Delphi's New Four-Wheel Steering System Featured on GM Concept Truck

13 January 2000

Delphi's New Four-Wheel Steering System Featured on GM Concept Truck at Detroit Auto Show
     QUADRASTEER(TM) by Delphi allows full-size vehicles to maneuver like
                                 compact cars

    DETROIT, Jan. 12 -- Delphi Automotive Systems
announced today that its innovative QUADRASTEER(TM) four-wheel steering system
is featured on General Motor Corp.'s GMC Terradyne concept vehicle.  The
Terradyne debuted here earlier this week at the North American International
Auto Show.
    QUADRASTEER by Delphi is an electronic four-wheel steering system that
enables vehicles to significantly improve handling and maneuverability in
full-size vehicles.
    QUADRASTEER will enable the Terradyne greater ease of maneuverability
while driving at low speeds, provide enhanced stability while trailering, and
offer improved stability, handling and control at higher speeds, especially
while trailering.
    Delphi's unique four-wheel steering system electronically controls the
direction of the rear wheels, helping shorten the turning radius on full-size
vehicles.  The smaller radius allows full-size vehicles to maneuver as adeptly
as compact cars.
    Based on tests with full-size SUVs and pickup trucks, QUADRASTEER by
Delphi reduces the minimum turning circle diameter by an average of 19
percent.  In fact, one full-size pickup's turning radius was reduced from 46.2
feet to 37.4 feet, making it comparable to a Nissan Ultima at 37.4 feet and a
Saturn Coupe at 37.1 feet.
    "The effect that QUADRASTEER has on maneuvering a full-size vehicle is
remarkable," said Paul Tosch, president of Delphi's steering systems division.
"We believe there is going to be a lot of excitement around this technology
when it hits the market, and we are confident it will help our customers
differentiate their products."
    QUADRASTEER will be available in the market early this decade on a program
to be announced.
    QUADRASTEER(TM) by Delphi combines conventional front-wheel steering with
an electrically powered rear-wheel steering system.  The system has four main
components -- a front-wheel position sensor, steerable solid hypoid rear axle,
electric motor-driven actuator, and control unit.  Handwheel position and
vehicle speed sensors continuously report data to the control unit, which in
turn determines the appropriate angle of the rear wheels.  Algorithms are then
used to determine the correct phase of operation.
    The system operates in three principal phases:  negative, neutral, and
positive.  At lower speeds, the rear wheels turn in the opposite direction of
the front wheels.  This is the negative phase.  At moderate speeds, the rear
wheels remain straight or neutral.  At higher speeds, the rear wheels are in
the positive phase, turning in the same direction as the front wheels.
    QUADRASTEER(TM) by Delphi will excite full-size vehicle drivers that
trailer, in particular.  During low-speed, negative-phase towing maneuvers,
the trailer follows the true vehicle path much more closely than with two-
wheel steering.  This makes driving in city traffic with a trailer much
easier, as well as low-speed maneuvering such as backing into a boat launch or
parking a camper at a campsite.  When backing in a trailer, the negative phase
greatly improves the trailer response to steering inputs, making it easier to
put the trailer into position.
    At high speeds, trailering stability is significantly enhanced.  The
positive rear steering reduces the articulation angle between the vehicle and
trailer, which reduces the lateral forces applied to the rear of the vehicle
by the trailer.  This, in turn, reduces the yaw velocity gain and increases
yaw damping of the vehicle and the trailer system.  The net result is
increased trailering stability, reduced trailer sway, and reduced driver
corrective steering to external disturbances such as wind gusts, semi-truck
passing, and road inputs.
    Larry Tomczak, director of engineering at Delphi's steering division,
adds, "QUADRASTEER(TM) by Delphi also enhances high-speed stability when there
is no trailer.  Steering the rear wheels in the same direction as the front
wheels at high speeds reduces the vehicle yaw required to accomplish a
maneuver, thus stabilizing the vehicle response during passing, lane change,
or evasive maneuvers even under adverse road conditions."
    Completely compatible and enhancing to four-wheel-drive systems,
QUADRASTEER(TM) by Delphi can be driver-selective or fully automatic --
depending on the automaker's requirements.  Using a selection panel, for
example, the driver could adjust the performance of the rear-wheel steering
for different driving conditions.  Selections might include one for general
driving, one for trailering, and one for two-wheel steering.  The
QUADRASTEER(TM) by Delphi Systems also provides a controlled return to regular
two-wheel steering if the four-wheel steering system is damaged.
    Delphi Automotive Systems with headquarters in Troy, Mich., USA, is a
world leader in automotive component and systems technology. Delphi's three
business sectors -- Dynamics & Propulsion; Safety, Thermal & Electrical
Architecture; and Electronics & Mobile Communications -- provide comprehensive
product solutions to complex customer needs.  Delphi has approximately 201,000
employees and operates 168 wholly owned manufacturing sites, 38 joint
ventures, 51 customer centers and sales offices, and 27 technical centers in
37 countries.  Regional headquarters are located in Paris, Tokyo, and Sao
Paulo, Brazil.  Delphi can be found on the Internet at
http://www.delphiauto.com .



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