2018 VOLVO XC90 TWIN ENGINE wheel torque

DRIVER SUPPORT
* Option/accessory.273
WARNINGWhile the power steering is working at
reduced power, the driver support functions
with steering assistance are not available.
In such a situation, the driver display shows
the
Power steering failure or Power
Steering Assist Temporarily Reduced message, combined with a STEERING
WHEEL symbol.
Changing the level of steering wheel
resistance*
To change the level of steering wheel resistance,
see the description of the INDIVIDUAL option
under "Available drive modes" in the "Drive
modes" section.
On models not equipped with drive mode con-
trols and the INDIVIDUAL option, steering wheel
resistance can instead be set in the center dis-
play's Top view under:
Settings My Car Drive Modes
Steering force
Steering wheel resistance settings cannot be
accessed when turning at speeds above
10 km/h (6 mph).
Related information
•
Drive modes (p. 445)
• Pilot Assist (p. 311) •
Lane Keeping Aid (p. 364)
• Steering assistance at risk of collision
(p. 372)
• Park Assist Pilot* (p. 395) Stability system Roll Stability
Control
The Roll Stability Control (RSC 1
) system helps
minimize the risk of a rollover in the event of e.g.
a sudden evasive maneuver or if the vehicle
begins to skid.
The RSC system monitors the lateral angle at
which the vehicle is leaning and registers any
changes. Using this information, the system cal-
culates the likelihood of a rollover. If there is an
imminent risk of a rollover, Electronic Stability
Control is activated, engine torque is reduced and
brakes are applied to one or more of the wheels
until the vehicle has regained stability.
WARNING The vehicle

||STARTING AND DRIVING
* Option/accessory.
438
Related information
• Rear Collision Warning (p. 347)
• BLIS* (p. 348)
• Brake functions (p. 429) Transmission
The transmission is part of the vehicle's driveline
(power transmission) between the engine and
the drive wheels. The function of the transmis-
sion is to change gears depending on speed
and power needs.
The vehicle has an 8-speed automatic transmis-
sion and an electric motor for rear-wheel drive.
The number of gears allows the engine's torque
and power band to be effectively utilized. Two of
the gears are overdrive gears that save fuel when
driving at a constant engine speed. The steering
wheel paddles* can be used to shift up or down
manually. The instrument panel shows the gear
currently in use.
CAUTION Check the operating temperature of the
transmission to help avoid damage to any of
the drive system components. If there is a risk
of overheating, a warning symbol will appear
in the instrument panel and a text message
will be displayed. Follow the recommenda-
tions given.
Symbols in the instrument panelIf a problem should occur with the transmission, a
symbol and a message will appear in the instru-
ment panel. Symbol
Meaning Information and messages related
to the transmission. Follow the rec-
ommendations provided.
Hot or overheated transmission.
Follow the recommendations provi-
ded.
Reduced performance/Acceler-
ation performance reduced
In the event of a temporary fault in
the driveline, the vehicle may go
into a "limp home" mode with
reduced power output to help avoid
damage to the driveline.
Related information
• Gear selector positions for automatic trans-
missions (p. 439)
• Gear indicator* (p. 442)

STARTING AND DRIVING
}}
443
All Wheel Drive (AWD)
All-wheel drive, All Wheel Drive (AWD), also
called four-wheel drive, means that power is dis-
tributed to all four wheels, which improves trac-
tion.
The electric motor that powers the rear wheels
enables electronic all-wheel drive functionality.
To achieve the best traction, power is automati-
cally directed to the wheels that have the best
grip. The system continuously calculates the
need for torque to the rear wheels, and can
immediately redistribute up to half of the engine's
torque to the rear wheels.
All-wheel drive also has a stabilizing effect at
higher speeds. In normal driving conditions, most
of the engine's power is directed to the front
wheels. When the vehicle is stationary, all-wheel
drive is always activated in preparation for maxi-
mum traction during acceleration.
All-wheel drive reacts differently depending on
which drive mode is selected.
Related information
• Drive modes (p. 445)
• Low Speed Control (p. 453)
• Transmission (p. 438) Drive systems
Volvo Twin Engine combines a combustion
engine for the front wheels and an electric motor
for the rear wheels.
Two drive systemsDepending on the selected drive mode and
power available in the electric motor, the drive
systems can either be used separately or in tan-
dem.
The electric motor gets its energy from a hybrid
battery located under the tunnel console. The
hybrid can be charged from a wall outlet or in a
special charging station. The combustion engine
can also charge the hybrid battery using a special
high-voltage generator.
Both the combustion engine and the electric
motor can generate power directly to the wheels.
An advanced control system coordinates both the
drive systems to help optimize driving economy. Hybrid battery - The hybrid battery's function
is to store electrical current. This energy is
provided by plugging the charging cable into
an electrical outlet, through regenerative
braking or from the high-voltage generator.
This provides current to power the electric
motor and to temporarily power the electrical
air conditioning to precondition the passen-
ger compartment.
Combustion engine - The combustion engine
starts when the charge level in the hybrid
battery is too low to provide the power output
requested by the driver.
High-voltage generator
3
- Charges the hybrid
battery. Starter for the combustion engine. 2
This illustration is generic. The layout may vary depending on vehicle m\
odel and software updates.
3 CISG (Crank Integrated Starter Generator) - Combined high-voltage gene\
rator and starter.

||STARTING AND DRIVING
444
Can provide the combustion engine with
extra electrical current.
Electric motor - Powers the vehicle using
electricity. Can provide extra torque and
power during acceleration. Provides electrical
all-wheel drive functionality. Regenerates
braking energy into electrical current.
Related information
•
General information about Twin Engine
(p. 406)
• Starting and stopping the combustion engine
in Twin Engine vehicles (p. 444)
• Drive modes (p. 445)
• Transmission (p. 438)
• Factors affecting electric motor range
(p. 458) Starting and stopping the
combustion engine in Twin Engine
vehicles
An advanced control system determines the dis-
tance that the vehicle can be driven on the com-
bustion engine, electric motor, or both at the
same time. When driving on only the electric
motor, the vehicle may automatically start the
combustion engine due to outside circumstan-
ces, e.g. low ambient temperatures. This is com-
pletely normal. The combustion engine will also
always start when the hybrid battery is nearly
fully discharged.
Climate settings at low temperaturesAt low ambient temperatures, the combustion
engine will sometimes start automatically to help
achieve the desired passenger compartment
temperature and air quality. The amount of time
the combustion engine is running can be affec-
ted by:
• lowering the temperature
• reducing blower speed
• activating Pure drive mode.
Using the electric motor in hot or cold
weather
At very low or high ambient temperatures, the
electric motor's driving range and power may be
reduced and affect how often the combustion
engine automatically starts.
Emission control systemTo help ensure that the emission control system
functions optimally, the combustion engine will
run for several minutes after it is started. The
amount of time the combustion engine needs to
be used varies depending on the temperature of
the three-way catalytic converter.
Related information
• Drive systems (p. 443)
• Economical driving (p. 456)
• Using the electric motor only (p. 457)
• Drive modes (p. 445)

STARTING AND DRIVING
}}
447
OFF ROAD
• Maximizes the vehicle's ability to traverse dif-
ficult terrain or poor roads.
In this mode, ground clearance 4
is high, steering
is light, and all-wheel drive and Hill Descent
Control are activated.
This drive mode is only available at low speeds,
up to 40 km/h (25 mph). If this speed is excee-
ded, Off road mode will be cancelled and AWD
mode will be activated instead.
All-wheel drive requires both the combustion and
electric motor to be in continuous operation,
which results in higher fuel consumption.
In Off road mode, a compass will be displayed
between the speedometer and the tachometer in
the instrument panel. The permissible speed
range will be shown in the speedometer.
This drive mode is optimized for maximum control
when driving at low speeds on very poor roads or
difficult terrain. It raises the chassis 4
, reduces
driveline throttle response, and locks the vehicle
in all-wheel drive. The Hill Descent Control func-
tion facilitates controlled driving on steep down-
grades.NOTE This drive mode is not designed to be used
for normal street driving.
NOTE
Due to the increased ground clearance, if the
OFF ROAD mode was selected when the
engine was switched off, the suspension will
lower when the engine is restarted.
CAUTION
Do not use the OFF ROAD drive mode when
towing a trailer without an electrical connec-
tion. This could result in damage to the pneu-
matic suspension system's bellows.
AWD
•
Improves the vehicle's traction and handling
by increasing all-wheel drive.
This drive mode locks the vehicle in all-wheel
drive. An optimal distribution between front and
rear axle torque helps provide the best possible
control, stability and traction, e.g. on slippery
roads or when towing a heavy trailer or another
vehicle. The AWD drive mode is always available
regardless of the hybrid battery's charge status. Both the combustion engine and the electric
motor are engaged to enable all-wheel drive,
which results in higher fuel consumption.
In the other drive modes, the vehicle automati-
cally adapts the need for all-wheel drive accord-
ing to the road surface, and can activate the elec-
tric motor or start the combustion engine as nee-
ded.
POWER
•
Power mode is designed to provide sportier
driving characteristics and a faster accelera-
tion response.
This drive mode maximizes the combined power
from the combustion engine and the electric
motor by providing power to both the front and
rear wheels. Gear shifting will be faster and more
distinct and the transmission will prioritize gears
with a higher traction force. Steering response is
faster, suspension is stiffer and ground clearance
is lower 4
to help reduce body roll when cornering.
Both the combustion engine and the electric
motor are engaged to enable all-wheel drive,
which results in higher fuel consumption.
This drive mode is optimized for maximum per-
formance and throttle response. It changes the
throttle response, gear shifting program and
turbo boost system. Chassis settings and steer-
ing and brake response are also optimized. The
Power drive mode is always available regardless
of the hybrid battery's charge status. 4
For vehicles with pneumatic suspension.

WHEELS AND TIRES
}}
* Option/accessory. 565
Jack*
The jack can be used to lift the vehicle to e.g.
change a wheel. The illustration is generic – the design may vary.
CAUTION •
When not in use, the jack* should be kept
in its storage compartment under the
cargo compartment floor.
• The jack provided with your vehicle is
intended to be used only in temporary sit-
uations such as changing wheels in the
event of a flat tire. Only the jack that
came with your particular model should
be used to lift the vehicle. If the vehicle
needs to be lifted more frequently or for a
prolonged period, using a garage jack or
hoist is recommended. Always follow this
device's instructions for use. The jack needs to be cranked together to the
correct position in order to fit.
Models with leveling control*
If the vehicle is equipped with the optional pneu-
matic suspension, it must be turned off before
the vehicle is lifted on a jack.
Related information
•
Tool kit (p. 564) Wheel bolts
The wheel bolts hold the wheel in place on the
wheel hub.
CAUTION The wheel bolts should be tightened to
140 Nm (103 ft. lbs.). Over-tightening or
under-tightening could damage the threaded
joints.
Only use rims that have been tested and
approved by Volvo and are included in Volvo's
original product range.
Use a torque wrench to check that the wheel
bolts are tightened correctly.
Do not grease the wheel bolt threads.
WARNING
The wheel bolts may need to be tightened
again several days after a wheel change.
Temperature fluctuations and vibrations can
cause them to loosen slightly.
Locking wheel bolts*A tool for removing the locking wheel bolts is
located in the foam block under the cargo com-
partment floor.

WHEELS AND TIRES
}}
* Option/accessory. 569
1.

Clean the contact surfaces between the
wheel and the wheel hub.
2. Lift the wheel into place. Tighten the wheel bolts securely.
Do not grease the wheel bolt threads.
3. Lower the vehicle so that the wheel cannot rotate.
4. Tighten the wheel bolts in a crisscross pat- tern (as shown in illustration). It is important
that the wheel bolts are securely tightened.
Tighten to a torque of 140 Nm (103 ft.lbs.).
Use a torque wrench to check torque. 5. Press the plastic covers onto the wheel bolts.
WARNING The wheel bolts may need to be tightened
again several days after a wheel change.
Temperature fluctuations and vibrations can
cause them to loosen slightly.
NOTE
•
After inflating a tire, always replace the
valve cap to help prevent valve damage
caused by gravel, dirt, etc.
• Use plastic valve caps only. Metal caps
could corrode and become difficult to
remove.
Related information
•
Leveling control settings* (p. 453)
• When changing wheels (p. 564)
• Hoisting the vehicle (p. 605)
• Jack* (p. 565)
• Tool kit (p. 564)
• Removing a wheel (p. 566) Spare wheel
11
The spare wheel is a Temporary spare and can
be used to temporarily replace a punctured tire
on one of the vehicle's regular wheels. The spare tire is only intended for temporary use.
Replace it with a normal wheel as soon as possi-
ble.
The driving characteristics of the vehicle change
and ground clearance reduces when the spare
wheel is used. Do not wash the vehicle in an
automatic car wash while using the Temporary
Spare.
The recommended tire pressure must be main-
tained regardless of at which position the tempo-
rary spare wheel is used on the vehicle.
If the spare wheel is damaged, a new one can be
purchased from a Volvo retailer.
WARNING Current legislation prohibits the use of the
"Temporary Spare" tire other than as a tem-
porary replacement for a punctured tire. It
must be replaced as soon as possible by a
standard tire. Road holding and handling may
be affected with the "Temporary Spare" in
use. Do not drive faster than 80 km/h
(50 mph).
11
Not available on all models.