The Victoria Napolitano Bookstore THE DRIVING COMPANY WORKBOOK | Page 11

LOCKERS
When a differential is locked, the wheels
on the same axle can no longer turn at
different RPMs and the same amount
of torque will be present at each wheel.
Differences in traction between the
wheels no longer have an effect because
the wheels must turn at the same RPMs.
Some, but not all vehicles have differ-
ential locks. Do not confuse differential
locks with hub locks! Hub locks secure
the front wheels to the axle when the
vehicle is shifted into 4WD. These are
automatic on most vehicles, but some
still have manually locking hubs. Check
your owner’s manual.
TRACTION CONTROL
Some vehicles have a computerized
system to help with traction. Each
manufacturer has a different name
for it, but they work in the same
manner. The computer will pulse
the brakes on the wheels that are
spinning. Because more torque is re-
quired to overcome the brake pulse
and the differentials are equalizing
the torque, more torque will be pres-
ent at the wheels with traction during
the pulse. This helps get the vehicle
moving again.
FULL-TIME 4WD
A full-time 4WD gives you the best
aspects of 4WD and AWD. When
the vehicle is not in 4WD it is AWD.
Rather than a transfer case link-
ing the front and rear drive shafts,
there is a differential. This allows
the drive shafts to rotate at different
RPMs. You can turn easily because
the sum total of RPMs at the front
axle does not have to equal the sum
total of RPMs of the rear axle. When
the vehicle is shifted into 4WD, this
center differential is locked, mak-
ing it work just like a transfer case
in a 4WD. Full-time 4WD vehicles
have low-range gears.
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