engine AUDI Q7 2009 Owner´s Manual
Page 211 of 426
______________________________________________ A_ d_a ""' p'-- t_iv _ e_ A_ i_r _S_ u_s _,p_ e _ n_s_ i_ o _ n _ ___.9I
- Press the I CARI f unction button . The main menu
Adaptive Air Su spe nsion appears~
page 208, fig. 224 or
~ page 208, fig . 225 .
Select the desired mode by rotating and pressing the
control knob .
Rai sing and l owerin g
If arrow
G) is white :::::, page 208, fig. 225, the vehicle is raised.
If arrow @ is
white, the vehicle is lowered .
The respective arrow stays on until the !eve.I change is complete.
The time used for a level change can vary, depending on the current
driving conditions.
Di sp la yin g th e ve hicle l eve l
The current vehicle level is shown with segments filled out in the
segment display@. If only the bottom segment is filled out, the
vehicle is at highway level. If all segments are filled out, the vehicle
is at high level 2 and has the greatest amount of ground clearance
poss ible.
While the vehic le is being raised or lowered, the target level is indi
cated by an arrow © next to the corresponding segmen t. The arrow
disappears again when the vehic le is at the target level.
Limita tion s to MMI setting s
Please note that not every driving mode can be selected in every
driving si tuation. For example, it is not possib le to switch to "lift"
mode at speeds above 12 mph (20 km/h). This mode is then shown
greyed out in the MMI Display.
The vehicle can on ly be lowered when all of the vehicle's doors are
closed. If one door is open, a ll driving modes whose level setting is
below the current vehicle leve l appear greyed out in the MMI
Display. If a door is opened while the vehicle is being lowered, the
lowering process is interrupted until all doors are closed again .
Contro ls and eq uip
ment
I f the system is temporarily unavailable due to, for instance, an
empty compressed air tank, the driving modes that cannot be se t
appear
greyed out in the MM I Display. As soon as the system is avai l
able again, the driving modes can once more be selected in the
display.
[ i ] Tips
• For additiona l information on the driving modes:::::, page 207,
"Chassis controls".
• When the compressed air tank is empty, the compressor can be
sw itched on by starting the engine. The Adaptive Air Suspension is
once again availab le, after waiting a few minutes. •
Applies to veh icles: with Adapt ive A ir Suspens ion
Appearance in the instrument cluster display
You can view the current vehicle level in the instrument
cluster display.
Fig . 2 26 D ispla y:
A dap tive Air Sus pen-
s ion
~
Vehicle care I I irechnical data
Page 216 of 426
111....__H_ o_ m _ e _L_i _ n _k _® ____________________________________________________ _
Homelink®
Universal remote control
Applies to vehic les: w ith Home link ® universal remote cont ro l
General information
The HomeLink® fe ature can le arn up to th ree r adio
fre quency codes for m ost c urrent transmitters used for
operating garage doors, es tate gates , home or outdoor
ligh ting sy stems, and other devices .
You m ust first pro gram the H omel in k® trans mitter befor e you can
use the system=>
page 215, "Programm ing th e Homelink® trans
m itter".
In order to pro gram t he Homelink® transmitter fo r devices utilizing
ro lling code, a second person on a ladder who can safe ly reach the
ga rage door o pene r m oto r is rec omm ended . It is also necessa ry to
locate the "learn" button on your garage door opener motor. Refer
to t he op era ting instructions for the opene r, as the loca tion and
co lor of this button may vary by manufacturer .
Y ou can still use the o rigina l remote c ontrol fo r th e dev ice at any
time.
& WARNING
• Never use the Homelinkl1JI transmitter with any garage door
opener that does have not the safety stop and reverse feature as
requ ired by federal safety standards . This in cludes any garage
door opener model manufactured before April 1, 1982.
• A garage door opener which cannot detect an object , signaling
the door to stop and reverse does not meet current federal safety
standards . Using a garage door opener without these features
increases risk of serious injury or death .
& WARNING (continued)
• For safety reasons never release the parking brake or start the
engine while anyone is standing in front of the vehicle.
• A garage door or an estate gate may sometimes be set in
motion when the Homelink ® remote control is being
programmed . If the devi ce is repeatedly activated , this can over
strain motor and damage its electrical components -an over
heated motor is a fire hazard!
• To avoid possible injuries or property damage , please always
make absolutely certain that no persons or objects are located
in
the range of motion of any equipment being operated.
[ i ] Tips
• I f you wou ld l ik e mor e infor mation o n Hom elink®, w here to
purchase the Homelink ® compatib le products, or wou ld li k e to
pu rchase the Homeli nk® Home Ligh ting Package, please call t oll
free: 1 -8 0 0 -355 -3515.
• F or Dec lara tion of Compliance to U nite d Sta tes FCC an d Indu stry
C anada regulations=>
page 404 . •
Page 217 of 426
HomeLink® -_______________ ___.
Applies to vehicles: with Homelin k® un iversal remote contro l
Programming the Homelink ® transmitter
The transmitter is programmed in two phases. For rolling
code transmitters, a third phase is also necessary.
111111 111111
-
Fig . 232 Overhead
console : Homelink®
keypad
Fig . 233 Front bumper,
driver side: location of
transmitter unit
Phase 1: programming the overhead keypad
1. Make sure your vehicle is with in operating range of the
remote controlled garage door opener.
2. Set the parking brake=>
& in "General informat ion" on
page 214 .
3. Turn the ignition on . Do not start the engine!
Contro ls and eq uip
ment
4. Press and hold the two outside Homelink® buttons 0
and @for approximately 20 seconds until indicator
light @=> fig. 232 begins to flash. Then release both
buttons. Do not hold the buttons for longer than 30
seconds.
- This procedure only needs to be performed
once . It
erases the factory-set default codes and does not have to
be repeated to program additional remote controls.
5. Press and hold the Homelink® button
0,@ or @ until
the indicator light @starts flashing
slowly. Release the
button.
- The system will remain in programming mode for 5
minutes.
Go to the front of the vehicle and proceed with
phase 2.
Phase 2:
programming the bumper mounted transmitter
6. Hold the original remote control at a distance between 0-
6 in . (0-15 cm) from the bumper below the appropriate
headlight for your vehicle => fig . 233 (use the shortest
distance possible).
7. Aim the remote control just below the driver side head
light.
8. Press and hold the activation button on the remote control.
- May be different in Canada. If so, press and re-press
(cycle) the activation button on your remote control every
two seconds. .,_
Vehicle care I I irechnical data
Page 234 of 426
-Safety belts ----=-----------------
Before driving off
, always:
Fasten your safety belt and make sure you are wearing it
properly.
Make sure that your passengers also buckle up and prop
erly wear their safety belts.
- Protect children with a child restraint sys tem appropriate
for the size and age.
The warning light .ft in the instrument cluster lights up when the
ignition is switched on as a reminder to fasten the safety belts. In
addition, you will hear a warning tone.
After the ignition is switched on, the warning light in the instrument
cluster will a lways come on for about 6 seconds and if the driver has
not fastened the safety belt, a warning tone will also sound for
about 6 seconds. As soon as the driver has fastened the safety belt,
the warning tone will stop and the warning light will go out.
If the driver or front seat passenger have not buckled-up within
about 10 seconds after the warning tone has stopped and the
vehicle is moving faster than about 15 mph, the warning tone will
sound again for about 6 seconds and then stop for 24 seconds and
then repeat this reminder sequence for a maximum of 2 minutes. At
speeds be low 5 mph, the warning tone will not sound .
Fasten your safety belt and make sure that your passengers also
properly put on their safety belts.
& WARNING
• Safety belts are the single most effective means available to
reduce the risk of serious injury and death in automobile acci
dents . For your protection and that of your passengers , always
correctly wear safety belts when the vehicle is moving.
• Failure to pay attention to the warning light that come on,
could lead to personal injury.
a
Why safety belts?
Frontal co11isions and the law of physics
Frontal crashes create very strong forces for people riding
in vehicles.
Fig. 240 Unbelted
occupants in a vehicle
heading for a wall
Fig. 241 The vehicle
crashes into the wall
The physical principles are simple. Both the vehicle and the passen
gers possess energy which varies with vehicle speed and body
we ight . Engineers call this energy "kinetic energy."
T he higher the speed of the vehicle and the greater the vehic le's
we ight, the more energy that has to be "absorbed" in the crash .
Vehicle speed is the most significan t factor . If the speed doubles
from 15 to 30 mph (25 to 50 km /h), the energy increases 4 times! .,
Page 236 of 426
llftl_....::S~a ~f ~e ~ty ~ b~ e~ l~ t ~s ____________________________________________ _
Safety belts protect
People think it's possible to use the hands to brace the
body in a minor collision. It's simply not true!
Fig . 244 Driv er is
cor rec tly r estrai ned in
a su dden b raking
m an euver
Safety belts used properly can make a big difference. Sa fety belts
help to keep passengers in their seats, gradually reduce energy
levels app lied to the body in an accident, and help prevent the
uncontrolled movement that can cause serious injuries. In addition,
safety be lts reduce the danger of being thrown out of the vehic le .
Safety belts attach passengers to the car and give them the benefit
of being s lowed down more gently or "softly" through the "give" in
the safety belts, crush zones and other safety features engineered
into today's vehicles. By "absorbing" the kinetic energy over a longer period of time, the safety belts make the forces on the body
more "tolerable" and less likely to cause injury .
Altho ugh these examples are based on a frontal co llision, safety
belts can a lso substantially reduce the risk of injury in other kinds
of crashes . So, whether you're on a long trip or just going to the
corner store, a lways buckle up and make sure others do, too. Acci
dent statistics show that vehicle occupants properly wearing safety
belts have a lower ris k of being injured and a much better chance of
surviving an accident. Properly using safety belts also greatly
increases the abi lity o f the supplementa l airbags to do their job in a
collision . For th is reason , wearing a safety belt is legally required in
most countries including much of the United States and Canada. Although your Audi is equipped with airbags, you sti
ll have to wear
the safety belts provided . Fron t airbags, for example, are activated
only in some frontal collisions . T he front airbags are not activated in
a ll frontal col lisions, in side and rear collisions, in roll ove rs or in
cases where there is not enough dece leration through impact to the
front of the vehicle . The same goes for the other airbag systems in
your Audi . So, always wear your safety belt and make sure every
body in your vehic le is properly restrained! •
Important safety instructions about safety
belts
Safety belts must always be co rrectly positioned across
t he strongest bones of your body.
Always wear safety belts as illustrated and described in
th is chapter.
Make s ure tha t your safe ty belts ar e always ready for use
and are not damaged .
& WARNING
Not wearing safety belts or w earing them improperl y increase s
the risk of seriou s per sonal injury and death . S afe ty belt s can work
onl y when used corre ctl y.
• Alway s fa sten your s afety belt s correctl y before dri ving off and
make sure all p assenger s ar e correctly restrain ed.
• For m aximum protect ion , safet y belts must always be po si
ti oned properly on the body .
• Never strap more th an one person , includi ng sm all children ,
into any belt.
• Never pla ce a s afety belt ove r a child sitting on your lap .
• Alway s keep feet in t he foot well
in front of the seat while the
vehicle is being driven .
~
Page 290 of 426
llffl __ ln_ t _e_ ll-'"ig ...,_ e_ n_t _t_ e_ c_ h _ n_o _ l_o _,.g= y,_ __________________________________________ _
Intelligent technology
Notice about data recorded by
vehicle control modu les
Your vehicle is not equipped with an Event Data Recorder (EDR),
installed by some manufacturers for the express purpose of
capturing data for retrieval after an accident or crash event . EDR's
are sometimes called "crash recorders" .
Some state laws restrict the retrieva l or downloading of data stored
by EDR's that were insta lled in a vehicle for the express purpose of
retrieving data after an accident or crash event without the owner's
consent.
Although your vehicle is not equipped with an EDR, it is equipped
with a number of electronic control modules for various vehicle systems such as, for example, engine function, emission control, as
well as for the airbags and safety belts.
These electronic control modules also record vehicle-related data during norma l vehicle operation for diagnost ic and repair purposes .
The recording capacity of the electronic control modules is limited
to data (no sound is recorded) and only a small amount of data is
actually recorded over a very limited period of time and stored when
a system fault or other condition is sensed by a control unit. Some
of the data then stored may relate to vehicle speed, direction, braking as well as restraint system use and performance in the
event of a crash or other condition . Stored data can only be read and
down loaded with special equipment .•
Electron ic Stabilizat ion Program (ESP)
General =nformation
The ESP improves the vehicle stability.
Fi g. 2 75 C ente r
co nso le w it h ES P
swi tch
ESP is designed to he lp you maintain vehic le control in situations
where the car approaches the limits of "grip", especia lly when
accelerating and cornering. ESP reduces the risk of skidding and
improves stabil ity under all road conditions .
T he system operates across the entire speed range in combination
with the ABS system. If the Anti-Lock Brake System (ABS) malfunc
tions, the ESP wil l also shut down .
How th e sys te m w ork s
The Anti -Lock Brake System (ABS) , Electronic Differential Lock (EDU
and the Anti-Slip Regulation System (ASR) are integrated in the e lec
tronic stabi lization program . In addition to the data provided by
these functions, the ESP control unit requires additional measure ment data provided by high performance sensors . The rotational
speed of the vehic le about its vertical axis, vehicle acce leration in
the fore-and-aft and lateral directions, the brake pressure and the steering angle are al l measured .
Page 291 of 426
•
The direction in which the driver wishes to travel is determined with
t he aid of the steering angle and vehicle speed and is continua lly
compared with the actual behavior of the vehicle. If the two do not
match, for example, when the vehic le starts hydrop laning on a wet
road, ESP will automatically brake the appropriate whee l to correct
the prob lem.
The vehicle is then stab ilized by the forces acting on the whee l
during braking. If the vehicle is
oversteering (rear tends to skid out
of the turn), the brakes are mainly app lied on the wheel that is on
the outside of the curve. In the case of a vehicle that is
understeering
(tendency to sl ide out of the curve), the brakes are applied as
needed on the wheel that is on the inside of the curve or additionally
on the other wheels . An acoustic signal indicates when ESP brake
application cuts in
~ & .
The system operates across the entire speed range in combination
with the ABS system
~ page 292 . If the Anti-Lock Brake System
(ABS) malfunctions, the ESP will b e out of action as well.
Ac tiva tin g
When you turn on the engine, ESP will automatically be activated
and wil l perform a se lf-tes t. As soon as the test is comp leted, the
system is in norma l operating mode.
Offro ad m ode
ESP should normally be operated in normal mode because this
ensures maximum vehicle stabil ity . If necessary, you can activate
the ESP offroad mode by pressing the button
~ page 288, fig. 275
to obtain maxi mum traction and braking abil ity when dr iving off
paved roads at low speeds . In ESP offroad mode , the ESP indicator
l ight ~
page 19 illuminates and the message E S P Offroad appears
briefly in the display.
The ESP offroad mode can be usefu l in the fo llowing exceptional
s ituat ions when slip or a high ly effective differential locking func
tion is desirable. Examples:
• when driv ing with t ire chains,
• when driving in deep snow or on loose ground,
Inte llig ent tec hn olo gy
• when driving on uneven surfaces with the wheels severely
unloaded (articulation), and
• when rocking the vehicle loose after it has become stuck .
When the unusual situation is pas t, you should shift back to the
normal ESP operating mode by pushing the button again. The
message
ESP /A SR on then appears briefly in the display.
Hill d escent contr ol
The hil l descent control is swi tched on in ESP offroad mode . When
s lowly descending steep gradients on loose ground or when the
ax les are a rticulated, h ill descent control provides assistance by
automatically applying the brakes to keep vehicle speed constant.
The vehicle is also rendered easier to steer by se lective distribution
of braking force . Hi ll descent control intervenes when:
• the accelerator pedal is not pressed,
• the veh ic le is trave lling less than 12 mph (20 km/hl,
• a steep gradient is detected,
• whee l behavior indicates loose ground or conditions with poor
adhesion (e .g . also axle articulation).
Hi ll descent control operates both driving forward and in reverse.
Active hill descent contro l is deactivated by pressing the accelerator
pedal until the conditions for activat ion a lready listed are met again .
& WARNING
• The Elect roni c Sta bil izati on Progr am is ne ve rt hele ss subject to
th e law s of phy sics. It is particul arly important to pay attention to
t hi s fa ct on we t and slippery ro ads . It i s therefore i mpo rtant th at
yo u a lw ays adapt your dri vin g to the condition of the ro ad and
traffi c conditions . Do n ot allo w the in cre ased sa fety provided by
the Elect roni c Stabili zation Progr am system to lull you into
ac cepting additional safety r isks.
• Please be aw are th at in ESP offroad mo de, parti cularl y on a
s m ooth and slippery road , the wheel s m ay have an incr eased •
I t •
Page 292 of 426
--~ln~ t ~e~ ll~ig ;t e~ n~t ...:t~ e::_: c::,: h '..!.'..: n~o ~ l.!::o
3g
:t; yL __________________________________________ _
& WARNING (continued)
tendency to spin and the vehicle may break away -danger of skid
ding!
• Stability is limited in the ESP offroad mode. •
Electronic differential lock (EDL)
The electronic differential lock monitors the rotational
speed of the drive wheels.
General notes
The electronic differential lock (EDU helps the car to start moving,
accelerate and climb a gradient on surfaces providing poor or
almost no grip . Without EDL, this would be difficult, if not impos
sible.
How the system works
The EDL operates automatically. It monitors the rotational speed of
wheels with the help of the ABS sensors=> page 292. If a noticeable
slip is detected at the wheels (e.g. on slippery ground on one side),
the spinning wheels are braked and power is transferred to the
other wheels. This is done up to a speed of about 60 mph (100 km/h).
Noises from the brake system signal that wheel spin is being
controlled.
Driving off
When driving off, always be sure to keep road conditions in mind as
you accelerate. If one drive wheel spins because it is on a surface
with less grip, apply plenty of throttle until the car starts to move.
Overheating of brakes
To prevent the disc brake of the braked wheel from overheating if
subjected to excessive loads on this wheel, the EDL cuts out tempo
rarily. The vehicle remains operational and behaves in the same way
as a vehicle without EDL. As soon as the brake has cooled down, EDL switches on again auto
matically.
& WARNING
• When accelerating on slippery surfaces, such as on ice or snow,
always be careful when depressing the accelerator pedal . Even
with the EDL working, the drive wheels can spin and reduce your ability to control your car. Risk of crash!
• The increased safety afforded by EDL does not mean that you
can take safety risks. Always adapt your driving style to the road
conditions and traffic situation.
[ i] Tips
If a fault occurs in the ABS, the EDL is also not functioning. This is
indicated by the ABS warning light=> page 22. •
Anti-Slip Regulat ion System (ASR)
The Anti-Slip Regulation System prevents the driven
wheels from spinning when the car is accelerating.
General notes
The Anti -Slip Regulation System (ASR) is integrated in the electronic
stabilization program (ESP) . When the vehicle starts up and acceler
ates, the wheels are prevented from spinning by adjusting the
engine power to match the amount of grip available from the road
surface.
How the system works
ASR performs automatically, i.e. without the driver's intervention.
With the aid of the ABS sensors=> page 292, ASR monitors the
speed of the driven wheels. If the wheels start to spin, engine torque
is reduced automatically until the tires find enough grip to lock onto
the road surface. The system is active across the entire speed range . ..,
Page 293 of 426
The ASR works in conjunction with the ABS. If a malfunction should
occur in the ABS, the ASR wil l also be out of action.
& WARNING
The increased safety afforded by ASR does not mean that you can
take safety risks. Always adapt your driving style to the road
conditions and traffic situation.
[ i ] Tips
To ensure that the ASR works properly, all four wheels must be fitted
with identica l tires. Any differences in rolling radius of the tires can
cause the system to reduce engine power when this is not desired.
See also~
page 359, "New tires and rep lacing tires and wheels". •
Braking
General information
What affects braking efficiency?
Operating conditions and driving habits
The brakes on today's automobiles are still subject to wear,
depending large ly on operating conditions and driving habits~& .
On vehicles that are either driven mostly in stop-and-go city traffic
or are driven hard, the brake pads shou ld be checked by your autho
rized Audi dealer more often than specified in the
Warranty & Main
tenance booklet.
Failure to have your brake pads inspected can
result in reduced brake performance.
On steep slopes, you shou ld use the braking effect of the engine .
This way, you prevent unnecessary wear on the brake system. If you
must use your brakes, do not hold the brakes down continuously.
Pump the brakes at intervals.
Controls and equip
ment Safety first Vehicle operation
Intelligent technology
Moisture
or road salt
If you are driving faster than 3 1 mph (50 km/h) and the windshield
wipers are on, the brake pads will briefly touch the brake discs in
regular intervals so as to improve reaction time when braking on
wet surfaces. You, the driver, will not notice anything.
Under certain conditions, for example, when driving through water
or very heavy rain, or even after washing your vehicle, the braking
effect can be reduced due to moisture (or in freezing conditions ice)
on the brake pads. A few careful brake applications sho uld dry off
the brake pads or remove any ice coatings .
The effectiveness of the brakes can be reduced when the vehicle is driven on a salt -covered road and the brakes are not used. Here too,
you should clean off accumulated salt coating from brake discs and
pads with a few carefu l app lications of the brake ~& .
Corrosion
There may be a tendency for dirt to build up on the brake pads and
corrosion to form on the discs if the car is not driven regularly or
only for short trips with litt le use of the brakes.
If the brakes are not used frequently, or if corrosion has formed on
t he discs, it is advisable to clean off the pads and discs by braking
firm ly a few times from a moderately high speed~&.
Faults in the brake system
If you shou ld notice a sudden increase in brake peda l trave l, then
one of the two brake circuits may have failed~& .
Low brake fluid le vel
Malfunctions can occur in the brake system if the brake fluid level is
too low . The brake fluid level is monitored electronically .
Brake lining wear status
Brake lining wear may be checked by visual inspection of the condi
tion of the brake pads through the openings in the wheel. If neces
sary, the wheel may be removed for this inspection
~ page 373,
"Changing a whee l" . ._.
Vehicle care Do-it-yourself service Technical data
Page 294 of 426
___ ln_ t _e_ ll-'"ig ...,_ e_ n_t _t_ e_ c_ h _ n_o _ l_o _,.g= y,_ __________________________________________ _
& WARNING
• You should perform braking maneu vers for the purpose of
cleaning the brake system only if road conditions permit . Other
road u sers mu st not be put at r isk -you may cause an a ccident!
• Before des cending a steep grade, reduce speed and shift trans
mission into a lower gear or lower dr iving range . Do not ride the
brakes or hold the pedal down too long or too often. This could
cause the brake s to get hot and diminish braking effi ciency .
• Do not "ride the brakes " by resting your foot on the pedal when
you do not intend to b rake. This may cause the br ake s to ove rheat ,
premature wear and increased stopping distance.
• Under ce rtain climat ic and operating condit ions such as
passing through water , driving in heavy rain or after washing the
vehi cle , the effectiveness of the brakes can be reduced . In winter ,
ice can a ccumulate on the brake pads , linings , discs and drums .
Carefully apply bra kes fo r a test . Brakes will dry and ice coatings
will be cleaned off after a few careful brake appli cations .
• Driving for an extended period of time on salt -co vered roads
without using your brakes can also affect braking effic iency. Clean
off accumulated salt coating from brake dis cs and pads with a few
c areful brake applications .
• If you damage the front spoile r, or if you install a different
spoiler, be sure the air flow to the front brakes is not ob structed.
Otherw ise the brake sy stem could overheat reducing the effective
ness of the entire brake system .
• Failure of one bra ke cir cuit will impair the braking capability
resulting in an increased stopping distance. Avoid driving the
vehicle and ha ve it towed to the nearest authorized Audi dealer or
qualified workshop . •
Brake booster
T he b rake boost er ad ds extra b ra kin g powe r.
The brake booster works with vacuum pressure which is created
o nly w he n t he e ngine is ru nnin g=> & .
& WARNING
• Never let the vehicle roll to a stop with the engine shut off.
• If the brake booster is not working, for example when towing
your vehicle, or because the brake boo ster has somehow been
damaged , the brake pedal must be pressed considerably harder to
make up for the lack of booster assistance . •
Functioning of A!"lt"-Lock Brake System (ABS)
ABS p revents the wheels from locking up unde r brakin g.
Th e ABS co ntribu tes effect ively to vehicle cont ro l since it preve nts
the whee ls from
locking when the brakes are app lied. This means
t h at the ve hicle rema ins steerable and is less l ikely to s kid.
With ABS you do not need to pump the brake . Just hold the brake
pedal down .
However, do not expec t the A BS to s hor ten bra king d istance u nder
all circumstances. When driving o n grave l or on newly fallen snow
o n t op o f icy sur faces, brak ing d istance may be ev en lon ger, the re
fore, under these c ircumstances, it is especially important that you
driv e slow ly an d with gre at ca re.
How the ABS system works
An a utomatic c heck is m ade w hen a speed of about 1 2 mph (2 0
km/h) is reached. When this happens, a pumping noise can be
h ea rd.