tow PORSCHE CAYNNE 2013 2.G Information Manual
[x] Cancel search | Manufacturer: PORSCHE, Model Year: 2013, Model line: CAYENNE, Model: PORSCHE CAYENNE 2013 2.GPages: 79, PDF Size: 14.97 MB
Page 8 of 79

The Cayenne | Cayenne · 16
15 · The Cayenne | Cayenne
Everything has changed.
Apart from the concept.
Cayenne.
At Porsche, we are continually changing.
Looking for a new and different approach.
Without ever losing sight of where we’ve
come from. That ’s how we remain true to
ourselves.
The basic Cayenne concept is therefore
the same. We’ve just continued to
improve it: the Cayenne is now lighter –
up to 165 kg
1) depending on the specifi -
cation – and also more dynamic, more
comfortable, and closer to the road than
ever before. Without detracting from the
qualities required for off-road driving or
towing heav y loads.
Its naturally aspirated 3.6-litre V6 engine
features direct fuel injection (DFI, p. 40),
variable valve timing on both inlet and
exhaust, and a variable resonance intake manifold – for a generous output and
excellent fuel economy. In other words:
we have enhanced the performance,
while significantly lowering the weight,
fuel consumption and CO
2 emissions. The
figures speak for themselves: maximum
torque of 400 Nm, 220 kW (300 hp),
a top speed of 230 km/ h and the abilit y
to accelerate from 0 to 100 km/ h in
7.5 seconds. With both fuel consumption
and CO
2 emissions reduced by 20 %.1)
Delivering this power to the road effi -
ciently, Porsche Traction Management
(PTM, p. 47) combines active all-wheel
drive with an electronically variable multi-
plate clutch, automatic brake differential
(ABD, p. 47) and anti-slip regulation (ASR,
p. 47). Together they enable the perfect
distri bution of drive torque to all four wheels, whether on long straights,
through tight corners or on surfaces with
different
friction coefficients – for dynamic
handling
and increased traction. Drive is
trans mitted through a high-performance
six-speed manual gearbox (p. 44), which
ensures optimum progression through
the gears.
In addition to the standard 18-inch
Cayenne wheels and larger brakes, the
Cayenne can be fit ted with the optional
Porsche Ceramic Composite Brake
(PCCB, p. 66) – for even more outstand -
ing brake performance.
Another key advantage: a total weight
saving of approximately 50 % compared
with equivalent cast-iron discs. The generous standard equipment
includes partial-leather seats, climate
control, the CDR audio system with
touchscreen, cruise control and auto
-
matic headlight activation. For added
comfort, there’s also a ‘Welcome Home’
lighting function. When you arrive at a
destination after dark, the headlights
remain illuminated for a user-defined
period, lighting your path from the car.
So, a unique blend of the great sports
performance and unrestricted everyday
practicalit y that is t ypical of Porsche.
Let ’s be honest, would you have expected
anything else?
For fuel consumption, CO
2 emissions and efficiency class data, please refer to pages 150/151.1) Compared to previous model.
Page 10 of 79

19 · The Cayenne | Cayenne S The Cayenne | Cayenne S · 20
Power, precision and the potential for more.
Cayenne S.
The Porsche ‘S’ has long been a mark
of heightened sports performance and
abundant reserves of power. On the
Cayenne S, it also stands for strength,
agility and efficiency.
At the heart of the car is a naturally aspir -
ated
4.8-litre V8 engine featuring direct
fuel injection (DFI, p. 40), VarioCam Plus
(p. 39) and a t wo -stage intake manifold.
This helps to reduce fuel consumption
and emissions
1), while ensuring maximum
output. In short: 294 kW (400 hp), max -
imum torque of 500 Nm and a top speed
of 258 km/ h. The Cayenne S accelerates
from 0 to 100 km/ h in as lit tle as 5.9 sec-
onds. Fuel consumption has been reduced
by up to 23 % and CO2 emissions by as
much as 26 %.1) The weight of the car
has also been lowered by 180 kg.
1)
Drive is transmit ted to the road with
smoothness and precision by the
standard eight-speed Tiptronic S, which
includes gearshift controls on the
steering wheel. The result: optimum
use of the available power reserves.
Of course, to apply exceptional power
like this effectively, it needs to be
harnessed and controlled. For example,
by Porsche Traction Management (PTM,
p. 47). On the Cayenne S, this active
all-wheel drive system features an
electronically variable, map-controlled
multi-plate clutch, an automatic brake differential (ABD) and anti-slip
regulation
(ASR). Working in conjunction with ad-
vanced Porsche Stability Management
(PSM, p. 68), PTM ensures the required
torque split in every driving scenario. On
or off road. During performance driving,
as well as on leisurely journeys or when
towing heav y loads.
The design also reflects the impressive
power within. The black slats on the air
intakes make them appear larger, and
the car wider. Other distinctive features
include the 18-inch Cayenne S III wheels.
The Porsche ‘S’. A mark to which the
Cayenne S holds true.
For fuel consumption, CO
2 emissions and efficiency class data, please refer to pages 150/151.1) Compared to previous model.
Page 21 of 79

Drive systems and chassis | Engine technology · 42
41 · Drive systems and chassis | Engine technology
Compression with precision.
Essential for getting right to the point.
Direct fuel injection (DFI).
DFI injects fuel directly into the combus -
tion chamber at up to 120 bar with milli -
second precision using electromagnetic
injectors. The injector position and spray
geometry have been carefully designed
to improve output, torque, fuel economy
and emissions. The swirling of the fuel as
it enters each chamber increases the
mixing of air and fuel, thereby enhancing
combustion. By forming the air/fuel mix -
ture directly in the combustion chamber,
DFI contributes to engine cooling. As a
result, it was possible to increase the
compression ratio and therefore power
and efficiency.
Direct fuel injection on the diesel
engine (common-rail injection system).
On the Cayenne Diesel, direct fuel injec -
tion comes courtesy of a common-rail
injection system. The injection pressure
is now up to 2,000 bar, ensuring optimum
distribution of the air/fuel mixture – for
greater performance. The piezoelectric
injectors provide flexible injection rate
adjustment, using exactly metered
quantities of fuel, with multiple injections
for each power stroke to deliver smooth
combustion.
Cooling systems.
A high-performance engine can only
maintain its maximum capability over
a long service life if all components are
operating consistently within a specific
temperature range. The engines in the
Cayenne models are therefore designed
for efficient cooling.
In order to reduce the frictional losses
that occur during warm-up, all Cayenne
models feature comprehensive thermal
management. Using intelligent control,
it activates the different cooling circuits
individually and on demand, thereby
ensuring that the optimum operating
temperature for the engine and trans -
mission is reached more quickly. This
minimises friction – and keeps fuel
consumption and CO
2 emissions low.
The V8 engines have an enhanced coolant
management system offering effective
temperature control throughout the engine.
While 20 % of coolant flows longitudinally
through the crankcase, the remaining 80 %
serves the cylinder heads using the proven
cross-flow principle (from hot to cold).
On all Cayenne models, the piston heads
are cooled using oil-spray jets integrated
within the main lubrication system.
The entire cooling system is designed for
prolonged heav y-dut y use, e.g. off-road
driving or heav y towing and carrying
applications.
Lubrication.
The V8 engines use dry-sump lubrication
to ensure a consistent supply of oil in
all load conditions, especially in off-road
terrain. The oil reservoir is located inside
the engine. This saves on space and
reduces weight.
Oil is circulated around the V8 engines
using a demand-driven pump. This has
been designed for the toughest driving
scenarios on and off road, including per -
formance driving and extreme gradients.
The V6 engines have a wet-sump lubrica -
tion system. Ensuring a reliable supply of
oil, whatever the driving conditions.
For fuel consumption, CO
2 emissions and efficiency class data, please refer to pages 150/151.
Page 23 of 79

Drive systems and chassis | Transmission · 46
45 · Drive systems and chassis | Transmission
Precision control.
Whatever your choice of terrain.
Transmission.
Six-speed manual gearbox.
The six-speed manual gearbox on the
Cayenne has been specifically adapted
for the demands of high-performance
use. The gear lever throw is short and
precise, and each of the six ratios has
been selected for optimum progression
through the gears. As the centre console
rises to meet the dashboard, the gear
lever is close to hand – for an even more
engaging drive.
The standard upshift display in the
instrument cluster helps to reduce fuel
consumption further still. Eight-speed Tiptronic S is also available
as an option on the Cayenne in conjunc
-
tion with the auto start/stop function.
Standard on the Cayenne.
Eight-speed Tiptronic S.
The outstanding feature of the eight-
speed Tiptronic S is a particularly wide
ratio spread. 1st gear is designed for
optimum acceleration when pulling away
and greater performance when tackling
ascents and towing loads in off-road
terrain. Top speed is reached in 6th gear
(in 7th gear on the Cayenne Diesel). The
remaining upper gears are used to lower
the revs at high speed, thereby enhanc -
ing fuel economy and occupant comfort. On the motorway in particular, driving
at low revs will significantly reduce the
noise level inside the vehicle.
In automatic mode, the driver can influ -
ence gearshifts on the Tiptronic S using
the throt tle and brakes alone. Tiptronic S
automatically adapts the gearshift points
for performance driving – equally, if a
more defensive driving st yle is detected,
the system selects a gearshift point that
offers maximum fuel economy. Under
heav y braking, Tiptronic S shifts down to
maximise engine braking.
An electric pump is used to maintain the
required pressure of the transmission fluid,
e.g. to transmit high levels of torque
at
lower engine speeds. The standard sports steering wheel in
conjunction with Tiptronic S has two
ergonomic switches for manual gear
changes. One press forward with the
thumb and Tiptronic S shifts up. One
pull backwards with the index finger and
Tiptronic S shifts down. Either the right
or left-hand switch can be used. The
result: an even more dynamic response
when changing gear.
Standard on the Cayenne Diesel,
Cayenne S, Cayenne S Hybrid,
Cayenne GTS and Cayenne Turbo.
Optional for the Cayenne.
Tiptronic S gear selector
For fuel consumption, CO2 emissions and efficiency class data, please refer to pages
15 0/ 151.
Page 26 of 79

Drive systems and chassis | Off-road capability · 52
51 · Drive systems and chassis | Off-road capability
From urban jungle to the windy wilds.
The Cayenne is perfectly at home on any terrain.
Off-road capability.
Steep ascents leading to snow- covered
mountain lodges, boggy ground or
muddy, loose surfaces – all situations
that the Cayenne handles superbly with
intelligent all-wheel drive. The drive
systems featured on the Cayenne models
deliver exceptional torque. For plent y of
power on tap. On any terrain.
Operating concept.
With the help of Porsche Traction
Management (PTM), the Cayenne can
cope with even the most demanding
off-road scenarios. Simply move the
main off-road control on the centre
console forward or backward to select
one of up to three off-road modes
(depending on the model). Available
on the Cayenne, Cayenne Diesel,
Cayenne S, Cayenne GTS and Cayenne
Turbo, this
function readies the car for
off-road use or reverts the set ting to
normal road driving.
In Off-road Mode 1, for example, the
maps for all relevant systems, e.g. ABS,
are adapted to provide optimum traction.
In addition, High Level I is selected
on vehicles featuring air suspension
with PASM. If that ’s not enough, the air
suspension can be raised further to
High Level II to increase the approach/
departure angle and wading depth.
1)
Push the off-road control forward again
on the Cayenne, Cayenne S, Cayenne GTS
and Cayenne Turbo to activate Off-road
Mode 2 – for even greater traction on difficult terrain, the multi-plate clutch can
be fully locked.
The electronically variable rear diffe
r-
ential on the optional Porsche Torque
Vectoring Plus (PT V Plus, p. 56) is inte -
grated within the all-wheel drive system.
This automatically ensures the optimum
distribution of drive torque on particular -
ly uneven surfaces. If one of the rear
wheels begins to slip, the rear differential
varies the amount of torque transmit ted
through each drive shaft, thereby restor -
ing traction. In Off-road Mode 3, the rear
differential can be manually locked using
the main off-road control. Then both
rear wheels receive the same amount of
torque, regardless of surface conditions.
The optional PDCC (p. 55) enables greater wheel articulation in all three
modes, improving traction still further.
For effective prevention of damage to the
underside of the car, all Cayenne models
can be equipped with optional off-road
underbody protection comprising rock
rails with integrated skid plates, a
reinforced engine-bay guard, additional
protection for fuel tank and rear axle,
and a second towing lug.
1) The Cayenne GTS has a steel -spring spor ts suspension with a 24 mm reduction in ride height (20 mm reduction with optional air suspension). This will lead to restricted capabilit y when driving of f road.
Main off-road control
Page 27 of 79

Drive systems and chassis | Chassis · 54
53 · Drive systems and chassis | Chassis
Shedding weight.
Adding agility, economy and comfort.
Chassis.
Weight reduction.
The axle concept on the Cayenne models
features consistent lightweight con -
struc
tion. The results: enhanced driving
dynamics, lower fuel consumption and
optimum occupant comfort.
Front axle.
The chassis on the Cayenne models
offers a direct response – for a more
rewarding driving experience. The wish -
bones on the subframe-mounted front
suspension with high-mounted upper
arms are in aluminium. This axle design
ensures accurate wheel location, greater
agility and minimal interference on uneven
surfaces. The subframe is secured on
large rubber mountings that reduce road
noise to a minimum.
It is also specially constructed to increase
stability. For enhanced comfort and even
greater active and passive safet y. In the
event of an impact, the subframe deforms
in a predefined manner.
Rear axle.
The rear axle features multi-link suspen -
sion. Ideal for performance road and track
use, it also copes well with the extremely
high towing and carrying loads that are
possible with each Cayenne. The suspen -
sion struts are angled to allow longer
suspension travel and create a deeper and
wider cargo area. As well as providing
additional space, the car is also easier
to
load.
The rear axle design minimises dive and
squat under acceleration and braking.
It also improves mid-corner stability and
compensates for sudden load transfer. In short: it enables a more relaxed
way of driving. Examples of intelligent
lightweight construction on the rear
axle include hollow drive shafts.
Steering.
The steering system has been com pletely
revised and adapted for a more immediate
response and greater driving dynamics.
Around the straight-ahead pos ition, in
particular, the ratio is now more direct.
With the variable steering ratio and spe -
cial valve settings on the power-steering
system, optimum manoeuvrability is
ensured. The turning circle of the Cayenne
models is just 11.9 metres.
The steering column itself consists of
multiple collapsing sections linked by two
universal joints and a special deformation
element provides additional safet y in the
event of a front impact. Electro -hydraulic power steering is
used for the first time on the Cayenne S
Hybrid. The demand-driven pump only
provides assistance to the steering as
and when required, thereby contributing
to overall efficiency.
Power steering Plus.
Power steering Plus is a speed-sensitive
power-steering system.
At higher speeds, the steering becomes
firmer, inputs are more precise and
driver comfort is enhanced. At lower
speeds, it enables easy manoeuvrability
and parking.
Standard on the Cayenne S Hybrid.
Optional for all other Cayenne models.
For fuel consumption, CO2 emissions and efficiency class data, please refer to pages 150/151.
Page 29 of 79

Drive systems and chassis | Chassis · 58
57 · Drive systems and chassis | Chassis
Making headway without getting in a spin.
An approach we thoroughly support.
Porsche Torque Vectoring Plus
(PTV Plus).
A system for enhancing driving dynamics
and stability, PTV Plus offers variable
distribution of engine torque to the rear
wheels and electronically controlled rear
differential. Depending on the steering
angle, steering speed, throttle pedal
position, yaw velocit y and vehicle speed,
PT V Plus optimises steering response
and precision by applying brake pres -
sure to the left or right rear wheel, as
r equired. Specifically, this means that when enter
-
ing a corner at high speed, moderate
brake pressure is applied to the inside
rear wheel. This transfers drive torque to
the outside rear wheel which supports
the steering motion of the car, thereby
improving its cornering dynamics.
At slow and medium speeds, PT V Plus
considerably enhances agility and steer -
ing precision. At high speeds, during
fast cornering and under wheel spin, the
electronically controlled rear differential
ensures additional stabilit y. Also on
variable-grip surfaces, in the wet and on snow, PT V Plus – combined with Porsche
Traction Management (PTM, p. 47) and Porsche Stabilit y Management (PSM, p. 68)
– provides a major contribution to active
safety.
In off-road terrain, PT V Plus reduces
wheel spin on the rear wheels – even when towing heav y trailer loads. The
electronically controlled rear differential
can be fully locked using the off-road
control on the centre console.
Optional for the Cayenne, Cayenne S,
Cayenne GTS and Cayenne Turbo.
Porsche Active Suspension
Management (PASM).
PASM is an electronic damping control
system. It offers continuous adjustment
of individual damping forces based on
current road conditions and driving st yle.
During performance driving or heav y off-
road use, there is an increased tendency
for the body to sway. PASM prevents
this from happening, thereby improving
stability and occupant comfort. PASM
has three setup modes: ‘Comfort ’,
‘Normal’ and ‘Sport’.
Porsche Torque Vectoring Plus (PTV Plus)
Whichever one you select, the system
uses a series of sensors to monitor the
movement of the body. It also gathers
data on lateral acceleration, steering
angle, brake pressure and engine torque
and modifies the damping force on each
individual wheel in accordance with the
selected mode.
PASM remains active at all times. It
automatically adapts to the prevailing
driving conditions, enabling greater
car control and improving comfort and
safety.The Cayenne GTS is the only model in the
range to feature a steel-spring suspension
with a 24 mm reduction in ride height
including PASM. For a lower centre of
gravit y and even closer contact with the
road.
Optional for the Cayenne, Cayenne
Diesel, Cayenne S, Cayenne S Hybrid.
Standard on the Cayenne GTS.
Standard on the Cayenne Turbo:
air suspension with PASM.
Page 32 of 79

Safety and environment | Safet y · 64
63 · Safety and environment | Safet y
Driving with foresight.
Quite literally.
Active safety.
It’s always a pleasure taking corners
in a Porsche. Especially when they’re
now so visible at night. The striking
lighting arrangement is also instantly
recognisable.
Automatic headlight activation.
The headlights are automatically
switched on when darkness sets in
or when driving through a tunnel in the
daytime. Other features include an auto -
matic switch-off and ‘Welcome Home’
function – when you arrive at a destin -
ation after dark, the headlights remain
illuminated for a user-defined period,
lighting your path from the car.
Standard on all Cayenne models.
Halogen main headlights.
The projector-beam halogen main head -
lights feature automatic static range
control and reflection high-beam lights –
for optimum illumination of the road.
Standard on the Cayenne, Cayenne
Diesel, Cayenne S and Cayenne S
Hybrid.
Bi-Xenon main headlights with
Porsche Dynamic Light System (PDLS).
The Bi-Xenon main headlights – which
also have a black surround on the
Cayenne GTS – feature halogen auxiliary
headlights, integrated headlight cleaning
and automatic dynamic range control.
This provides more uniform illumination
of the road in both dipped and high-beam
mode. The dynamic cornering light function
swivels the main headlights towards the
inside of a bend based on the current
steering angle and road speed. The static
cornering lights activate the auxiliary
headlights in order to illuminate more of
the road in tight bends and turns.
PDLS also features speed-sensitive
headlight control and an adverse
weather function, which is activated
in conjunction with the rear foglight –
for even greater safet y, not just at night
and during cornering.
Standard on the Cayenne GTS and
Cayenne Turbo. Optional for all other
Cayenne models.
Porsche Dynamic Light System Plus
(PDLS Plus).
PDLS Plus offers t wo additional func -
tions: high Beam Assistant recognises
oncoming vehicles and automatically
switches the headlights from high beam
to dipped beam.
As you approach a crossing, Intersection
Assistant activates the left and right
indicators, making the beam of light
broader and shorter. This improves illu -
mination of the area directly surrounding
the vehicle, making the driver more
aware of what ’s going on around him.
Optional for all Cayenne models.
Daytime running lights.
Fit ted as standard on all Cayenne
models: LED day time running lights. On the Cayenne, Cayenne Diesel,
Cayenne S and Cayenne S Hybrid, these
are arranged horizontally in the front light
units, whereas on the Cayenne GTS and
the Cayenne Turbo each main
headlight
unit has four LED spotlights. Day time
running lights improve safet y in the
day time as they make you more visible
to other road users.
Taillights.
LED technology is used for all functions
on the rear light modules. For an ultra-
fast response and greater luminance.
In
short: for greater safet y. In an emer -
gency stop, the adaptive LED brake
lights on the Cayenne models pulsate
to alert the traffic behind more quickly
to a critical situation. The high-level third
brake light is integrated into the roof
s p o i l e r.
Headlight on Cayenne Turbo
Headlight on Cayenne, Cayenne Diesel,
Cayenne S, Cayenne S Hybrid
Headlight on Cayenne GTS
Page 47 of 79

1)
Suitable for receiving analogue and digital T V signals
(DVB -T in MPEG -2 standard) where available.
T V tuner
Comfort and transport | Comfor t ·
94
93 · Comfort and transport | Comfor t
TV tuner.
The optional T V tuner receives unen -
crypted analogue and digital television
signals.
1) For your safet y, these can only
be viewed via the PCM display when the
vehicle is stationary. In conjunction with
the Porsche Rear Seat Entertainment
package, T V broadcasts can be received
on the rear screens while the car is in
motion.
Optional for all Cayenne models.
Telephone module.
This optional quad-band GSM telephone
module combines ease of use with
optimised sound quality. Simply insert
your mobile phone SIM card in the slot
in PCM to make calls via the hands-free
facility or optional Bluetooth
® handset.
For even greater convenience, you can
use a Bluetooth
® SIM Access Profile
(SAP)-compatible handset. Once connect -
ed, the GSM antenna on the mobile
phone is disabled to prolong battery
life and the external vehicle antenna
is utilised instead. Depending on the
phone model, you can access contact
details on the mobile phone SIM card
and internal memory and perform all
operations via PCM, voice control or
the multifunction steering wheel, which
means your phone can remain in your
pocket. In addition, the telephone module
enables you to establish a Bluetooth
®
connection to a mobile phone that only
supports the Hands-Free Profile (HFP).
In this case, the GSM connection to
the mobile phone network is via the
handset antenna. PCM acts as a hands-
free system.
A cordless handset with keypad and
display is also available as an option.
This is stowed in the centre console.
However, the handset cannot be used
to establish a Bluetooth
® connection
using the Hands-Free Profile (HFP).
Optional for all Cayenne models.
Voice control.
Do you wish to get to the point – or your
required destination – more quickly? All
you have to do is say so. The optional
voice control system with whole-word
recognition is at your command – without
the tedious task of voice learning. This
means that the voice control system can
recognise the input of an entire address
for a navigational destination, telephone
book entries or radio station names.
Audio prompts make voice inputs even
simpler. You can also browse through
lists by voice command.
Optional for all Cayenne models.
Mobile phone preparation.
With this optional preparation, you can
establish a Bluetooth
® connection with
a mobile phone that only supports the
Hands-Free Profile (HFP) and use the
CDR or CDR Plus audio system, or PCM
as a hands-free system. As a Bluetooth
®-
based solution, you can connect your
handset without even taking it out of your
pocket. The basic phone functions are
accessible via the audio system head
unit. Connection to the mobile phone net -
work is via the handset antenna.
Optional for all Cayenne models.
Universal audio interface.
On vehicles with the CDR audio system,
this optional package located in the front
centre console provides an AUX-In port,
e.g. for a compatible MP3 player. On
vehicles equipped with PCM, the package
includes an AUX-In port and a USB port
which can be used to connect an iPod
®.
The iPod
® as well as other compatible
MP3 players or memory sticks connect -
ed via USB can be operated using PCM.
When listening to music, the system now
also displays the album cover (cover art).
Using the jukebox function, you can store
and play up to 5,000 MP3 files on the
40GB hard drive integral to PCM.
Optional for all Cayenne models.
Page 59 of 79

Comfort and transport | Tra n s p o rt · 118
Loadspace management system.
This facilit y enables you to partition the
luggage compartment and secure
indi-
vidual objects during transit using a rail
system with sliding telescopic bar, a
fixing belt and four variable lashing eyelets.
A reversible mat protects
against dir t
while securing luggage under braking, etc.
The package also includes a loadspace
partition net which provides additional
safet y when the car is fully laden. The
partition at taches to one of t wo easily
accessible points on the rooflining.
Optional for all Cayenne models.
Towbar systems.
For the largest of loads, you can choose
from t wo towing options: an electrically
deployable towbar system or a manually
detachable towbar. With the electric
system, the ball neck is retracted at the
push of a but ton and concealed beneath
the rear apron. Both options have a
13-pin socket and offer a maximum
braked trailer load of 3,500 kg (2,700 kg
on the Cayenne with manual gearbox)
or an un braked load of 750 kg, with a
maximum noseweight of 140 kg. Both
systems are also available for future
installation. All models have a towbar
preparation as standard.
Optional for all Cayenne models.
117 · Comfort and transport | Tra n s p o rt