Pontiac FIREBIRD 1972 Service Manual page 922

7E-32 1972 PONTIAC SERVICE M A N U A L
POWER FLOW
Forward Clutch
-
Applied
Roller Clutch
-
Ineffective
Direct Clutch
-
Released
Front Band
-
Applied
Rear Band
-
Released
Intermediate Clutch
-
Applied
Intermediate Sprag
-
Effective
Detent Solenoid - De-energized
SUPER RANGE-SECOND GEAR
In second gear, the intermediate clutch is applied to allow
the intermediate sprag t o hold the sun gear against coun-
terclockwise rotation. Turbine torque, through the for-
ward clutch, is now applied through the mainshaft to the
rear internal gear in a clockwise direction.
Clockwise rotation of the rear internal gear turns the rear
pinions clockwise against the stationary sun gear. This
causes the output carrier and output shaft t o turn clock-
wise in a reduction ratio of approximately 1.5:l.
I n second gear, engine braking is provided by the front
band as it holds the sun gear fixed. Without the band
applied while coasting, the sun gear would overrun the
intermediate sprag.
OIL FLOW
When the selector lever is in Super, intermediate oil from
the manual valve is directed t o the:
1. Pressure Boost Valve
2. 2-3 Shift Valve
Intermediate oil at the boost valve will increase line pres-
sure to 150 psi. This increased intermediate oil pressure at
the 2-3 shift valve will close the 2-3 shift valve, regardless
of car speed.
F o r engine braking, the front band is applied by exhaust-
ing servo oil at the manual valve. This allows intermediate
clutch oil, acting on the servo piston, t o move the piston
and apply the front band. Once the transmission is in
second gear-Super, it cannot upshift t o third gear regard-
less of vehicle speed.
SUMMARY
T h e forward and intermediate clutches and front band are applied. T h e
transmission is in Super range-second gear.
LO RANGE-FIRST GEAR
POWER FLOW
Forward Clutch
-
Applied
Roller Clutch
-
Effective
Direct Clutch
-
Released
Front Band
-
Released
Rear Band
-
Applied
Intermediate Clutch
-
Released
Intermediate Sprag
-
Ineffective
Detent Solenoid
-
De-energized
clockwise. In turn, the sun gear drives the front pinions
clockwise, thus turning the front internal gear, output
carrier and output shaft clockwise in a reduction ratio of
approximately 2.5:l. The reaction of the front pinions
against the front internal gear is taken by the reaction
carrier and roller clutch t o the transmission case (Total
stall ratio equals approximately 5.00: 1).
Down hill o r overrun braking is provided in L o range by
applying the rear band as this prevents the reaction carrier
from overruning the roller clutch.
With the selector lever in L o range, the forward clutch is
applied. This delivers turbine torque t o the mainshaft and OIL FLOW
turns the rear internal gear in a clockwise direction (Con-
verter torque ration equals approximately 2.00: 1 at stall). Maximum downhill braking can be attained a t speeds
below 40 mph with the selector lever in L o range, as thjs
directs Lo oil from the manual valve to the:
Clockwise motion of the rear 'internal gear causes the rear
pinions to turn clockwise t o drive the sun gear counter-
1. Rear Servo