Pontiac FIREBIRD 1972 Service Manual page 924

7E-34 1972 PONTIAC SERVICE MANUAL
2. 1-2 Accumulator Valve
3. Detent Regulator Valve
4. 1-2 Shift Valve
Lo oil acts on the detent regulator valve. Combined with
the detent spring, Lo oil holds the detent valve against line
oil acting on the detent valve, causing drive oil to flow
through the detent regulator valve into the detent and
modulator passages. Modulalator and detent oil at line
pressure, acting on the 1-2 regulator and 1-2 detent valve,
BASIC CONTROL
overcomes governor oil and Lo oil on the 1-2 shift valve
at any vehicle speed below approximately 40 mph and the
Lo oil flows past a ball check to the apply side of the rear transmission will shift to first gear.
servo piston and to the 1-2 accumulator valve to raise the
1-2 accumulator oil to line pressure for a smooth band
In first gear
-
Lo range, the transmission cannot upshifi
apply.
to second gear regardless of vehicle or engine speed.
POWER FLOW
S U M M A R Y
The forward clutch and rear band are applied. The transmission is in Lo
range
-
first gear.
REVERSE RANGE-REVERSE GEAR
Forward Clutch
-
Released
Roller Clutch
-
Ineffective
Direct Clutch
-
Applied
Front Band - Released
Rear Band
-
Applied
Intermediate Clutch
-
Released
Intermediate Sprag
-
Ineffective
Detent Solenoid
-
De-energized
In reverse gear, the direct clutch is applied to transmit
turbine torque from the forward clutch drum to the sun
gear shaft and sun gear. The rear band is also applied,
preventing the reaction carrier from turning clockwise.
Clockwise torque to the sun gear causes the front pinions
!and front internal gear to turn counterclock- wise in re-
'duction. The front internal gear is connected directly to
'the output shaft, thus providing the reverse output gear
ratio of approximately 2.00:l. The reverse torque multi-
Iplication at stall (converter and gear ratios) is approxi-
imately 4.00: 1.
OIL FLOW
When the selector lever is moved to the Reverse position
the manual valve is repositioned to allow line pressure tc
enter the reverse circuit. Reverse oil then flows to the:
I . Direct Clutch
2. 2-3 Shift Valve
3.
Rear Servo Piston
4. Pressure Boost Valve
BASIC CONTROL
Reverse oil from the manual valve flows to the large area
of the direct clutch piston and to the 2-3 shift valve. From
the 2-3 shift valve, it enters the direct clutch passage and
is directed to the small area of the direct clutch piston to
apply the direct clutch.
Reverse oil flows to the rear servo and acts on the servo
piston to apply the rear band. Reverse oil also acts on the
pressure boost valve to boost line pressure.
S U M M A R Y
The direct clutch and the rear band are applied. The transmission is in
Reverse range
-
reverse gear.