OPERATION
The 41TE transaxle provides forward ratios of 2.84,
1.57, 1.00, and 0.69 with torque converter clutch
available in 2nd, direct, or overdrive gear; the Re-
verse ratio is 2.21. The shift lever is conventional
with six positions: P, R, N, OD, 3, and L. When OD
is selected the transaxle shifts normally through all
four speeds with torque converter clutch available in
overdrive; this position is recommended for most
driving. The 3 position is tailored for use in hilly or
mountainous driving. When 3 is selected, the trans-
mission uses only 1st, 2nd, and direct gears with
2nd-direct shift delayed to 40 mph or greater. When
operating in 3 or L positions torque converter clutch
application occurs in direct gear for improved trans-
mission cooling under heavy loads. If high engine
coolant temperature occurs, the torque converter
clutch will also engage in 2nd gear. The L position
provides maximum engine braking for descending
steep grades. Unlike most current transaxles, up-
shifts are provided to 2nd or direct gear at peak en-
gine speeds if the accelerator is depressed. This
provides engine over-speed protection and maximum
performance.
CLUTCH AND GEAR
The transaxle consists of:
² Three multiple disc input clutches
² Two multiple disc grounded clutches
² Four hydraulic accumulators
² Two planetary gear sets
This provides four forward ratios and a reverse ra-
tio. The clutch-apply pistons were designed with cen-
trifugally balanced oil cavities so that quick response
and good control can be achieved at any speed. A
push/pull piston is incorporated for two of the three
input clutches.
CAUTION: Some clutch packs appear similar, but
they are not the same. Do not interchange clutch
components as they might fail.
HYDRAULICS
The hydraulics of the transaxle provide the manual
shift lever select function, main line pressure regula-
tion, and torque converter and cooler flow control.
Oil flow to the friction elements is controlled directly
by four solenoid valves. The hydraulics also include a
unique logic-controlled ``solenoid torque converter
clutch control valve''. This valve locks out the 1st
gear reaction element with the application of 2nd, di-
rect, or overdrive gear elements. It also redirects the
1st gear solenoid output so that it can control torque
converter clutch operation. To regain access to 1st
gear, a special sequence of solenoid commands must
be used to unlock and move the solenoid torque con-
verter clutch control valve. This precludes any appli- cation of the 1st gear reaction element with other
elements applied. It also allows one solenoid to con-
trol two friction elements.
Small, high-rate accumulators are provided in each
controlled friction element circuit. These serve to ab-
sorb the pressure responses, and allow the controls to
read and respond to changes that are occurring.
SOLENOIDS
Since the solenoid valves perform virtually all con-
trol functions, these valves must be extremely dura-
ble and tolerant of normal dirt particles. For that
reason hardened-steel poppet and ball valves are
used. These are free from any close operating clear-
ances, and the solenoids operate the valves directly
without any intermediate element. Direct operation
means that these units must have very high output
so that they can close against the sizeable flow areas
and high line pressures. Fast response is also re-
quired to meet the control requirements. Two of the solenoids are normally-venting and two
are normally-applying; this was done to provide a de-
fault mode of operation. With no electrical power, the
transmission provides 2nd gear in OD, 3,orLshift
lever positions. All other transmission lever positions
will operate normally. The choice of 2nd gear was
made to provide adequate breakaway performance
while still accommodating highway speeds.
SENSORS
There are three pressure switches to identify sole-
noid application and two speed sensors to read input
(torque converter turbine) and output (parking sprag)
speeds. There is also a position switch to indicate the
manual shift lever position. The pressure switches
are incorporated in an assembly with the solenoids.
Engine speed, throttle position, temperature, etc., are
also observed. Some of these signals are read directly
from the engine control sensors; others are read from
a multiplex circuit with the powertrain control mod-
ule.
ELECTRONICS
The 41TE transmission control module is located
underhood in a potted, die-cast aluminum housing
with a sealed, 60-way connector.
ELECTRONIC MODULATED CONVERTER CLUTCH (EMCC)
The EMCC enables the torque converter clutch to
partially engage between 23 to 47 MPH before full
engagement at about 50 MPH and beyond. This fea-
ture is on all vehicles equipped with the 41TE tran-
saxle.
ADAPTIVE CONTROLS
These controls function by reading the input and
output speeds over 140 times a second and respond-
Ä TRANSAXLE 21 - 87
