Page 1020 of 1463

AUTOMATIC TRANSMISSION 5A-43
Figure 4.1 - Power Flow Diagram
TORQUE CONVERTER
The torque converter (refer figure 4.2) consists of a turbine,
stator pump, impeller and a lock-up damper and piston
assembly. As in conventional torque converters, the impeller is
attached to the converter cover, the turbine is splined to the
input shaft and the stator is mounted on the pump housing via
a one way clutch (sprag).
The addition of the damper and piston assembly enables the
torque converter to ‘lock-up’ under favourable conditions. Lock-
up is only permitted to occur in third and fourth gears under
specified throttle and road speed conditions.
Lock-up is achieved by applying hydraulic pressure to the
damper and piston assembly which couples the turbine to the
converter cover, locking-up the converter and eliminating
unwanted slippage. Whenever lock-up occurs, improved fuel
consumption is achieved. Torsional damper springs are
provided in the damper and piston assembly to absorb any
engine torque fluctuations during lock-up.
Figure 4.2 - Torque Converter Cross Section
Page 1021 of 1463
5A-44 AUTOMATIC TRANSMISSION
CLUTCH PACKS
There are four clutch packs (refer to figure 4.3). All clutch packs are composed of multiple steel and friction plates.
C1 CLUTCHWhen applied, this clutch pack allows the input shaft to drive the planet carrier.
This occurs in third and fourth gears.
C2 CLUTCHWhen applied this clutch pack allows the input shaft to drive the forward sun gear via the 3-4 OWC.
This occurs in all forward gears.
C3 CLUTCHWhen applied this clutch pack allows the input shaft to drive the reverse sun gear. This only occurs in
reverse gear.
C4 CLUTCHWhen applied this clutch provides engine braking on overrun. This occurs in Manual 1, 2 and 3 and
also Drive 2 and Drive 3 to prevent objectionable free wheel coasting.
Figure 4.3 - Clutch Packs
Page 1022 of 1463

AUTOMATIC TRANSMISSION 5A-45
BANDS
The transmission utilises two bands, the B1 band (sometimes known as the 24 band), and the B2 band (sometimes
known as the low-reverse band). Refer to figure 4.4.
The B1 band is a flexible band which is engaged by the front servo piston. B1 is activated in second and fourth gear.
When activated B1 prevents the reverse sun gear from rotating by holding the C3 clutch assembly stationary. In
second gear only the outer area of the apply piston is utilised. In fourth gear both areas are utilised for greater
clamping force.
The B2 band is a solid band which is engaged by the rear servo piston. B2 is activated in Park,
Reverse, Neutral and Manual 1. When activated B2 prevents the planet carrier assembly from rotating. In Manual 1
only the inner area of the apply piston is utilised. In Park, Reverse and Neutral, both areas are utilised for greater
clamping force.
Figure 4.4- Bands
ONE WAY CLUTCHES
The transmission uses two OWCs, the 1-2 OWC and the 34 OWC. (Note that a third OWC is located in the torque
converter, also known as a sprag.)
The 1-2 OWC is located between the planetary carrier assembly and the centre support. This allows the carrier to
rotate around the centre support in one direction only. The one way clutch is engaged only in Drive 1.
The 3-4 OWC is located between the C4 and the C2 clutch assemblies. This allows the C2 clutch to drive the forward
sun gear in first, second and third gears but unlocks in fourth gear and during overrun.
PLANETARY GEAR SET
The planetary gear set used in the transmission is a conventional six pinion Ravigneaux compound gear set.
Page 1023 of 1463
5A-46 AUTOMATIC TRANSMISSION
PARKING MECHANISM
When Park is selected the manual lever extends the park rod rearwards to engage the parking pawl (refer to (figure
4.5). The pawl will engage the external teeth on the ring gear thus locking the output shaft to the transmission case.
When Park is not selected a return spring holds the parking pawl clear of the output shaft, preventing accidental
engagement of Park.
Figure 4.5 - Park Rod and Cross Shaft
Page 1024 of 1463
AUTOMATIC TRANSMISSION 5A-47
POWER FLOWS
INTRODUCTION
The power flows for the various transmission selections are listed below:
lPower Flow - Neutral and Park
lPower Flow - Reverse
lPower Flow - Manual 1
lPower Flow - Drive 1
lPower Flow - Drive 2
lPower Flow - Drive 3
lPower Flow - Drive 3 Lock Up
lPower Flow - Drive 4 (Overdrive)
lPower Flow - Drive4 Lock Up
Each power flow is described in the following sections.
Table 5.1 details the engaged elements versus the gear selected for all transmission selections.
Gear State
Park and Neutral
Reverse
Manual 1
Drive 1
Drive 2 and Manual 2
Drive 3 and Manual 3
Drive 3 Lock Up and
Manual 3 Lock Up
Drive 4 Overdrive
Drive 4 Lock UpC1
-
-
-
-
-
X
X
X
XC2
-
-
X
X
X
X
X
X
XC3
-
X
-
-
-
-
-
-
-C4
-
-
X
-
X
X
X
-
-B1
-
-
-
-
X
-
-
-
-B2
X
X
X
-
-
-
-
-
-1-2
OWC
-
-
-
X
-
-
-
-
-3-4
OWC
-
-
X
X
X
X
X
-
-LU
CLUTCH
-
-
-
-
-
-
X
-
X ELEMENTS ENGAGED Figure 5.1 - Engaged Elements vs Gear Selected
Planetary Gear Set
Page 1025 of 1463

5A-48 AUTOMATIC TRANSMISSION
POWER FLOW - PARK AND NEUTRAL
In Park and Neutral, there is no drive to the planetary gear set. The rear band is applied to eliminate ‘clunk’ on
engagement of the reverse gear, and to improve the low range engagement for 4WD applications. No other clutches
or bands are applied.
In Park the transmission is mechanically locked by engaging a case mounted pawl with teeth on the output shaft ring
gear.
Control
To maintain this arrangement in the steady state solenoids and valves are activated as follows:
lSolenoids S1 and S2 are switched off.
lLine (pump) pressure is applied to the primary regulator valve (PRV) and to the solenoid supply valve.
lThe converter, oil cooler, and lubrication circuits are charged from the primary regulator valve.
lThe line 500 circuit is charged by the solenoid supply valve.
lThe S5 circuit is charged by the variable pressure solenoid (S5).
lLine pressure is prevented from entering the drive circuit by the manual valve.
lThe B1 circuit and all clutch circuits are open to exhaust.
Refer to figure 5.1 and table 5.2.
Table 5.2 - Engaged Elements - Park arid Neutral
Gear State
Park and NeutralC1
-C2
-C3
-C4
-B1
-B2
X1-2
OWC
-3-4
OWC
-LU
CLUTCH
- ELEMENTS ENGAGED
Page 1026 of 1463

AUTOMATIC TRANSMISSION 5A-49
POWER FLOW - REVERSE
In Reverse, transmission drive is via the input shaft and the forward clutch cylinder to the hub of the C3 clutch. The
elements of the transmission function as follows :
lThe C3 clutch is engaged and drives the reverse sun gear in a clock-wise direction.
lThe B2 band is engaged and holds the planetary gear carrier stationary causing the long pinion to rotate anti-
clockwise about its axis on the pinion shaft.
lThe long pinion drives the internal ring fear in the same direction.
lThe internal ring being splined to the output shaft drives it in an anti-clockwise or reverse direction.
Control
To maintain this arrangement in the steady state
solenoids and valves are activated as follows:
lSolenoids S1 and S2 are switched off.
lLine pressure is directed through the reverse lockout valve to both the inner and outer apply areas of the rear
servo piston for B2 band application.
lLine pressure feeds the reverse oil circuit via the manual valve.
lReverse oil is routed from the manual valve to the C3 clutch.
lReverse oil is also applied to the spring end of the primary regulator valve to assist the spring and to boost the
line pressure value.
lAll other clutch and band apply circuits are open to exhaust.
Refer to figure 5.2 and table 5.3
Table 5.3 - Engaged Elements - Reverse
Gear State
ReverseC1
-C2
-C3
XC4
-B1
-B2
X1-2
OWC
-3-4
OWC
-LU
CLUTCH
- ELEMENTS ENGAGED
Page 1027 of 1463

5A-50 AUTOMATIC TRANSMISSION
POWER FLOW - MANUAL 1
In Manual 1, transmission drive is via the input shaft
to the forward clutch cylinder. The elements of the
transmission function as follows :
lThe C2 clutch is engaged to drive the forward sun gear, via the 3-4 OWC.
lThe B2 band is engaged to hold the planetary gear carrier stationary.
lThe forward sun gear drives the short pinion anti-clockwise.
lThe short pinion drives the long pinion clockwise.
lThe long pinion rotating about its axis drives the internal ring gear and the output shaft in a clockwise or
forward direction.
lThe C4 clutch provides engine braking through the 3-4 OWC on overrun.
Control
To maintain this arrangement in the steady state solenoids and valves are activated as follows:
lSolenoids S1 and S2 are switched ON.
lThe 1-2,2-3, and 34 shift valves are held in their first gear positions by line 500 pressure.
lDrive (line pressure) oil from the manual valve engages the C2 clutch.
lLo-1st (line pressure) oil is routed through the 1-2 shift valve to the C4 clutch, and to the inner apply area of
the rear servo piston for B2 band application.
Refer to figure 5.3 and table 5.4.
Table 5.4 - Engaged Elements - Manual 1
Gear State
Manual 1C1
-C2
XC3
-C4
XB1
-B2
X1-2
OWC
-3-4
OWC
XLU
CLUTCH
- ELEMENTS ENGAGED