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Guide>Nissan>2003>Murano>Technology
Highlights (AWD and CVT)
Murano All-Wheel Drive
The Murano's AWD operates in front-wheel drive until wheel slip is
detected. It will then send the appropriate amount of power to the rear
axle as needed. No driver input is required. The AWD system in
"Auto-mode" operates from a 100% front-wheel drive condition to a
50% front 50% rear power split, or any variation in-between based on
vehicle needs and road conditions.A transfer gearbox near the front differential turns a driveshaft to
the rear axle. This driveshaft is always turning when the vehicle is
moving even though power may not be needed at the rear axle.An electronically-controlled multi-plate clutch pack is mounted in
the rear differential housing to direct power to the rear axle.
An "AWD-LOCK" switch will give a fixed 50/50 power distribution
front to rear at speeds of approximately 19 miles per hour (30kph) and
below. When speeds rise above 19 mph, the AWD Controller will determine
power distribution front to rear based on vehicle needs and road
conditions. When speeds drop to 19 mph and below the fixed 50/50 condition
will resume. According to Nissan, AWD LOCK is intended for low-speed, low traction conditions
only.
The AWD Drive Coupling contains two clutches:
The control clutch is triggered by an electric magnet that receive
signals from the AWD Controller. The control clutch operates a ball
bearing cam mechanism that determines the amount of pressure to the main
clutch assembly. The main clutch assembly transfers power to the rear axle according
to the pressure of the control clutch. Full pressure (clutches locked)
gives a 50/50 power split. Less pressure varies the power transfer to the
rear axle.
Xtronic CVT
While automatic or manual transmissions use multiple gear sets with an integral clutch and bands to achieve separate gear ratios, the Xtronic CVT replaces those discrete gear ratios with an infinitely adjustable ratio design.
Instead of using fixed gears, Xtronic CVT transmits power through two variable diameter pulleys and a high-strength steel belt. The Xtronic CVT "changes" ratios smoothly and seamlessly with no perceptible pauses, jerks or lurches - virtually eliminating traditional shift shock.
During acceleration, the pulleys move in opposite directions and the steel belt rides on a smaller diameter, closer to the axis; when the pulleys are close, the steel belt rides on a larger diameter, near the outer rim. The pulleys are controlled to expand and contract in opposite directions so the ratio of the drive diameters between the two pulleys can be varied over a wide range, resulting in an infinitely variable drive ratio. The Xtronic CVT offers a spread of "gear" ratios between its lowest and highest range (2.371:1 to 0.439:1).
At the heart of the Xtronic CVT is a high-strength steel belt, which is as strong as steel, but as flexible as a belt. The strength enables it to handle a high amount of torque input, fitting for Murano's
V-6 engine.
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