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WHEEL ALIGNMENT
WHEEL ANGLES
For the vehicle to have good steering properties and
a minim um of tyre wear, t he front w hee ls
mu st
ha ve
certa in pre-dete
rmin
ed
settings,
ge nera
lly
know
n
as
the whee
l
a ng les. The w hee
l
a ng les refe
r
to the
caster,
camber, king
pin
incli nation
,
toe -o
ut
and toe-
in
.
CASTER
easter generally refers to the long
itu
dina
l
inclination
(forwards or
backwards)
of the
kin
g pin. As
th
is ve-
hicle does not have a king pin, the caster consists of
the ang le betwee
n
a vertica
l lin
e a nd a line thro ug
h
the centre of t he ba
ll
joints (Fig. 6-5).
easter has
th
e effect of caus ing t he w hee ls to
run
stra ight forwards thereby fac ilitating the steering.
CAM
BER
ea mbe
r
is
th
e
in
Cl
in
a
tion
of
th
e whee
l
itse lf
outward
s
or inwa
rds. It
is positive
if th
e whee
l
is
in clined
out-
wards
(se
e e
,
Fig.
6-6) an
d
neg
a
tive if th
e
wheel in-
clin
e
s inwards.
Fa
ulty camber
causes
uneven tyre
wear.
Fig.
6-5.
Caster
VOLVO
23801
VERT
leAL LI
NE
VOLV
O
238 02
Fig. 6-6.
Ca mbe
r
a nd
king
p
in
inclina
ti
o
n
B=K
in
g
pin inclin
ation C=Ca mber
KING PIN INCLlNATION
King pin inclination
means
the inclination of the king
pin
inwards. Since
this car does not have a king pin,
the inclination is represented by an angle made
be-
tween a
verticle
line and a
line
through the centre
of the ball joints (B, Fig. 6-6).
King pin inclination
causes
the centre
lines
of the ball
joints and the wheel to approach each other towards
the road surface. This makes the wheel easier to turn
.
The indination also assists the tendency of the wheel
to run straight forwards since the car is lifted very
slightly when the wheels are turned
.
TOE-OUT
When driving round a bend, the wheels roll at
dif-
ferent radii. For them to have the same pivoting
centre, and consequently minimum tyre wear, the front
wheels must be turned to diffe
rent exte
nts. This
re
-
lationship is determined by
the
sh ape of the steerin
g
rod and steering arms,
see
Fig. 6-7.
6
:
3
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