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7-2
PART
7-1
BORG-WARNER AUTOMATIC TRANSMISSION
Section
1
Description and operation
Torque converter
Transmission
Control system
Hydraulic circuits and power flow
2 Diagnosis and testing
Page
7- 2
7-2
7-3
7-4
7-6
7-11
Section
3 In car adjustments
Table of shift speeds
4 Cleaning and inspection
5 Removal and installation
6 Major repair operations
Pare
7-20
7-21
7-25
7-26
7-26
0
DESCRIPTION AND OPERATION
DESCRIPTION AND OPERATION
The automatic transmission con-
sists of a torque converter and a
hydraulically controlled epicycle gear-
box which provides three forward
gears and one reverse.
The torque converter is an "open"
type which means that the drive
through converter is by means of the
hydraulic fluid circulating
therein.
This gives good flexibility in top gear
which can be engaged at low road
speed with
ligh~ t~ottle op~ning.
Economic operation 1s thus achieved.
The automatic transmission has a
planetary gear set consisting of 2 sun
gears, 2 sets of 3 planet pinior;ts con-
tained within 1 planetary earner and
1 ring gear.
The various speed ratios are
obtained by holding or clutching
various combinations of elements of
the planetary train, and this is per-
formed by two bands, two multi disc
clutches, and a one way clutch.
A gear type oil pump driven by
the engine is employed for supplying
the hydraulic control system.
The engines on
vehicles
equipped
with automatic transmission cannot
be started by pushing or towing the
vehicle.
.
A selector lever may be mounted
on the steering column or on the
floor, the range chosen showing in
the quadrant located above the steer-
ing wheel centre or on the floor
console.
The transmission has six positions
on the selector quadrant and allows
for fully automatic or manually con-
trolled gear
changes.
'P'- (Park)
'R'- (Reverse)
'N' - (Neutral)
FIG. 1 - CRUIS-0-MA TIC
'D' - (Normal Drive Position) -
Car starts in first gear and automatic-
ally shifts to second and third gears.
'2' -
Second gear -
Car starts
and remains in second gear.
'1' - First gear - Car starts and
remains in first gear.
When a shift to '1' is made from 'D'
or '2' with throttle closed the car will
remain in second gear until approxi-
mately
17
mph before shifting to low
gear.
A part throttle downshift has been
incorporated in this transmission to
make it sensitive to torque demand.
TOWING
Important. Should it
be
neces-
sary to tow a vehicle fitted with an
Automatic Transmission, the drive
shaft must be disconnected or the
rear end of the car suspended, other-
wise subsequent failure of the trans-
mission will occur.
TORQUE CONVERTER
The drive from the engine to the
transmission is by means of a three
element hydrokinetic torque conver-
ter which provides an infinitely vari-
able torque multiplication between
2: 1,
.
when starting from rest or
during maximum acceleration, and
1:1, when the engine and transmis-
sion input shaft speeds are approxi-
mately the same. Under the latter
condition the torque converter per-
forms the same function as a fluid
flywheel.
The three elements in the torque
converter are an impeller driven by
the engine and a turbine or rotor
attached to the transmission input
shaft, as in a fluid flywheel, plus a
stator mounted on a sprag
type
one-
way clutch between the impeller and
the
turbine.
The stator can only
revolve in the same direction as the
impeller.
When starting from rest only the
impeller revolves and fluid is thrown
outwards by centrifugal force through
the impeller vanes and is directed
into the turbine thus causing the
turbine to rotate
as
well
(see Fig.
3).
The fluid passes through the turbine
vanes and is directed backwards into
the stator which remains stationarv as
it cannot revolve in the reverse direc-
tion against the one-way clutch. The
direction of the fluid passing through
the stator vanes is changed and on
DEPRESS
KNOB
TO SHIFT
FIG.
2 - Floor Shift Typical
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