GMC 4000 Series Service Manual page 480

Section
9A
9B
Section
D e s c r ip tio n ............................................................................................
Steering System Maintenance
Steering Gear Adjustments
Steering Gear Replacement
Steering Linkage
Steering Tie R o d ..................................................................................
Steering Wheel and Column
Multiple Wire Connectors
Steering Wheel R e p la ce m en t............................................................
Steering Column and Shaft
Cab and Cowl Models
P-M odels
Tilt Cab Models
Trouble Diagnosis C h a r t ...................................................................
Specifications
DESCRIPTION
Rotation of the steering wheel is transmitted
to the front axle right and left steering arms from
the steering gear pitman arm by linkage consisting
of a drag link and tie rod. Toe-in is also adjusted
and maintained through use of the tie rod.
Steering shaft on cab models is of one-piece
construction and uses a rag-type flexible coupling
to connect shaft to steering gear worm shaft. Tilt
cab, "P," and cowl models use a two-piece shaft
arrangement comprised of two universal yoke-type
joints and a splined shaft and sleeve which is e s­
sential to permit movement of shaft while revolv­
ing. Ball bearings are provided at upper and lower
ends of steering column, to center steering shaft in
column, and to ensure smooth operation of steering
system . Components of column and shaft(s) which
are subject to wear are replaceable, and methods
used for repair are described in detail later.
A recirculating ball bearing and sector nut
type steering gear, mounted on left frame side rail
forward of front wheels, is used on all vehicles
G M C S E R V I C E M A N U A L
SECTION 9
Ste&Una Su&tem
Contents of this section are listed in Index below:
Mechanical S te e r in g .........................................................
Power Steering ................................................................
SECTION 9A
Mexdtanloai Btee/tina
Contents of this section are listed in Index below:
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Page No.
Page No.
covered by this manual. This unit is adjustable for
normal wear.
Steering gear assem blies, while similar in
construction, vary in size and mounting, depending
on truck model application. Refer to "Model Ap­
plication Chart" at end of this section for proper
steering gear application on each truck series.
The major differences in the steering gear
assem blies are described in the following text:
NOTE: Refer to "Steering Gear Adjustments"
later in this section for adjustment of Pitman shaft
lash, back-up adjuster, and worm thrust bearings.
The type 549-D and 553-D steering gear a s­
sem blies shown in figure 1 have an adjuster as­
sembly at shaft end of gear housing for adjustment
of worm thrust bearing; lip-type oil seals at steer­
ing worm and Pitman shaft; shims for adjustment
of Pitman shaft lash, and bushings in gear housing
and side cover. A back-up adjuster is used on the
553-D -17 type steering gear to prevent the worm
shaft from flexing up and down. Figure 5 shows
tilt cab steering gear and linkage components.
Sec. 9A
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