GMC 1976 ZEO 6083 Maintenance Manual page 643

12- 38 CHASSIS ELECTRICAL
ENGAGE
TERMINAL
OUTPUT TO
SPEEDOMETER
INPUT FROM
TRANSMISSION
ORIFICE TUBE AND
CONNECTOR
ASSEMBLY
AIR FILTER AND SOLENOID
HOUSING COVER . .,o,
Figure 54-Transducer
begins to supply more bleed air (vehicle speed in-
creasing), the vacuum in the chamber drops and the
diaphragm moves away from the vacuum port . In
operation, at cruise speed, a proper balance of air and
vacuum is blended at the "Tee" fitting and is im-
posed upon the servo unit to maintain and "on
speed" cruise condition.
Figure 56-Transducer Cross Section
CONTROLLED VACUUM
SUPPLY FROM TRANSDUCER
VACUUM
CHAMBER
Figure 55-Servo Unit
An additional function of the transducer is to
drive the speedometer. Since the vehicle speed is
sensed by a speedometer-like mechanism within the
unit, the speedometer cable from the transmission
drives the regualator which drives a second cable (at
a one to one ratio) to the speedometer.
SIDE VIEW SECTION
END VIEW SECTION
CONTROL VALVE
CLUTCH SPRING
LOCKNUT
ORIFICE TUBE &
CONNECTOR ASSEMBLY
A-4249