GMC 4000 Series Service Manual page 56

Maintenance information on windshield wipers, windshield and rear
window glass replacement, and cab painting is explained in "GENERAL
MAINTENANCE" section at beginning of this group. Refer to LUBRICA­
TION (SEC. 0) for cab lubrication information. Contents of this section
are listed in Index below:
Subject
D e s c r ip tio n ...................................
Cab Tilting Instructions
Cab Mountings
I n s u la tio n .......................................
Seats
D o o r s ..............................................
Cab Ventilation and Heating
Cab R e p la c e m e n t.........................
Torsion Bar Replacement
Torsion Bar Tension Adjustment
CAB DESCRIPTION
The "L" Model is a tilt cab type of all-steel
welded construction (fig. 1). Cab fully surrounds
engine and can be tilted 55 degrees to expose en­
gine for servicing. The cab tilting mechanism is
integral with cab front mountings and tilting is
accomplished by means of a torsion bar extending
across cab front hinge mountings. One end of tor­
sion bar is anchored to cab, whereas opposite end
is anchored to chassis. Cab is retained in lowered
(operating) position by positive locking mechanism
located at rear of cab.
Access for minor engine servicing, such as
oil and engine coolant, is accomplished without
tilting cab through access doors in panel at rear
of passenger seat and at top of seat back riser. A
concealed step is constructed in floor of each door
opening. Also, a central island shifting area that is
not disturbed with the cab tilted, is located be­
tween the seats. Island contains transmission shift
lever, hand brake lever and ignition or control
switch.
Two-piece windshield is retained in cab open­
ings with a one-piece rubber seal expanded into
position by a small rubber insert. No sealing com­
pound or cement is used. Rear window glass and
rear side glass is retained in same manner as
windshield glass.
Doors are on swing-out type hinges with the
upper hinge incorporating a spring-loaded door
check for holding door open. Door is retained at
the rear by a striker bolt on cab pillar. Outside
handles are stationary-type screw retained to door
and have a push button-type latch control.
G M C S E R V I C E M A N U A L
l i l t Gab
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Page No.
Vent window in forward portion of door is of
friction-type having a positive theft-resistant latch.
Friction mechanism consists of a nylon bushing on
lower pivot of vent which exerts frictional force
against tension clamp mounted to door paneling.
Outside air enters cab through a vent directly
in front of driver and through the outside air heat­
ing system. Air entry from outside of cab is made
through a louvered, removable panel, located in
front center of cab just above radiator grille open­
ing. Air flows through plenum chamber between
Figure 1— Tilt Cab Interior Construction
Sec. 1
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