for this
project will be determined for the
Fairfax project during field trials.
The HRB system for the refuse truck
incorporates a hydraulic pump/motor
connected to the driveline to capture
energy during vehicle braking. When
the driver presses the brake pedal,
a hydraulic unit integrated into the
drivetrain pushes hydraulic fluid into a
high-pressure reservoir. The resulting
resistance makes the vehicle deceler-
ate. When accelerating, the hydraulic
pressure reservoir is controlled elec-
tronically to release the pressure and
relieve the load on the engine. Each
time a driver brakes, the HRB system
stores energy that would otherwise be
lost, Bosh Rexroth said.
Fairfax County, Virginia’s refuse truck
equipped with Bosch Rexroth’s parallel
hydrostatic regenerative braking system.
In the Fairfax application, it is estimated that a refuse truck starts and
stops approximately 800 times a day
filling trash and recyclables, allowing
energy to be captured during braking
and used when the truck is started
again. This also has the potential to
extend brake wear and reduce brake
maintenance costs associated with
vehicle downtime, the company said.
According to Bosch Rexroth, the
HRB system is ideal for use in various
heavy commercial vehicle applications that undergo frequent starts and
stops. The system can be integrated
and retrofitted in the chassis as an
add-on system, in some cases without major modifications.
Currently the HRB system is installed
on approximately 35 trash collection
and recycling trucks worldwide.
continued on page 72
June 2011 DIESEL PROGRESS NORTH AMERICAN EDITION 71