Chevrolet 10 1971 Series Chassis Service Manual page 435

G e n e ra l D e s c r i p t i o n ....................................................... .....................15-1
System O pe ra tio n s . . ...................................................................... 15-1
C ru is e M a s te r U n its ......................................................................... 15-1
Service O p e r a t io n s ............................................................................... 15-2
B rake R e le a se S w i t c h e s ................................................. ...............15-2
E l e c t r i c ............................................................................................15-2
V a c u u m ...............................................................................................15-3
The Cruise-Master is a speed control system which
employs engine manifold vacuum to control the throttle.
The Servo moves the throttle when speed adjustment
is necessary by receiving a varying amount of con­
trolled vacuum from the Regulator Unit. The speedo­
meter cable from the transmission drives the Regulator,
and a cable from the Regulator drives the instrument
panel speedometer.
The engagement of the Regulator Unit is controlled by
an Engagement Switch located at the end of the turn signal
lever. Two brake release switches are provided. An
electric switch disengages the Regulator Unit and a vacuum
(switch) valve decreases the vacuum in the Servo Unit
to quickly return the throttle to idle position.
The operation of each unit of the system and the opera­
tion of the entire system under various circumstances is
described below. Figure 1 shows the location of the
system components within the vehicle.
SYSTEM OPERATION
ENGAGEMENT
The driver accelerates to the speed at which he desires
to cruise and depresses then slowly releases the cruise
control engagement switch button located at the end of the
directional signal lever or bottom of the instrument panel.
The cruise system takes over speed control and, within
engine limitation, maintains this speed regardless of
changes in terrain.
The Engagement Switch button performs these functions:
1. When partially depressed, it engages the system.
2. When depressed fully and held there, it disengages the
system.
3. When released completely, it holds the system in
engagement. (The lowest speed at which the system
should be used is 40 MPH.)
SECTION 15
ACCESSORIES
CRUISE MASTER
INDEX
Page
Engagem ent S w itc h ............................................................................ 15-3
Servo U n i t ........................................................................................... 15-4
R e g u la t o r .............................................................................................. 15-4
E le c tr ic a l System C h e c k ................................................................15-4
Engagem ent Sw itch T e s t ................................................................ 15-4
H arn e ss T e s t ..................................................................................... 15-4
Servo and V acuum System C h e c k ..............................................15-6
GENERAL DESCRIPTION
SPEED ADJUSTMENT
Upward
Depress the accelerator pedal to the new desired speed.
Then, fully depress and slowly release the cruise control
engagement switch button. The system re-engages at the
higher speed when the button is slowly released.
Downward
Disengage the system by depressing the engagement
switch button fully and holding it there until the car has
decelerated to the new desired speed; then release the
button slowly.
OVERRIDE
The accelerator pedal'may be depressed at any time to
override the cruise system. Release of the accelerator
pedal will return the car to the previous cruise speed.
THE ENGAGEMENT SWITCH (Fig. 2)
The Engagement Switch which is located at the end of the
directional signal lever is used to control the system and
for upward and downward speed adjustments.
THE REGULATOR UNIT (Fig. 3)
The Regulator is mounted in the speedometer cable line.
It is a combination speed sensing device and control unit.
When engaged, it senses vehicle speed and positions the
Servo Unit to maintain the selected speed.
BRAKE RELEASE SWITCH AN D
VALVE (Fig. 4)
disengage the system electrically and pneumatically when
CRUISE-MASTER UNITS
These units are mounted on the brake pedal bracket and
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10-30 CHEVROLET TRUCK SERVICE MANUAL