KEEP THOSE TRANNIES ROLLING
Acura’s SH-AWD System: AWD Performance Leader
I
n previous issues of Keep Those
Trannies Rolling, we introduced
you to some of the all wheel
drive systems offered by Ford, General Motors and Chrysler. In this issue we’re looking across the Pacific to introduce Acura’s SH-AWD system. The Acura SH-AWD system, short
for “Super Handling-All Wheel Drive,” is a fulltime, fully automatic, all-wheel drive, traction and handling control system.
This system was designed and engi-
neered by Honda Motor Company and was first introduced in North America in the second generation 2005 Acura RL. The SH-AWD system has since been added to other Acura models such as the RDX, the MDX, the TL, and for 2010, Acura’s new ZDX. Honda describes the SH-AWD as
a system that “provides cornering per- formance that responds to the driver’s needs and at the same time provides outstanding vehicle stability.” To the regular guy on the street, this means power and performance in an all-wheel drive vehicle, which is something that had been sadly lacking.
What Makes Acura’s
SH-AWD Different?
What makes Acura’s SH-AWD
system so different from the rest of the pack? Acura’s SH-AWD, unlike any other AWD system in the world today, has the ability to control front-to-rear torque distribution and independently control torque distribution to each indi- vidual rear wheel as needed, depending on driving conditions. This ability to control the torque to each individual rear wheel is what makes the SH-AWD
52
Acura MDX SH-AWD
system different from all the rest.
Components of the SH-AWD System
The SH-AWD system consists of a
front wheel drive engine and transmis- sion assembly with a torque transfer unit attached to the side of the trans- mission, a driveshaft, an electronically controlled differential, an acceleration device (on RL models only) and a SH-AWD control module. Let’s take a brief look at each of these components. • Torque Transfer Unit: The
torque transfer unit or transfer case is mounted to the side of the transmission. The transfer unit is purely mechanical; not computer controlled. The purpose of the torque transfer unit is to transfer
torque from the transmission through the driveshaft to the rear differential. • Electronically Controlled
Differential: The electronically con- trolled rear differential (figure 1) con- sists of a conventional hypoid ring and gearset, an acceleration device (on RL models only), and a direct, electromag- netically controlled clutch system. This clutch system consists of a set of coils, planetary gearsets, and electromagneti- cally controlled multiplate clutches. The electronically controlled differen- tial is controlled by the SH-AWD con- trol module, and, unlike any car today, is capable of diverting anywhere from 0%–100% of the driving torque to either rear wheel. • Acceleration Device: The
GEARS May/June 2010
by Pete Huscher
members.atra.com www.atra.com
Acura RL SH-AWD
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