afc4_landing gear.ppt

Landing gearLanding gear
The main structural component of an The main structural component of an
aircraft that supports the weight ofaircraft that supports the weight of
the aircraft on land and water.the aircraft on land and water.
8/20/2019 afc4_Landing gear.ppt
operationsoperations
Cushions the landing impactCushions the landing impact Dampens vibrations while taxing andDampens vibrations while taxing and
towingtowing

Provides a means for controlling theProvides a means for controlling theaircraft on groundaircraft on ground
requirementsrequirements
Shock absorberShock absorber !ust be able to absorb the energ" developed!ust be able to absorb the energ" developed
b" the airplane in dropping from a speci#edb" the airplane in dropping from a speci#ed height at maximum landing weightheight at maximum landing weight Drop testDrop test
$ positive means must be provided to$ positive means must be provided to maintain the landing gear in the extendedmaintain the landing gear in the extended position when the aircraft is on ground.position when the aircraft is on ground. Safet" switchesSafet" switches
Down locksDown locks
%round locks &Safet" pins or clips'%round locks &Safet" pins or clips'
(mergenc" means(mergenc" means for extending the landing gear must befor extending the landing gear must be
provided in case of probable failure inprovided in case of probable failure in
the extending s"stem.the extending s"stem. )ndication)ndication
)ndication must be provided for the pilot)ndication must be provided for the pilot if the landing gear is secured in theif the landing gear is secured in the extended or retracted position.extended or retracted position. *ed light*ed light
%reen light%reen light
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+arning+arning Land planes must be provided with an aural warningLand planes must be provided with an aural warning
device that functions continuousl" if the throttles aredevice that functions continuousl" if the throttles are closed and the landing gear is not extended andclosed and the landing gear is not extended and
locked.locked. )f manual shut o, is provided for the warning device-)f manual shut o, is provided for the warning device-
it must be installed in such a wa" that it will resetit must be installed in such a wa" that it will reset when the throttles are opened.when the throttles are opened.
Control knobControl knob
!ust be shaped like a small wheel and tire.!ust be shaped like a small wheel and tire. !ust be located forward of the throttles.!ust be located forward of the throttles.
!ust be easil" operable b" both the pilot and copilot.!ust be easil" operable b" both the pilot and copilot.
classi#cationclassi#cation ased on function &purpose'ased on function &purpose'
!ain landing gear!ain landing gear $uxiliar" landing gear$uxiliar" landing gear
ased on arrangementased on arrangement Conventional landing gearConventional landing gear
Tric"cle landing gear Tric"cle landing gear
ased on dissipation of the landing energ"ased on dissipation of the landing energ" /on0 absorbing landing gear./on0 absorbing landing gear.
Shock absorbing landing gear.Shock absorbing landing gear.
ased on external con#gurationased on external con#guration
1ixed landing gear1ixed landing gear *etractable landing gear*etractable landing gear
ased on no of wheelsased on no of wheels Single wheel landing gearSingle wheel landing gear
!ultiple wheel landing gear!ultiple wheel landing gear
!ain landing gear!ain landing gear
Provides main support of the airplane bothProvides main support of the airplane both on land and water.on land and water.
!a" include combination of!a" include combination of
wheels wheels
2oats and skis2oats and skis shock absorbing equipmentshock absorbing equipment rakesrakes retracting mechanismsretracting mechanisms
Cowling and fairingCowling and fairing structural members andstructural members and hardwarehardware
!a" consists of !a" consists of
$ tail or nose wheel$ tail or nose wheel
SkidsSkids
PontoonsPontoons
Conventional landing gearConventional landing gear
Consists of Consists of Two main wheels & forward of the C%' and one Two main wheels & forward of the C%' and one
tail wheeltail wheel
$dvantages$dvantages Provides good propeller0ground clearanceProvides good propeller0ground clearance
$dvantageous if aircraft operates on rough #eld$dvantageous if aircraft operates on rough #eld
DisadvantagesDisadvantages *estricted visibilit"*estricted visibilit" /osing over/osing over
%round looping%round looping
Tric"cle landing gear Tric"cle landing gear
Two main wheels &aft of the C%' and Two main wheels &aft of the C%' and
a nose wheela nose wheel
+idel" used on modern airplanes+idel" used on modern airplanes
$dvantages$dvantages
$llows more forceful application of the$llows more forceful application of the
brakes with out nosing overbrakes with out nosing over
3,ers better visibilit"3,ers better visibilit"
Tends to prevent ground looping Tends to prevent ground looping
/on absorbing landing/on absorbing landing
gearsgears Don4t have the means to dissipate theDon4t have the means to dissipate the
landing energ".landing energ".
The initial shock of landing absorbed b" The initial shock of landing absorbed b"
this t"pes of landing gears is returned backthis t"pes of landing gears is returned back to the aircraft structure at a later time.to the aircraft structure at a later time.
)nclude)nclude
Shock chord landing gearShock chord landing gear
Spring t"pe landing gearSpring t"pe landing gear
1ixed landing gear1ixed landing gear
This t"pe of landing gear has a #xed This t"pe of landing gear has a #xed
attachment on the aircraft structure.attachment on the aircraft structure.
*emains exposed to the air stream*emains exposed to the air stream
during 2ight increasing drag.during 2ight increasing drag.
1airings and wheel pants can be used1airings and wheel pants can be used
to reduce drag.to reduce drag.
*etractable landing gear*etractable landing gear
Can be drawn &retracted' into aCan be drawn &retracted' into a
housing on the fuselage or the wingshousing on the fuselage or the wings
during 2ight.during 2ight.
This reduces drag at the expense of This reduces drag at the expense of
added weight for the retracting andadded weight for the retracting and
extending s"stems.extending s"stems.
!ultiple wheel landing gear!ultiple wheel landing gear
spreads the weight of the aircraft onspreads the weight of the aircraft on
a larger area.a larger area.
Provides a safet" margin if a tireProvides a safet" margin if a tire
fails.fails.
componentscomponents Landing gear assemblies are made up ofLanding gear assemblies are made up of
various components designed to supportvarious components designed to support
and stabili6e the assembl".and stabili6e the assembl".
Trunnion Trunnion StrutStrut
trunniontrunnion
)s the portion of the landing gear)s the portion of the landing gear
assembl" which is attached to theassembl" which is attached to the
airframe.airframe.
)t is supported at it7s ends b" bearing)t is supported at it7s ends b" bearing assemblies which allow the gear toassemblies which allow the gear to
pivot during extension and retraction.pivot during extension and retraction.
The landing gear strut extends down The landing gear strut extends down from the approximate center offrom the approximate center of
trunnion.trunnion.
di
strutstrut
The vertical member of the landing The vertical member of the landing
gear assembl" that contains thegear assembl" that contains the
shock absorbing mechanism.shock absorbing mechanism.
The top of the strut is attached to -or The top of the strut is attached to -or
is an integral part- of the trunnion.is an integral part- of the trunnion.
The strut forms the c"linder of the air The strut forms the c"linder of the air
oleo shock absorber.oleo shock absorber.
)t is also called the)t is also called the outer cylinder outer cylinder ..
pistonpiston
)s the moving part in the air oleo t"pe)s the moving part in the air oleo t"pe
shock strutshock strut
)t #ts inside the strut.)t #ts inside the strut.
)t7s bottom portion is attached to the axle)t7s bottom portion is attached to the axle or other component on which the axle isor other component on which the axle is
mounted.mounted.

)t is also called)t is also called piston rodpiston rod,, piston tubepiston tube andand inner cylinder inner cylinder ..
torque linkstorque links
$re two airframe t"pe members used$re two airframe t"pe members used
to connect the strut c"linder to theto connect the strut c"linder to the
piston and axle.piston and axle.
The torque links restrict the extension The torque links restrict the extension of the piston during gear retraction andof the piston during gear retraction and
hold the wheel and axle in a correctl"hold the wheel and axle in a correctl"
aligned position in relation to the strut.aligned position in relation to the strut. The" are also called 8 The" are also called 8scissorsscissors 99
trucktruck
)s used when wheels are used in tandem)s used when wheels are used in tandem or in a dual tandem arrangement.or in a dual tandem arrangement.
)s located on the bottom of the piston)s located on the bottom of the piston
with the axles attached to it.with the axles attached to it. )t can tilt fore and aft at the piston)t can tilt fore and aft at the piston
connection to allow for changes inconnection to allow for changes in aircraft attitude during take o,- landingaircraft attitude during take o,- landing
and taxiing.and taxiing. )t is also called a)t is also called a “BOGIE”“BOGIE”
Drag linkDrag link
)s designed to stabili6e the landing)s designed to stabili6e the landing
gear assembl" longitudinall".gear assembl" longitudinall".
)t is hinged at the middle if the)t is hinged at the middle if the
landing gear retracts forward or aftlanding gear retracts forward or aft
to allow the gear to retract.to allow the gear to retract.
)t is also called a)t is also called a drag strut d rag strut ..
Side brace linkSide brace link
)s designed to stabili6e the landing)s designed to stabili6e the landing
gear assembl" laterall".gear assembl" laterall".
)t is hinged in the middle if the)t is hinged in the middle if the
landing gear retracts sidewa"s tolanding gear retracts sidewa"s to
allow for retraction.allow for retraction.
)t is also called the 8)t is also called the 8side strut”side strut”
+heels+heels
$re used for operation on land.$re used for operation on land.
1loats1loats
$re used for operation on water.$re used for operation on water.
SkisSkis
$re used for operation on ice.$re used for operation on ice.
Shock chordShock chord
)s a tightl" wound rubber chord mounted in such a)s a tightl" wound rubber chord mounted in such a
wa" that it will stretch during the landing touchwa" that it will stretch during the landing touch
down.down.
The stretched chord stores the initial landing The stretched chord stores the initial landing
impactimpact The stored energ" is returned to the aircraft The stored energ" is returned to the aircraft
structure during the landing roll.structure during the landing roll.
!ust be replaced periodicall"- especiall" if it is over!ust be replaced periodicall"- especiall" if it is over
: "ears.: "ears. )s color coded to indicate when it was)s color coded to indicate when it was
manufactured.manufactured.
Spring gearSpring gear
)s a single tapered strip or tube of)s a single tapered strip or tube of
strong spring steel bolted to a heav"strong spring steel bolted to a heav"
structural member of the aircraft.structural member of the aircraft.
The axle is bolted to this strut. The axle is bolted to this strut. The strut 2exes and stores the initial The strut 2exes and stores the initial
landing impact.landing impact.

The stored energ" is returned to the The stored energ" is returned to the aircraft structure during the landingaircraft structure during the landing
roll.roll.
Consists ofConsists of
a piston and c"linder arrangementa piston and c"linder arrangement Provides an oil chamber and an ori#ceProvides an oil chamber and an ori#ce
through which oil is forced during landing.through which oil is forced during landing. $ heav" coiled spring$ heav" coiled spring
C ti dC ti d
Continued;Continued;
3peration3peration
when the airplane is airbornewhen the airplane is airborne the strut is extended.the strut is extended.
3il 2ows to the lower chamber.3il 2ows to the lower chamber.
+hen the airplane lands+hen the airplane lands The piston with the ori#ce is forced into the c"linder The piston with the ori#ce is forced into the c"linder
The oil is forced through the ori#ce into the upper The oil is forced through the ori#ce into the upper
chamber.chamber.
The metered oil 2ow provides a cushioning e,ect to The metered oil 2ow provides a cushioning e,ect to absorb the primar" shock of landing.absorb the primar" shock of landing.
$fter touch down$fter touch down The strut collapses and the spring is compressed. The strut collapses and the spring is compressed.
Thus the spring supports the weight of the aircraft on ground- Thus the spring supports the weight of the aircraft on ground-
and during taxing.and during taxing.
Consists of Consists of
$ piston$ piston
The piston with a tapered metering pin The piston with a tapered metering pin
or tube can move up and down throughor tube can move up and down through
the c"linder.the c"linder.
The lower chamber is #lled with oil -and The lower chamber is #lled with oil -and the upper chamber with air.the upper chamber with air.
Continued;;..Continued;;..
3peration3peration
+hen aircraft is airborne+hen aircraft is airborne The lower chamber is #lled with oil and the The lower chamber is #lled with oil and the
upper chamber with air.upper chamber with air.
Continued;;Continued;;
During touch downDuring touch down The piston with the metering pin moves into The piston with the metering pin moves into
the c"linder forcing the oil through thethe c"linder forcing the oil through the
ori#ce.ori#ce.
The metered 2ow reduces the speed at The metered 2ow reduces the speed at
which the piston moves into the c"linder.which the piston moves into the c"linder.
This gives a cushioning e,ect to reduce the This gives a cushioning e,ect to reduce the
shock of landing.shock of landing.
$s the oil moves into the upper chamber the$s the oil moves into the upper chamber the air is compressed providing more cushioningair is compressed providing more cushioning
e,ect.e,ect.
The compressed air will support the weight The compressed air will support the weight
of the aircraft on ground.of the aircraft on ground. $ snubber device prevents the strut from$ snubber device prevents the strut from
extending too rapidl" during take o, orextending too rapidl" during take o, or
during a bad landing.during a bad landing.
Centering devicesCentering devices
The nose wheel piston can swivel inside The nose wheel piston can swivel inside
the c"linder to allow steering on ground.the c"linder to allow steering on ground.
Provision must be made to establish theProvision must be made to establish the
wheel alignment in a straight aheadwheel alignment in a straight ahead direction when the gear is retracted.direction when the gear is retracted.
This is done b"<0 This is done b"<0
(xternal mechanical centering devices or(xternal mechanical centering devices or Centering camsCentering cams
Centering camsCentering cams
$ cam ring is installed near the top of$ cam ring is installed near the top of
the piston to form the upper cam.the piston to form the upper cam.
$nother cam is mounted inside the$nother cam is mounted inside the
bottom of outer c"linder.bottom of outer c"linder.
+hen the strut is full" extended- the+hen the strut is full" extended- the
cam faces mate aligning the nosecam faces mate aligning the nose
wheel in a straight ahead direction.wheel in a straight ahead direction.
CenteringCentering
The following features are also present on The following features are also present on shock struts.shock struts.
$ 2uid #ller inlet and air valve$ 2uid #ller inlet and air valve 1or servicing the shock struts with oil and air1or servicing the shock struts with oil and air
Packing glandPacking gland To seal the sliding 5oint between the outer and lower To seal the sliding 5oint between the outer and lower
c"linders.c"linders.
Packing gland +iper ringsPacking gland +iper rings To keep the sliding surface of the piston free from dirt- To keep the sliding surface of the piston free from dirt-
dust- mud ice and snow.dust- mud ice and snow.
Locking or disconnect pinLocking or disconnect pin
To allow quick turning of the aircraft on ground To allow quick turning of the aircraft on ground
=acking points and towing lugs =acking points and towing lugs
)nstruction plate)nstruction plate Servicing proceduresServicing procedures
Correct t"pe of h"draulic 2uidCorrect t"pe of h"draulic 2uid
Servicing shock strutsServicing shock struts
Proper 2uid and air pressure must beProper 2uid and air pressure must be
maintained for e>cient operation ofmaintained for e>cient operation of
shock struts.shock struts.
To check 2uid level To check 2uid level The shock strut must be de2ated and The shock strut must be de2ated and
compressedcompressed
proceduresprocedures
Position the aircraft in a normalPosition the aircraft in a normal ground position.ground position.
*emove the cap from the air valve.*emove the cap from the air valve.
Check the swivel nut for tightness.Check the swivel nut for tightness.
*elease air pressure trapped between*elease air pressure trapped between
the valve seat and valve core.the valve seat and valve core.
*emove valve core.*emove valve core.
*elease air pressure in the strut*elease air pressure in the strut
(nsure compression of the struts.(nsure compression of the struts. *emove air valve assembl".*emove air valve assembl". 1ill h"draulic 2uid.1ill h"draulic 2uid. *einstall the air valve assembl".*einstall the air valve assembl". *einstall valve core*einstall valve core )n2ate the struts)n2ate the struts Tighten swivel hex nut Tighten swivel hex nut *einstall valve cap*einstall valve cap
l di h kl di h k t t
leeding shock strutsleeding shock struts
leeding might be necessar" if<0leeding might be necessar" if<0 1luid level is low1luid level is low
$ir is trapped in the strut c"linder$ir is trapped in the strut c"linder
leeding is usuall" done with theleeding is usuall" done with the
aircraft on 5acksaircraft on 5acks
dd
proceduresprocedures
Prepare a bleed hose and container.Prepare a bleed hose and container. =ack the aircraft. =ack the aircraft. *elease air pressure.*elease air pressure. *emove air valve assembl".*emove air valve assembl".
1ill the strut with h"draulic 2uid.1ill the strut with h"draulic 2uid. $ttach the bleed hose.$ttach the bleed hose. Place an exerciser 5ack below the struts andPlace an exerciser 5ack below the struts and
compress and extend the struts until air bubbles arecompress and extend the struts until air bubbles are eliminated.eliminated.
*emove the exerciser 5ack.*emove the exerciser 5ack. *emove bleed hose.*emove bleed hose. )nstall air valve and in2ate.)nstall air valve and in2ate.
*etraction s"stems*etraction s"stems
The purpose of retractable landing gear The purpose of retractable landing gear isis
to reduce drag.to reduce drag.
To adapt the aircraft for landing on To adapt the aircraft for landing on di,erent surfaces.di,erent surfaces.
Landing gear retraction s"stems can beLanding gear retraction s"stems can be
!echanical !echanical
)s used)s used 3n older aircraft or3n older aircraft or
3n light aircraft for emergenc"3n light aircraft for emergenc"
extensionextension )s powered b" the pilot moving a)s powered b" the pilot moving a
lever or operating a cranklever or operating a crank
mechanism.mechanism.
(l t i l t ti t(l t i l t ti t
The s"stem includes The s"stem includes !otor for converting electrical energ"!otor for converting electrical energ"
into rotar" motion.into rotar" motion.
$ gear reduction s"stem$ gear reduction s"stem %ears to change rotar" motion into push%ears to change rotar" motion into push
pull movement.pull movement.
Linkage for connecting the push pull toLinkage for connecting the push pull tothe shock strut.the shock strut.
The s"stem is basicall" an electricall" driven The s"stem is basicall" an electricall" driven 5ack for raising or lowering the gears. 5ack for raising or lowering the gears.
+hen a switch is placed in the up position an+hen a switch is placed in the up position an
electric motor operates to retract and lockelectric motor operates to retract and lock
the gears in the up position.the gears in the up position.
+hen the switch is placed in the down+hen the switch is placed in the down
position the motor reverses and moves theposition the motor reverses and moves the
gears down.gears down. The sequence of operations is similar to The sequence of operations is similar to
h"draulic retraction s"stems.h"draulic retraction s"stems.
(lectrical retraction s"stem(lectrical retraction s"stem
Ap0locksAp0locks
3ther components3ther components $re interconnected to permit the proper sequenced$re interconnected to permit the proper sequenced
retraction and extension of the landing gear and theretraction and extension of the landing gear and the landing gear doors.landing gear doors.
g " s"stems"stem
Lowers the landing gears if the mainLowers the landing gears if the main power s"stem fails.power s"stem fails.
Some aircraft have an emergenc"Some aircraft have an emergenc"
release handle in the cockpit- whichrelease handle in the cockpit- which is connected through a mechanicalis connected through a mechanical linkage to the gear up lock.linkage to the gear up lock.
)t releases the up lock allowing the)t releases the up lock allowing the gears to free fall or extend undergears to free fall or extend under their own weight when operated.their own weight when operated.
Landing gear safet" devicesLanding gear safet" devices
$ccidental retraction of a landing$ccidental retraction of a landing gear ma" be prevented b"gear ma" be prevented b"
!echanical down locks!echanical down locks
Safet" switchesSafet" switches %round locks%round locks
$re built in parts of the gear retraction$re built in parts of the gear retraction s"stems"stem
$re operated automaticall" b" the gear$re operated automaticall" b" the gear
retraction s"stemretraction s"stem (lectricall" operated safet" switches are(lectricall" operated safet" switches are
installed to prevent accidental operationinstalled to prevent accidental operation
of the down locks.of the down locks.
Safet" switchesSafet" switches
)s usuall" mounted in a bracket on)s usuall" mounted in a bracket on one of the main gear shock strut.one of the main gear shock strut.
)s actuated b" the linkage through)s actuated b" the linkage through
the landing gear torque links.the landing gear torque links. The torque links spread apart or The torque links spread apart or
move together at the shock strutmove together at the shock strut
piston extends or retracts in thepiston extends or retracts in the c"linder.c"linder.
+hen the aircraft is on the ground the torque+hen the aircraft is on the ground the torque links are close together causing the ad5ustinglinks are close together causing the ad5usting links to open the safet" switches.links to open the safet" switches.
During take0o, as the struts extend the torqueDuring take0o, as the struts extend the torque links close the safet" switch.links close the safet" switch.
$ ground for a solenoid is completed when the$ ground for a solenoid is completed when the safet" switch closes.safet" switch closes.
The energi6ed solenoid locks the selector valve so The energi6ed solenoid locks the selector valve so that the gear handle can be positioned to raisethat the gear handle can be positioned to raise
the gear.the gear. The" are also called The" are also called $$s%uats%uat && switches orswitches or
$'o'&$'o'& switchesswitches
%round locks%round locks
!ost aircraft are equipped with additional!ost aircraft are equipped with additional safet" devices to prevent collapse of thesafet" devices to prevent collapse of the gear when the aircraft is on the ground.gear when the aircraft is on the ground.
3ne common t"pe is a pin stalled in aligned3ne common t"pe is a pin stalled in aligned
holes drilled in two or more units of theholes drilled in two or more units of thelanding gear support structure.landing gear support structure. $nother t"pe is spring loaded clip design to$nother t"pe is spring loaded clip design to
#t around and hold two or more units of the#t around and hold two or more units of the support structure together.support structure together.
$ll t"pes usuall" have red streamers$ll t"pes usuall" have red streamers permanentl" attached to them to readil"permanentl" attached to them to readil" indicate whether the" are installed or not.indicate whether the" are installed or not.
indicator emplo"s<0indicator emplo"s<0
+hen the landing gear is down and+hen the landing gear is down and
lockedlocked $ %reen light for each gear or$ %reen light for each gear or
$ silhouette of each gear and$ silhouette of each gear and
$ +arning light which is o,.$ +arning light which is o,.
+hen the gears are in transit+hen the gears are in transit *ed warning light and.*ed warning light and.
Diagonal red and 2orescent strips.Diagonal red and 2orescent strips.
+hen the landing gears are up and+hen the landing gears are up and lockedlocked +arning light is o,.+arning light is o,.
Tab t"pe indicators. Tab t"pe indicators.
warningwarning
%ear warning devices are incorporated%ear warning devices are incorporated on all retractable gear aircraft.on all retractable gear aircraft.
Asuall" consist o, Asuall" consist o,
$ horn or some other aural device and $ horn or some other aural device and
$ red warning light$ red warning light
The horn blows and the red warning The horn blows and the red warning light comes on when one or morelight comes on when one or more
throttles are retarded and the landingthrottles are retarded and the landing gear is in a position other than downgear is in a position other than down and locked.and locked.
Steering s"stemsSteering s"stems
Steering s"stemsSteering s"stems
$re used to control the direction of$re used to control the direction of movement of an aircraft while taxiing.movement of an aircraft while taxiing.
t"pest"pes
!echanical steering s"stems!echanical steering s"stems Power steering s"stemsPower steering s"stems
Some small aircraft do not have aSome small aircraft do not have a steering s"stemsteering s"stem
Steering is obtained b" the di,erentialSteering is obtained b" the di,erential application of the brakes.application of the brakes.
!echanical steering!echanical steering
s"stemss"stems $re found on small aircraft where the$re found on small aircraft where the
pilot can press on the rudder pedalpilot can press on the rudder pedal
and cause the nose wheel or tailand cause the nose wheel or tail
wheel to turn with out an" form ofwheel to turn with out an" form of powered resistance.powered resistance.
Some aircraft have the rudder pedalsSome aircraft have the rudder pedals
directl" linked to the nose wheeldirectl" linked to the nose wheelsteering arm while others use a springsteering arm while others use a spring
interconnect.interconnect.
Power steering s"stemsPower steering s"stems
$re used for aircraft which require large$re used for aircraft which require large amounts of force to be applied to the noseamounts of force to be applied to the nose
wheel to achieve e>cient steering control.wheel to achieve e>cient steering control.
Power steering s"stems can be controlledPower steering s"stems can be controlled
b"<0b"<0
*udder pedals*udder pedals
$ steering wheel$ steering wheel
" a combination s"stem" a combination s"stem $llowing full directional control with steering wheel and$llowing full directional control with steering wheel and
Small degree of control with the pedals.Small degree of control with the pedals.
3peration of either of the controls causes3peration of either of the controls causes h"draulic pressure to move an actuator on theh"draulic pressure to move an actuator on the nose wheel and changes the direction ofnose wheel and changes the direction of movement.movement.
$ follow up s"stem is used to provide onl" as$ follow up s"stem is used to provide onl" as
much nose wheel de2ection as the pilotmuch nose wheel de2ection as the pilot requires based on the amount the pedal or therequires based on the amount the pedal or the steering wheel is de2ected.steering wheel is de2ected.
$ compensator unit in the s"stem keeps 2uid$ compensator unit in the s"stem keeps 2uid in the steering c"linder pressuri6ed at allin the steering c"linder pressuri6ed at all times.times.
$ safet" valve allows the wheels to trail or$ safet" valve allows the wheels to trail or swivel in the event of h"draulic failure.swivel in the event of h"draulic failure.
(ach steering s"stem usuall" contains(ach steering s"stem usuall" contains $ cockpit control.$ cockpit control. !echanical or h"draulic connection.!echanical or h"draulic connection. $ control unit usuall" a metering valve.$ control unit usuall" a metering valve.
$ source of power usuall" s"stem h"draulic $ source of power usuall" s"stem h"draulic pressure.pressure.
Tubing Tubing Steering c"lindersSteering c"linders $ pressuri6ing assembl" usuall" a compensator$ pressuri6ing assembl" usuall" a compensator
to keep the c"linders pressuri6ed.to keep the c"linders pressuri6ed.
$ follow up mechanism$ follow up mechanism To return the metering valve to the o, position To return the metering valve to the o, position
Safet" valvesSafet" valves

The steering wheel connects through a shaft to a The steering wheel connects through a shaft to asteering drum.steering drum. The rotation of the drum is transmitted to the control The rotation of the drum is transmitted to the control
drum of the di,erential assembl".drum of the di,erential assembl". !ovement of the di,erential assembl" is transmitted!ovement of the di,erential assembl" is transmitted
b" the di,erential link to the metering valve assembl".b" the di,erential link to the metering valve assembl". This moves the selector valve to the selected This moves the selector valve to the selected direction.direction.
S"stem h"draulic pressure is routed through theS"stem h"draulic pressure is routed through the selector valve to one of the steering c"linders.selector valve to one of the steering c"linders.
$ctuation of the c"linders turns the spindle which$ctuation of the c"linders turns the spindle which pivots at a point.pivots at a point. The spindle is attached to the strut. The spindle is attached to the strut.
This turns the nose wheel to the desired direction. This turns the nose wheel to the desired direction.
compensatorcompensator
compensatorcompensator
The valve routes s"stem pressure to The valve routes s"stem pressure to one of the actuators while at theone of the actuators while at the
same time connecting the oppositesame time connecting the opposite
to the return.to the return. The compensator opens to allow 2uid The compensator opens to allow 2uid
into s"stem return when pressure isinto s"stem return when pressure is
developed.developed.
SteeringSteering
p gp g
*eturns the metering valve to the neutral*eturns the metering valve to the neutral position after the nose wheel is de2ectedposition after the nose wheel is de2ected to the selected angle.to the selected angle.
ComponentsComponents
The steering spindle The steering spindle 3ri#ce rod3ri#ce rod Centering camsCentering cams Steering follow up linksSteering follow up links 1ollow up cables1ollow up cables Di,erential assembl"Di,erential assembl" Di,erential linkDi,erential link
1ollow up linkage operation1ollow up linkage operation
p g p
The spindle- as it turns the nose wheel- The spindle- as it turns the nose wheel- drives a pinion gear in the oppositedrives a pinion gear in the opposite
direction.direction.
The pinion gear drives the ori#ce rod which The pinion gear drives the ori#ce rod which
in turn drives the scissor follow up links.in turn drives the scissor follow up links. The follow up links turn the follow up drum- The follow up links turn the follow up drum-
whose movement is transmitted to thewhose movement is transmitted to the
di,erential assembl" b" the follow up cables.di,erential assembl" b" the follow up cables.
This causes the di,erential link to move the This causes the di,erential link to move the
metering valve toward the neutral position.metering valve toward the neutral position.
dampeners'dampeners'
dampeners'dampeners'
The nose wheel has a tendenc" to The nose wheel has a tendenc" to shimm" &oscillate from side to side'shimm" &oscillate from side to side'
due to its geometr".due to its geometr".
$ Shimm" damper is a h"draulic$ Shimm" damper is a h"draulic snubbing device that reduces thesnubbing device that reduces the
tendenc" of the nose gear totendenc" of the nose gear to
oscillate.oscillate.
?ane t"pe?ane t"pe
Steer damperSteer damper
)s mounted on a bracket at the lower)s mounted on a bracket at the lower end of the outer c"linderend of the outer c"linder
Spring loaded reservoir pistonSpring loaded reservoir piston To maintain the 2uid under constant pressure To maintain the 2uid under constant pressure
$n operating c"linder and piston$n operating c"linder and piston
a ball check valvea ball check valve $llows 2ow of 2uid from the reservoir into$llows 2ow of 2uid from the reservoir into
the operating c"linder.the operating c"linder.
$ttached to the inner c"linder and rotates$ttached to the inner c"linder and rotates with the nose wheel.with the nose wheel.
Two cams with lobes which are mirror images Two cams with lobes which are mirror images
of each other.of each other. The lobes are located in such a wa" that maximum The lobes are located in such a wa" that maximum
resistance is o,ered when the wheels are centered.resistance is o,ered when the wheels are centered.
$ cam follower crank with an arm connected to$ cam follower crank with an arm connected to
the operating piston shaft.the operating piston shaft. )ncorporates rollers that follow the cams to restrict)ncorporates rollers that follow the cams to restrict
rotationrotation

Turning of the nose wheel turns the cams Turning of the nose wheel turns the cams The cams push on the rollers of the cam The cams push on the rollers of the cam
followerfollower This tends to rotate the cam follower arm This tends to rotate the cam follower arm
The arm pushes or pulls on the operating The arm pushes or pulls on the operating piston forcing it to move inside the c"linder.piston forcing it to move inside the c"linder.
ut the movement of the piston is restrictedut the movement of the piston is restricted b" the 2ow of the con#ned 2uid through theb" the 2ow of the con#ned 2uid through the
ori#ce on the piston.ori#ce on the piston. This dampens the oscillation of the nose This dampens the oscillation of the nose
wheel.wheel.
or externall"or externall"
The working chamber The working chamber
The lower shaft packing chamber The lower shaft packing chamber
Divided into four sections b"Divided into four sections b" two stationar" vanestwo stationar" vanes
also called abutment 2angesalso called abutment 2anges
g Be"ed to the inner wall of the housingBe"ed to the inner wall of the housing
two rotating vanes.two rotating vanes. $re integral part of the wing shaft$re integral part of the wing shaft
The shaft contains an ori#ce valve through which The shaft contains an ori#ce valve through which 2uid must pass to go from one chamber to the other.2uid must pass to go from one chamber to the other.
$s the shaft is turned in either direction$s the shaft is turned in either direction
The rotating vanes displace 2uid in two of the The rotating vanes displace 2uid in two of the
chambers reducing the volume of the chambers.chambers reducing the volume of the chambers.
Since 2ow of the 2uid is restricted b" the ori#ceSince 2ow of the 2uid is restricted b" the ori#ce
on the shaft sudden rotation of the shaft ison the shaft sudden rotation of the shaft isdamped.damped.
$ bimetallic compensator ad5usts the si6e of the$ bimetallic compensator ad5usts the si6e of the
ori#ce to compensate for temperature changes.ori#ce to compensate for temperature changes.
if exceptionall" high pressure is developed in theif exceptionall" high pressure is developed in the working chamber<0working chamber<0 The closing 2ange moves down -compressing the The closing 2ange moves down -compressing the
spring to allow 2uid to 2ow below the vanesspring to allow 2uid to 2ow below the vanes
Can be used both for steering andCan be used both for steering and shimm" damping.shimm" damping.
PurposePurpose $re used for slowing- stopping- holding-$re used for slowing- stopping- holding-
or steering the aircraft.or steering the aircraft.
*equirement*equirement !ust develop su>cient force to stop the!ust develop su>cient force to stop the
aircraft in a reasonable distance.aircraft in a reasonable distance.
!ust hold the aircraft for normal engine!ust hold the aircraft for normal engine
run up.run up. !ust permit steering of the aircraft on!ust permit steering of the aircraft on ground.ground.
t"pest"pes
Power boost brake s"stemsPower boost brake s"stems
)ndependent brake s"stem)ndependent brake s"stem

)s used on small aircraft)s used on small aircraft )s called independent because it has its)s called independent because it has its

is powered b" master c"lindersis powered b" master c"linders Consists of Consists of 3ne or two master c"linders3ne or two master c"linders !echanical linkages!echanical linkages
To connect the brake pedal to its corresponding To connect the brake pedal to its corresponding
master c"lindermaster c"linder Connecting 2uid linesConnecting 2uid lines rake assembl" on each main landing gearrake assembl" on each main landing gear

(ach master c"linder is actuated b" toe(ach master c"linder is actuated b" toepressure on the brake pedalpressure on the brake pedal uilds up pressure b" the movement of the pistonuilds up pressure b" the movement of the piston
inside a sealed 2uid tight c"linder.inside a sealed 2uid tight c"linder. The resulting h"draulic pressure is transmitted The resulting h"draulic pressure is transmitted
to the brake assembl" on each wheelto the brake assembl" on each wheel each brake assembl" creates the necessar"each brake assembl" creates the necessar"
friction to slow and stop the rotation of thefriction to slow and stop the rotation of the wheel.wheel.
The piston is returned to the o, position b" The piston is returned to the o, position b" the return spring when the pedals arethe return spring when the pedals are released.released.
$ t"pical master c"linder has a$ t"pical master c"linder has a compensating port or valvecompensating port or valve
)t permits the 2uid to 2ow from the)t permits the 2uid to 2ow from the
brake chamber back to the reservoirbrake chamber back to the reservoirwhen excessive pressure is developed inwhen excessive pressure is developed in
the brake line due to an increase inthe brake line due to an increase in
temperature.temperature.
This prevents the brake from locking or This prevents the brake from locking or dragging.dragging.
!aster c"linders!aster c"linders
The two well known t"pes are The two well known t"pes are the %33D($* master c"linders andthe %33D($* master c"linders and
+$*/(* master c"linders.+$*/(* master c"linders.
1luid is fed from an external reservoir1luid is fed from an external reservoir b" gravit".b" gravit".
Parking brake ma" be applied b" aParking brake ma" be applied b" a
ratchet t"pe lock built into theratchet t"pe lock built into the mechanical linkage between themechanical linkage between the
pedals and the c"linder.pedals and the c"linder.
)ncorporates &in a single housing')ncorporates &in a single housing' $ reservoir$ reservoir
Pressure chamber andPressure chamber and
$ Compensating device$ Compensating device The reservoir is vented to the The reservoir is vented to the
atmosphereatmosphere

$re used on aircraft which require$re used on aircraft which require high volume of 2uid for the brakes.high volume of 2uid for the brakes.
)n a t"pical s"stem)n a t"pical s"stem
$ line is tapped o, from the main$ line is tapped o, from the main h"draulic s"stem pressure line.h"draulic s"stem pressure line.
$ check valve is installed in the line to$ check valve is installed in the line to
prevent loss of h"draulic 2uidprevent loss of h"draulic 2uid
S"stem componentsS"stem components Check valveCheck valve
Prevents loss of brake s"stem pressurePrevents loss of brake s"stem pressure $ccumulator$ccumulator
Stores reserve suppl" of 2uid underStores reserve suppl" of 2uid under
pressurepressure +hen pressure drops- 2uid enters from+hen pressure drops- 2uid enters from
the s"stem and is trapped b" the checkthe s"stem and is trapped b" the check
valve.valve.
$lso acts as a surge chamber for excess$lso acts as a surge chamber for excess
loads on the s"stem.loads on the s"stem.

Power brake Control valvesPower brake Control valves *egulate and control the volume and pressure of*egulate and control the volume and pressure of the h"draulic 2uid which actuates the brakes.the h"draulic 2uid which actuates the brakes.
rake Deboost valvesrake Deboost valves *educe the pressure and increase the volume of*educe the pressure and increase the volume of
2uid.2uid. $ntiskid control valves$ntiskid control valves
Close the line to reduce the brake pressure- if theClose the line to reduce the brake pressure- if the wheel tends to skid.wheel tends to skid.
Shuttle valvesShuttle valves
)solates the emergenc" brake s"stem from the main)solates the emergenc" brake s"stem from the main brake s"stembrake s"stem
rake assembliesrake assemblies
Power brake control valvePower brake control valve &spool t"pe'&spool t"pe'
Consists of &in aConsists of &in a housing'housing' $ sleeve$ sleeve
$ spool$ spool
Provides feel to the brakeProvides feel to the brakepedalpedal
$ return spring$ return spring *eturns the spool to the*eturns the spool to the
o, positiono, position
PressurePressure rakerake

The spool moves inside the sleeve closing or The spool moves inside the sleeve closing oropening either the return or the pressure line.opening either the return or the pressure line. +hen brakes are applied+hen brakes are applied
The plunger pushes the spool to open s"stem pressure The plunger pushes the spool to open s"stem pressure portport
The s"stem pressure 2ows to the brakes The s"stem pressure 2ows to the brakes +hen a stead" force is applied+hen a stead" force is applied
The return spring with s"stem pressure compresses the The return spring with s"stem pressure compresses the feel spring closing the s"stem pressure line.feel spring closing the s"stem pressure line.
Constant pressure is maintained in the brake line.Constant pressure is maintained in the brake line.
+hen released+hen released The return spring forces the spool to open the s"stem The return spring forces the spool to open the s"stem
return line releasing brake pressurereturn line releasing brake pressure
PurposePurpose to reduce s"stem pressure and increase volumeto reduce s"stem pressure and increase volume
for brake applicationfor brake application
$ piston with a larger diameter$ piston with a larger diameter
$ check valve$ check valve
$ pintle and$ pintle and
$ reset handle$ reset handle

+hen brakes are applied+hen brakes are applied S"stem pressure acts on the small pistonS"stem pressure acts on the small piston
The force exerted on the small piston is The force exerted on the small piston is
directl" transmitted to the large piston.directl" transmitted to the large piston.
The large piston develops a smaller The large piston develops a smaller
pressure displacing large volume of 2uidpressure displacing large volume of 2uid
which is supplied to the brake assembl".which is supplied to the brake assembl".
+hen brakes are released+hen brakes are released The spring returns the piston backward The spring returns the piston backward

The pintle opens the check valve - if The pintle opens the check valve - if the 2uid in the brake chamber isthe 2uid in the brake chamber is
depleted.depleted.

The reset handle- when operated- The reset handle- when operated- opens a valve to allow 2uid to #ll theopens a valve to allow 2uid to #ll the
brake chamber.brake chamber.

$re used for aircraft that land too fast$re used for aircraft that land too fastto emplo" the independent braketo emplo" the independent brake s"stem but are too light to requires"stem but are too light to require power control valves.power control valves.
)n this s"stem)n this s"stem $ line is tapped o, the main h"draulic$ line is tapped o, the main h"draulic
pressure line.pressure line.
This pressure is used to assist the pedals This pressure is used to assist the pedals through power boost master c"linders.through power boost master c"linders. The s"stem pressure doesn4t enter the brakes. The s"stem pressure doesn4t enter the brakes.
S"stem componentsS"stem components
$ t"pical s"stem consists of $ t"pical s"stem consists of $ reservoir$ reservoir
Power boost master c"lindersPower boost master c"linders
Shuttle valvesShuttle valves rake assembliesrake assemblies
oostedoosted
! i h d li t i t d t th

!ain h"draulic s"stem pressure is routed to the !ain h"draulic s"stem pressure is routed to the power boost master c"linderspower boost master c"linders
+hen the brake pedals are depressed<0+hen the brake pedals are depressed<0 S"stem pressure acts on the master c"linder piston toS"stem pressure acts on the master c"linder piston to
assist the pedals.assist the pedals.
1luid from the master c"linder is forced to actuate the1luid from the master c"linder is forced to actuate the brake assembl"brake assembl"
+hen the pedals are released<0+hen the pedals are released<0 The s"stem pressure port on the master c"linder is The s"stem pressure port on the master c"linder is
closed.closed.
The return spring forces the piston back The return spring forces the piston back The compensator port opens to relief the brake pressure The compensator port opens to relief the brake pressure
oostedoosted

The most commonl" used brake The most commonl" used brake assemblies on aircraft are<0assemblies on aircraft are<0
Single disk brakesSingle disk brakes
Dual disk brakesDual disk brakes !ultiple disk brakes!ultiple disk brakes
Segmented disk brakesSegmented disk brakes
(xpander tube t"pe brakes(xpander tube t"pe brakes
Single disk brakeSingle disk brake

@ousing@ousing
$ piston$ piston
rake lining or puckrake lining or puck

+hen brakes are applied+hen brakes are applied @"draulic pressure from the brake control@"draulic pressure from the brake control unit enters the c"linder- forcing theunit enters the c"linder- forcing the pistons with their pucks against thepistons with their pucks against the
rotating disk.rotating disk. +hen brake pressure is released+hen brake pressure is released
The return spring forces back the pistons The return spring forces back the pistons to their normal positionto their normal position
raking is accomplished b" appl"ingraking is accomplished b" appl"ing friction to both sides of the disk.friction to both sides of the disk.

$re used when more braking action$re used when more braking action is desired.is desired.
Similar to single disk t"pe -exceptSimilar to single disk t"pe -except
that two rotating disks are used.that two rotating disks are used.
!ultiple disk brakes!ultiple disk brakes
$re heav" dut" brakes used with power brake$re heav" dut" brakes used with power brake
$re heav" dut" brakes used with power brake$re heav" dut" brakes used with power brake
control valves or power boost master c"linders.control valves or power boost master c"linders.
$n automatic ad5uster and$n automatic ad5uster and
3ther components3ther components

The bearing carrier is bolted to the The bearing carrier is bolted to the axle 2ange.axle 2ange.
Serves as a housing for the c"lindersServes as a housing for the c"linders
The stationar" disks are ke"ed to the The stationar" disks are ke"ed to the
bearing carrierbearing carrier
The rotors are ke"ed to the landing The rotors are ke"ed to the landing
wheel- therefore- rotating with it.wheel- therefore- rotating with it.
operationoperation

*egulated pressure is applied to a*egulated pressure is applied to a chamber in the bearing carrier.chamber in the bearing carrier.
The pressure forces the annular The pressure forces the annular
piston to move outward compressingpiston to move outward compressingthe rotating and stationar" disks.the rotating and stationar" disks.
The resulting friction causes braking The resulting friction causes braking
action.action.

$re heav"0dut" brakes speciall"$re heav"0dut" brakes speciall"adapted for use with high pressureadapted for use with high pressure h"draulic s"stems.h"draulic s"stems.
!a" be used with either power control!a" be used with either power control
valves or power boost master c"linders.valves or power boost master c"linders. raking is accomplished b" means ofraking is accomplished b" means of
several sets of stationar" high frictionseveral sets of stationar" high friction t"pe brake linings making contact witht"pe brake linings making contact with rotating &rotor' segments.rotating &rotor' segments.
componentscomponents $ carrier assembl"$ carrier assembl"
shimshim $utomatic ad5uster$utomatic ad5uster acking plateacking plate
)nstallation)nstallation
Part of the carrier assembl" is attached to the 2angePart of the carrier assembl" is attached to the 2ange
" g" g on the axle.on the axle.
%rooves or c"linders are machined in the carrier to%rooves or c"linders are machined in the carrier to receive the piston cups and pistons.receive the piston cups and pistons.
(ach rotor plate is notched on the outside(ach rotor plate is notched on the outside
circumference to enable it to be ke"ed to the wheelcircumference to enable it to be ke"ed to the wheeland rotates with it.and rotates with it. The stator plates- with brake lining blocks on both The stator plates- with brake lining blocks on both
sides- are mounted between each of the rotorsides- are mounted between each of the rotor segments.segments.
$ compensating shim is provided following the last$ compensating shim is provided following the last rotor segment so that all the brake lining availablerotor segment so that all the brake lining available for wear is used.for wear is used.
+hen brakes are applied h"draulic+hen brakes are applied h"draulicpressure acts on the piston.pressure acts on the piston.
The piston pushes against the The piston pushes against the
pressure plate and the rotors creatingpressure plate and the rotors creating
friction between the rotors and statorsfriction between the rotors and stators
This provides the breaking action that This provides the breaking action that
slows and stops the rotation of theslows and stops the rotation of the
wheels.wheels.

)s a low pressure brake with EF)s a low pressure brake with EFdegree of braking surface.degree of braking surface.
)s light in weight)s light in weight

@as fewer moving parts@as fewer moving parts !a" be used on large aircraft as well!a" be used on large aircraft as well
as in small aircraft.as in small aircraft.
The frame The frame $ casting bolted to the 2ange on the axle$ casting bolted to the 2ange on the axle
(xpander tube(xpander tube !ade of neoprene reinforced with fabric!ade of neoprene reinforced with fabric
@as a metal no66le through which 2uid@as a metal no66le through which 2uid enters and leaves the tubeenters and leaves the tube
rake blocksrake blocks
+hen brakes are applied<0 pp
1luid from the brake control valve enters the1luid from the brake control valve enters the
expander tube in2ating it.expander tube in2ating it.
The in2ating tube forces the brake blocks The in2ating tube forces the brake blocks
against the rotating brake drum.against the rotating brake drum. The resulting friction causes a braking action. The resulting friction causes a braking action.
+hen brakes are released<0+hen brakes are released<0
The return spring forces the h"draulic 2uid to The return spring forces the h"draulic 2uid to
s"stem return manifolds"stem return manifold

!aintenance must be performed!aintenance must be performed
promptl" and carefull".promptl" and carefull". Check for brake lining wearCheck for brake lining wear
Check for air in the s"stemCheck for air in the s"stem
Check for leaksCheck for leaks
Checking for leaksChecking for leaks

!ake sure that the s"stem is under!ake sure that the s"stem is underoperating pressure.operating pressure.
@owever tighten all #ttings with the@owever tighten all #ttings with the
pressure turned o,.pressure turned o,.
Check all 2exible hose for swelling-Check all 2exible hose for swelling-
cracking or deterioration. *eplace ifcracking or deterioration. *eplace if
deterioration is noted.deterioration is noted.
leeding brakesleeding brakes
purposepurpose to maintain proper 2uid levelto maintain proper 2uid level
To remove air from the s"stem To remove air from the s"stem $ir in the s"stem is indicated b" a spong"$ir in the s"stem is indicated b" a spong"
action of the brake pedalsaction of the brake pedals
There are two general methods There are two general methods
Top down method &gravit" method' Top down method &gravit" method'
ottom upward method &pressureottom upward method &pressure method'method'
precautionsprecautions
!ake sure that equipment is clean and!ake sure that equipment is clean and
proper t"pe of h"draulic 2uid is used.proper t"pe of h"draulic 2uid is used.
!aintain adequate suppl" of 2uid to prevent!aintain adequate suppl" of 2uid to prevent
introduction of air.introduction of air.

Continue bleeding until no more air bubblesContinue bleeding until no more air bubbles are expelled from the s"stem and a #rmare expelled from the s"stem and a #rm
brake pedal movement is obtained.brake pedal movement is obtained.
Check reservoir 2uid level when completeCheck reservoir 2uid level when complete
and check the entire s"stem for leaks withand check the entire s"stem for leaks with brake pressure on.brake pressure on.
$nti0skid s"stems$nti0skid s"stems
PurposePurpose To prevent loss of airplane control on To prevent loss of airplane control on
ground which would be caused b"ground which would be caused b"
skidding of the wheels.skidding of the wheels.
+heel speed sensors+heel speed sensors Detect the rate of deceleration of theDetect the rate of deceleration of the
wheelswheels
*eceives and anal"ses the signal*eceives and anal"ses the signal
Sends a control signal to the valveSends a control signal to the valve
Control valvesControl valves
+heel speed sensors+heel speed sensors

Dc s"stem sensorDc s"stem sensor

)s a small permanent magnet dc)s a small permanent magnet dcgenerator.generator.
The voltage output of the sensor is The voltage output of the sensor is
directl" proportional to the rotationaldirectl" proportional to the rotational
speed of the armature.speed of the armature.
The armature shaft is mechanicall" The armature shaft is mechanicall"
linked with wheel hub.linked with wheel hub.
Control valveControl valve
Pressure from brakePressure from brake
control valvecontrol valve rake pressurerake pressure
operationoperation
PurposePurpose To receive signals from the sensors and To receive signals from the sensors and
send a usable signal to the controlsend a usable signal to the control
valves to prevent skidding of thevalves to prevent skidding of the
wheels.wheels. To prevent brake pressure from being To prevent brake pressure from being
applied prior to touch down.applied prior to touch down.
componentscomponents

ConstructionConstruction
!ost of them are made of aluminum or!ost of them are made of aluminum ormagnesium allo"smagnesium allo"s
Can be cast or forgedCan be cast or forged..
Split 2ange wheelsSplit 2ange wheels
1ixed 2ange wheel1ixed 2ange wheel

+ere used on earl" aircraft where +ere used on earl" aircraft where
th ti 2 ibl h th tthe tires were 2exible enough that
+ere used on earl" aircraft wherethe tires were 2exible enough thatthe tires were 2exible enough that
the" could be forced over the wheelthe" could be forced over the wheel
rim with tire tools.rim with tire tools.
ut modern aircraft tires are sti, thatut modern aircraft tires are sti, that
the" cannot be forced over the rims.the" cannot be forced over the rims.
Can beCan be
$ drop center removable 2ange wheel or$ drop center removable 2ange wheel or
$ drop center removable 2ange wheel or$ drop center removable 2ange wheel or
$ 2at base removable 2ange wheel$ 2at base removable 2ange wheel
@ave a single 2ange held in place b" a@ave a single 2ange held in place b" a
retainer snap ring.retainer snap ring. +heel bearing races are usuall" shrunk+heel bearing races are usuall" shrunk
#tted into the hub of the wheel casing#tted into the hub of the wheel casing with lock nuts on the inner side.with lock nuts on the inner side.
Provide surfaces on which the bearingsProvide surfaces on which the bearings ride.ride.
Split wheelsSplit wheels
)s the most popular t"pe used on most)s the most popular t"pe used on most aircraft toda"aircraft toda"
aircraft toda".aircraft toda". partsparts
)nboard wheel half )nboard wheel half 3utboard wheel half 3utboard wheel half
30ring30ring The inboard and outboard wheel halves The inboard and outboard wheel halves
are bolted together.are bolted together. The o0ring prevents leakage of air from a The o0ring prevents leakage of air from a
tubeless tire through the wheel halftubeless tire through the wheel halfmating surfaces.mating surfaces.
)nboard wheel half )nboard wheel half
The half of the wheel into which the brake #ts. The half of the wheel into which the brake #ts.
*otating brake disks are driven b"*otating brake disks are driven b"
*otating brake disks are driven b"o a g b a e d s s a e d e b" Tangs on the disk which ride in steel reinforced ke" Tangs on the disk which ride in steel reinforced ke"
wa"s.wa"s.
Steel disk ke"s bolted inside the wheel which mateSteel disk ke"s bolted inside the wheel which mate
with slots on the peripher" of the disk.with slots on the peripher" of the disk. PartsParts
%rease seal%rease seal
Covers the bearings to hold grease in the bearing area.Covers the bearings to hold grease in the bearing area.
1usible plugs1usible plugs
!elt and de2ate the tire- if high pressure is developed!elt and de2ate the tire- if high pressure is developed
in the tires.in the tires.
3utboard wheel half 3utboard wheel half
olts to the inboard wheel half olts to the inboard wheel half PartsParts
PartsParts earing cupearing cup
SealSeal Protects the rollers from dirt and water.Protects the rollers from dirt and water.
*etains grease*etains grease
CapCap Covers the axle shaft and the bearingsCovers the axle shaft and the bearings
)s held b" a retaining ring)s held b" a retaining ring
)n2ation valve)n2ation valve Provides a connection point for in2ating the tireProvides a connection point for in2ating the tire
1usible plug
purposepurpose
Provide a cushion of air that helps toProvide a cushion of air that helps to
Provide a cushion of air that helps toProvide a cushion of air that helps to
absorb the shocks and roughness ofabsorb the shocks and roughness of
landings and take o,s.landings and take o,s.
Support weight of the aircraft on groundSupport weight of the aircraft on ground Provide traction for braking andProvide traction for braking and
stopping the aircraft.stopping the aircraft.
T"pe ))T"pe )) @igh pressure@igh pressure
"pe"pe g p essu eg p essu e T"pe )))T"pe ))) Low pressureLow pressure
T"pe )?T"pe )? (xtra low pressure(xtra low pressure
t"pe ?t"pe ? nHanHa
T"pe ?)T"pe ?) Low pro#leLow pro#le
t"pe ?))t"pe ?)) (xtra high pressure(xtra high pressure
T"pe ?))T"pe ?)) (xtra high pressure- high or low speed(xtra high pressure- high or low speed t"pe ?)))t"pe ?))) (xtra high pressure- high or low speed(xtra high pressure- high or low speed
low pro#lelow pro#le
T"pe ))) tires T"pe ))) tires
The most popular low pressure tire The most popular low pressure tire
Section width is wide in relation to theSection width is wide in relation to the
Section width is wide in relation to theSection width is wide in relation to the
bead diameter.bead diameter.
$llows low in2ation pressure for improved$llows low in2ation pressure for improved
2oatation and cushioning.2oatation and cushioning.
The section width and bead diameter The section width and bead diameter
are used to designate the si6e of theare used to designate the si6e of the
tiretire e.g. I.:F0JEe.g. I.:F0JE
$ standard for 5et aircraft$ standard for 5et aircraft
Si6e is designated b" outsideSi6e is designated b" outside
diameter and section width.diameter and section width. (.g. KxJ(.g. KxJ
T"pe ?))) tire T"pe ?))) tire
$re used for high performance 5et$re used for high performance 5et
aircraftaircraft

@ave a low pro#le.@ave a low pro#le. Si6e designation includes outsideSi6e designation includes outside
diameter section width and rimdiameter section width and rim
diameter. diameter.
Pl" ratingPl" rating
3ld tires were rated for strength b"3ld tires were rated for strength b" number of cotton fabric plies used innumber of cotton fabric plies used in
number of cotton fabric plies used innumber of cotton fabric plies used in the construction of the carcass.the construction of the carcass.
ut newer materials have muchut newer materials have much
greater strength than the cotton.greater strength than the cotton. Pl" rating is a parameter thatPl" rating is a parameter that
indicates the number of plies ofindicates the number of plies of
cotton fabric needed to produce thecotton fabric needed to produce thesame strength as the actual plies.same strength as the actual plies.
Tube t"pe and Tubeless tires Tube t"pe and Tubeless tires
Tubeless Tubeless
@as an inner liner about one tenth of an@as an inner liner about one tenth of an
@as an inner liner about one tenth of an@as an inner liner about one tenth of an
inch thick that serves as a container forinch thick that serves as a container for
the air.the air.
Tubeless tires are identi#ed b" the word Tubeless tires are identi#ed b" the word tubeless on their side wall.tubeless on their side wall.
Tube t"pe tires have no such liner. Tube t"pe tires have no such liner.
Tire construction Tire construction
$ircraft tires must be strong to$ircraft tires must be strong to
absorb the tremendous loads ofabsorb the tremendous loads of
landing.landing.
The" must also operate at high The" must also operate at high
speeds.speeds.
The bead The bead
The bead The bead
$nchors the carcass and provides a #rm$nchors the carcass and provides a #rm
mounting for the tire on the wheel.mounting for the tire on the wheel.
$ll the ground forces terminate on the bead$ll the ground forces terminate on the bead
)s made of bundles of high strength steel)s made of bundles of high strength steel
wire. wire. *ubber apex strips stream line the beads so that*ubber apex strips stream line the beads so that
the fabric #ts smoothl".the fabric #ts smoothl".
1lippers are la"ers of rubber and fabric that1lippers are la"ers of rubber and fabric that
enclose the bead.enclose the bead. )nsulate the fabric from the bead wires)nsulate the fabric from the bead wires
The carcass The carcass
)s made up of la"ers of rubber coated fabric.)s made up of la"ers of rubber coated fabric.
The fabric is cut into strips. The fabric is cut into strips.
pp
The cords of the fabric run at : degrees to The cords of the fabric run at : degrees to
the length of the strip.the length of the strip.
The strips extend completel" through the The strips extend completel" through the tire and lap back over the beads to form thetire and lap back over the beads to form the
pl" turn ups.pl" turn ups.
Cha,ers enclose the entire bead areaCha,ers enclose the entire bead area
Provide chafe resistance with the wheel.Provide chafe resistance with the wheel.

afc4_landing gear.ppt

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