Mercedes-Benz 2010 GL350 BlueTEC Automobile User Manual


 
and rear axle differential to improve vehicle
traction.
The center differential compensates for
differences in wheel rotation between the
front and rear axle.
The rear axle differential compensates
differences between the rear wheels.
i
At the front axles, the 4-ETS system
compensates for any traction problems.
For more information on off-road driving, see
“Off-road driving” (Y page 262).
A few words about differentials and
differential locks
When a vehicle negotiates a turn, wheels on
the outside of the curve must travel farther
and rotate faster than the inside wheels. The
differential, the operation of a set of gears
that allows the powered wheels in a vehicle
to turn at different speeds, makes this
essential function possible.
The drawback is that the differential also
sends most of the engine’s power to the
wheel with the least load or strain on it. For
example, if one of a vehicle’s powered wheels
sits on a patch of snow and spins because
there is no traction, all of the engine’s power
will go to that wheel because the power will
take the path of least resistance. Meanwhile,
the opposite wheel, sitting on dry pavement
where it could get enough grip to start the
vehicle moving, sits idle because it receives
no power.
The 4-ETS addresses this problem and
provides for good control and steering ability
by automatically slowing the slipping wheel
and thus increasing the power to the other
non-slipping drive wheels to get the vehicle
moving. The ESP
®
and the 4-ETS in this
vehicle feature such intelligent limited-slip
differential technology, ideally suited for on-
road and light off-road driving. Transfer case
position LOW (Y page 120) also enhances off-
road driving capabilities.
More extreme off-road conditions may call for
another solution, engaging a differential lock
or preventing the differential from operating
altogether. This vehicle comes with two
differential locks: transfer case (center) and
rear. Each can be engaged simply by
operating the rotary switch located on the
center console (Y page 123). When the
transfer case (center) differential is locked,
the combined (or average) speed of the front
wheels is identical to the combined rear
wheel speed. When the rear differential is
locked, both rear wheels turn at the same
speed, independent of the individual torque.
Please be aware that engaging the differential
locks will significantly reduce the steering
ability of the vehicle.
For your safety and the safety of others and
to prevent damage to the vehicle, the
differential locks must not be engaged when
driving on paved roads. It is important to
understand that during on-road/paved
driving, differentials are absolutely necessary
for providing the essential control and
steering ability of the vehicle. The differential
locks, therefore, must not be engaged when
driving on paved roads and should only be
used to the extent necessary to negotiate off-
road conditions which cannot be handled by
the systems (the 4-ETS, the ESP
®
, and the
transfer case in LOW RANGE mode) this
vehicle comes equipped with.
Switching differential locks
!
If the differential locks are engaged,
accelerate gently when setting the vehicle
in motion.
Only operate the vehicle on a single axle
dynamometer if the axle not being driven is
jacked up or the associated propeller shaft
is disconnected.
Otherwise the transmission could be
damaged.
122
Differential locks
Controls in detail
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