Post on 03-Apr-2018
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Diagnstico de alineacin para
Camin
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ALINEACIN
DEFINICIN: El proceso por el cual elvehculo y todos las llantas estn viajando enla misma direccin.
Desempea un papel importante en Tire performance
Reducing Tire Costs
Vehicle handling
Driver control
Improving fuel economy
Component life
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8 Components of Alignment
CASTER
CAMBER
KING PIN INCLINATIONTOE
ACKERMAN ANGLE
TURNING RADIUSAXLE PARALLELISM (thrust and scrub)
AXLE SETBACK
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AXLE MISALIGNMENT
1. Drive axle misalignment most frequent
2. Trailer misalignment 2nd most frequent
3. Steer axle misalignment least frequent
1 2 3
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CASTER- Forward or backward tilt ofthe steering axis as viewed from the side
Necessary to provide self aligning forces on steer tires
Assists in turning wheels to straight ahead positionwhen going around corner
Stabilizes vehicle when:
braking
accelerating
Gives directional stability
Decrease susceptibility to crosswinds
Helps offset effects of road crown
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CASTER PROBLEMS
INSUFFICIENT CASTERReduces stability
Vehicle wanders
EXCESSIVE CASTER
Increases steering effort
Can cause a shimmy
Can cause shoulder wear on tires in city operation
INCORRECT CASTER CAUSED BY:Incorrect shims or installed improperly
Sagging springs
Worn shackles and bushings
Twisted axle
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CAMBER- INWARD OR OUTWARD TILT OF THEWHEELS WHEN VIEWED FROM THE FRONT OF THE
VEHICLE
NECESSARY TO :
REDUCE SIDE THRUST
COMPENSATE FOR WEAR ON STEERING KNUCKLECOMPENSATE FOR WEAR ON WHEEL BEARINGS
SHIFT WEIGHT TO INNER WHEEL BEARING
BUILT INTO AXLES - NON ADJUSTABLE
TRUCK WILL LEAD TO THE SIDE WITH MOSTPOSITIVE CAMBER.
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INCORRECT CAMBER
INCORRECT CAMBER CAN CAUSE:
EXCESSIVE TIRE WEARWANDER (PULLS TO SIDE WITH MOST POSITIVE CAMBER)
HARD STEERING
EXCESSIVE TIRE HEAT
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KINGPIN INCLINATION-The amount, in degrees,that the top of the kingpin inclines away from the vertical as
viewing from the front of the truck.
Kingpin Inclination workingtogether with camber angle arecalled Included Angle. IncludedAngle puts the approximate centerof the tire tread in contact with theroad. Kingpin Inclination has theeffect of reducing steering effortand improves directional stability.
Preferred tolerance is 1 degreefrom side to side. Can be used tohelp determine if an axle or spindle
is bent.
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TOE - The inward or outward pointing of the wheelswhen viewed from the top of the vehicle.
Necessary to compensate for tendency of wheelsto deflect rearward when loaded or in motion.
Goal - zero toe when loaded and in motion
Incorrect toe shows up as feathering of tread onboth ends of axle - greatest tire wear problem
Preferred Specs. For radial tiresare .03 to .07 (1/32 to 1/16)
toe-in.
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A feather or saw tooth edgepointing inward will indicateexcessive toe-in
A feather or saw tooth edgepointing outward willindicate a toe-out problem.
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ACKERMAN ANGLE (TOE OUT ON
TURNS)
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CHECKING ACKERMAN ANGLE
Measure WT (width of tires) and WB(wheel base)
Read intersection of WT and WB
Turn outside wheel to 20 degrees, and readturn table dial on opposite side to verify
proper toe out on turns
Preferred Tolerance +/- 2 deg. forOver the road and +/- 1 deg. Forcity
Note: readings from left to rightshould be within 1 degree.
Correction: replace ackerman arm
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AXLE SETBACK
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AXLE PARALLELISM -All axles should beperpendicular to the frameand parallel with each other
(Steer, drive, and trailer)The rear axles are whatdetermine the direction thevehicle is going to travel.
Rear axle misalignmentresult in excessive tire wearon front and rear axles.
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Thrust Angle - axles notperpendicular to frame but are
parallel to each other.
Tends to push vehicle off course
Driver feels pulling
Steer axle tires feather in samedirection
Drive tires show I/W
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Scrub Angle - Axles NOT perpendicular tothe frame and not parallel to each other.
Constant pull in one directionNeed to continually steer against pull
Drives scrub as vehicle is forced to gostraight
Also affects steer tires
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Trailer Thrust will cause DogTracking
Easily visible in tractor mirrorsEffects all tires on tractor andtrailer
Vehicle wanders
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AXLE PARALLELISM IS CORRECTABLE
SOURCES:
Uneven axle springs
Broken leaf springs
Worn springs
Loose U bolts
Bent frame
Adjustment of torque rods /axlesWorn torque rod bushings
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DRAG LINK ANGLE
Parallel to mid-point of spring mounting +/- 15 degreesupward or downward
EFFECT: Bump steer or directional change - steeringstability - no set wear pattern
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Four Damage Conditions
Twist
Side Sway
SagDiamond
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Side Sway
SIDE SWAY
Frame is bentto the side.
Kenworth says if theframe is bent laterally
enough to cause tirewear and handlingissues then the framerails must be replaced.
If someone were to tryand correct the framethen Side Sway should
be corrected first.
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Sag
SAGThe frame is bent
down in the middle.
Kenworth says that ifbent, Frame rails shouldbe replaced- notrepaired.
If someone were tryingto correcting a bentframe rail then Sagwould be corrected after
side sway and before aTwist or Diamond
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Twist
TWISTThe vehicles front
end rolls to one sideand the rear rolls to
the opposite end.
Twist is generally caused by bentcross members. Locate thestrongest Cross members (fromback of cab to back of frame) -they are the ones that usually holdin the twist
Twist normally will show up in thefront because of lighter springs -but is actually held in the back.
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Diamond
DIAMOND
One frame rail has
moved ahead of the
other frame rail.
Caused by bent Crossmembers.
Occurs most often todaywhen a vehicle is hitdirectly on the frame railfront or rear or most likely
if the vehicle has beentowed or pulled on oneframe rail.
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TRUCK ALIGNMENT
RENTON ASSEMBLY
PLANT
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ALLWHEELALIGNMENT
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CHECK RIDE HEIGHT
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ZERO TO FRAME
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CHECK PINION ANGLE
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LATERALOFFSET
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SWAY BARBUSHING GAP
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CHECKTHRUSTBUSHINGS
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CHECKVEHICLELEAN
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INSTALLHEADS
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RUNOUT
COMPENSATION
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CHECKTHRUSTANGLE
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PERFORM AXLE SWEEP
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CENTER
WHEELSAND SET
TOE-IN
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SET UP TO
CHECK REARAXLE SCRUB
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SCRUB ANGLE
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CHECK TURNING RADIUS
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SET AXLE STOPS
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ADJUST BRAKES
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CHECK STEEING SHAFT
ALIGNMENT