THE FOUR-WHEEL DRIVE SYSTEM XWD - Gmeuropearchive.info

Electronically controlled
limited slip differential (eLSD)
XWD controls the torque distribution not
only between the two axles (front and rear),
but also between the two rear wheels.
It is the job of the Electronically Controlled
Limited Slip Differential (eLSD), an electronically
controlled hydraulic multiplate clutch
with the effect of a locking differential. It is
fully integrated into the XWD control system
and in normal driving can send up to
40 percent of the torque to the wheel that
has the most grip – in extreme situations
even more.
Three questions
for…
…Paer Johansson,
Group Leader, Design &
Release AWD/PTU-system,
GM Powertrain Europe
Question: What maximum torque can be
transmitted from the XWD four-wheel system?
Johansson: The XWD system is designed for
torque up to 2700 Nm to the rear wheels.
Question: How is XWD controlled?
Johansson: The ECU attached into the Rear
Drive Module (RDM) is fully integrated in the
vehicle CAN. XWD uses all the information
available on board, for example from the
sensors of the ESP system or from the engine
and transmission control units, to enable it
to distribute the force intelligently to all four
wheels.
Question: What is in your opinion the biggest
advantage of XWD?
Johansson: It provides excellent traction and
handling, and makes the vehicle fun to drive.
At the same time the vehicle is secure and
safe.
GM Powertrain Europe
Strada Pianezza 289
I - 10151 Torino
Tel: + 39 011 424 8010
www.media.gmeurope.com 05/08
TECH
GM Powertrain Europe
SHOW TORINO 2008
Handling and traction
The new Cross-Wheel Drive system (XWD)
raises the bar in the auto industry. The intelligent
integrated system is extremely fast
to react and thus gives the driver plenty of
feedback and reassuring security.
Key facts:
THE FOUR-WHEEL
DRIVE SYSTEM XWD
The XWD debuted in the 2008 Saab 9-3
The system thinks in advance: For example,
XWD is activated at the start, before
the front wheels can spin.
XWD divides the drive force not only between
the front and rear axles, but also
between the two rear wheels.
Flexible torque distribution of up to 100
percent between the front and rear axles
Dynamic handling that does not patronize
the driver but effectively supports him
Optional electronically controlled limited
slip differential (eLSD)

THE FOUR-WHEEL DRIVE COMPONENTS
Power take-off
unit passes power
to the propshaft
Propshaft passes power down to the
torque transfer device at the rear.
The rear drive module
with integrated eLSD
manages the torque delivered
to the rear axle between
left and right wheel.
The Torque Transfer Device
modulates the torque between
the front and rear axles.