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7
-2
DESCRIPTION
STEERI NG GEAR
_
AND TIE RODS
(
234 )
Series 70
Series 40-50
Toe-in,
Caster ,
Camber,
etc
-
.
P
itman
Shaft D
iameter-Long End
~
.
Clearance in
Bushings
.
Pitman
Shaft
Diameter-Short End
.
Clearance
in Bushing
.
Items
Number
a
nd T
y pe of
Steering Sha ft
Bearin gs
_
Lower End
.
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0(
2 Roller Bearings
~
Upper End
+--
- 1
Ball Be
aring
~
Worm and
Nut
Ba ll Bearin gs-No.
and Diameter
.
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+--
- - -
-60,
%2"- -
- - ---+
Adjusting Screw a
nd
S
him
Cleara n ce in Pitman
Shaft.
.
.
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.
.
. +-
0 t
o
.002
"
--+
Worm
T
hrust Bearing
Adjustmen t - L bs
.
Pull at Wheel
Rim
+-
%
to
1%
~
Pitman Shaft Lash
Adjustment-L
bs.
Pull at Wheel Rim
0(
2 to
2
~
~
Tie R
od Plug
Ad
justment
.
.
.
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+--Tighten
Plug
Solid-----+
+-- -Back
Off 2±
turns-
---+
+-
-
-See
figure
6-36
)-
+--
-
-1.
1205"
to
1.1210"- ~
+--
-
- .0035"
to .0045"
~
-+---
-
1. 1235" to
1.1240"
~
+---
-
.0015 "
to .0025
"·
-
..
---+-
PITMAN
SHAFT SECTOR
Figure
7-1-Steering
Gear Worm and Nut
, Showing
Ball Circuits
7 -2 DESCRIPTION OF STEERING
GEAR
AND TIE RODS
a. Steering Gear
Assembly
The
steer ing gea r is
the recirculat
ing ball
worm
and nu
t t
ype. The worm on lower end
of the
steering shaft a
nd
the
t
all n
ut
wh
ich is
mounted
on
t
he
worm
have
mat ing spiral
grooves
in which steel
ball s
circ
ulate to pro-
vide a
frictionless
drive
between wo
r m and
nut. See
figure
7-1.
Two
sets of
30 ba
lls
are used, with each set
operating
independentlg
of
the other. The
cir-
cuit t
h rough which
each set of ba
lls
circulates
includes t
he
grooves in worm and ball nut and
a ball return g
uide
attached to outer surface of
t
he
n
ut.
When the wheel and steering sh
af t turn
to
the left the ball nut
is moved
dow
nward
by
the
balls which roll
between the
worm and nut.
As the balls reach the
outer surface
of nut
they enter the
r
et urn guides which
direct
them
across a
nd
down into the ball nut, where they
ent er t
he
circuit again. When
a
right turn is
made,
the
ball
n
ut
moves
upward
and t
he balls
circulate in t
he
r
everse
direction.
See fig ure
7-1.
Teeth
on
the ball nut engage t
eeth
on a
sector forged
integral
with
t
he pitman
shaft .
The teeth
on
the ball n
ut a
re
made so that a
"high point" or
tighter fit
exist s
between
the
ball nut and pitman
shaft
secto r
teet h
when
front
wheels
are in
the
st raight -ahea d
posi-
t
ion.
The teeth of sector
are slightl y
t
aper
ed
so that a
pr oper
lash
may
be
obt ained
by mov-
Figu re
7-2
- End Sect
io nal Vie w
of Stee ring Ge
a r
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