GMC 1976 ZEO 6083 Maintenance Manual page 450

7- 2 TRANSMISSION
GOVERNOR ASSEMBLY
OUTPUT CARRIER AND
INTERNAL GEAR
REAR UNIT INTERNAL
GEAR
SUN GEAR
MAINSHAFT
GOVERNOR DRIVEN
GEAR
GOVERNOR DRIVE
GEAR
OUTPUT FLANGE
Third = 1 .0 :1 gear ratio
INTERMEDIATE SPRAG CLUTCH
CENTER
REAR SERVO
SUPPORT
ASSEMBLY
BOLT
Reverse = 2.08 :1 gear ratio
SPEEDOMETER
DRIVEN GEAR
ASSEMBLY
First and reverse gears can be multiplied by as
much as 2.2 :1, depending upon the slip speed of the
converter pump and turbine.
A vacuum modulator is used to sense engine
torque input to the transmission automatically. The
DETENT
SOLENOID
PUMP
Figure 1-Turbo Hydra-matic Transmission
LINK ASSEMBLY
FORWARD CLUTCH
FORWARD CLUTCH
HUB
DRIVEN SPROCKET
DRIVEN SPROCKET
SUPPORT HOUSING
vacuum modulator transmits this signal to the pres-
sure regulator, which controls line pressure, so that
all torque requirements of the transmission are met
and proper shift spacing is obtained at all throttle
openings .
The downshift solenoid is activated by an adjust-
able switch at the accelerator pedal. When the throt-
tle is opened sufficiently to close this switch, the
solenoid in the transmission is activated, causing a