Page 15 - Hydra-matic 6 Speed RWD Technician's Guide (October 2005)

P
R
N
–
–
–

couple examples.
rearward direction.
at the optimum time.
-
+
M/S

Figure 8
shift quadrant (Figure 8 & 9).
N
P
R
D
the vehicle has come to a complete stop.

and a hydraulic pressurization and control system.
additional torque multiplication when required.
Park position enables the engine to be started while
to the transmission. It also hydraulically provides
locked to the case through the parking pawl and rear
“Park” position. Since the output shaft is mechanically
and is accomplished through the use of a Transmission
stator assembly. The torque converter acts as a fluid
internal gear, Park position should not be selected until
coupling to smoothly transmit power from the engine
Control Module (TCM) located within the transmission.
pressure plate, when applied, provides a mechanical
ratios and reverse. Changing gear ratios is fully automatic
consists primarily of a four-element torque converter,
transmission that features clutch to clutch shifting. It
The Hydra-matic 6 Speed RWD is a fully automatic,
six speed, rear-wheel drive, electronically-controlled
inputs and uses this information to shift the transmission
The TCM receives and monitors various electronic sensor
two planetary gear sets, friction and mechanical clutches
brake should be used in addition to the transmission
preventing the vehicle from rolling either forward or
“direct drive” coupling of the engine to the transmission.
backward. For safety reasons, the vehicle’s parking
The planetary gear sets provide the six forward gear
The
Reverse enables the vehicle to be operated in a
operate without driving the vehicle. If necessary, this
may be four to seven different positions shown on the
Neutral position enables the engine to start and
The transmission shift quadrants vary by model. There
turbine, a pressure plate splined to the turbine, and a
The following are a
The four-element torque converter contains a pump, a
D
–
D –
M/S
–
selector.
downshift.
GENERAL DESCRIPTION
the vehicle is moving.
EXPLANATION OF GEAR RANGES
between forward gears.
control shift timing.
programmed in the TCM.
The
qualities of the transmission.
a lower gear with the shift selector.
Sport shift pattern programmed in the
seven different gear ratios through the gearsets.
DRIVER SHIFT CONTROL GEAR RANGES
gearsets then transfer torque through the output shaft.
FOLDOUT ➤
configuration allows the driver to manually shift
Drive range allows the transmission to operate in each
TCM controls shift feel
The TCM commands shift solenoids and variable bleed
through the pressure control solenoid. The TCM also
(DSC) version of the selector system (Figure 8). This
conditions for maximum efficiency and fuel economy.
depending on the request that is made by moving the
pump, two control valve bodies, converter housing and
driver may activate the manual function by moving the
automatically upshift from first to 6th, and downshift
from sixth to first, according to the normal shift pattern
The
of five multiple disc clutches. The multiple disc clutches
The friction components used in this transmission consist
fuel efficiency without sacrificing vehicle performance.
controls the apply and release of the torque converter
combine with one mechanical sprag clutch, to deliver
friction components. These friction components (when
applied or released) support the automatic shifting
pressure control solenoids within the transmission to
gear, or higher gear ratio are available for safe passing
The hydraulic system primarily consists of a vane type
clutch which allows the engine to deliver the maximum
position should be selected to restart the engine while
Drive range should be used for all normal driving
of the six forward gear ratios. Downshifts to a lower
to stroke the clutch pistons that apply or release the
case. The pump maintains the working pressures needed
selector lever towards “+” or “-” to cause an upshift or
In the Drive position, the transmission will
The transmission will shift up or down
to 6th, and downshift from 6th to 1st, according to the
TCM or, the
transmission will either automatically upshift from 1st
In the M/S (Manual or Sport) position, the
Some vehicles are equipped with a Driver Shift Control
by depressing the accelerator or by manually selecting
9
TCM).
Figure 9
MANUAL SHIFT GEAR RANGES
P R N D M 2 1
input torque is greater than output torque.
Possible Variations
except that the transmission will not shift above
3rd gear unless the transmission is in a undesir-
(figure 9) can be used for conditions where it
forward gear ratios that automatically change as
for changing forward gear ratios is to provide
and driving on hilly terrain. These ranges are
the performance and economy expected from
slight grades. Upshifts and downshifts are the
end, a gear ratio that develops a lot of torque
ratios. These conditions include towing a trailer
the speed of the vehicle increases. The reason
accomplishes this task by providing a number of
Some vehicles are equipped with a shift quad-
economy becomes the important factor and the
transmission is to allow the engine to be started
transmission will shift into overdrive. At this point
rant that allow manual range selection. For ex-
order to initially start a vehicle moving. Once
the vehicle is in motion, less torque is required
output speed is greater than input speed, and,
vehicles manufactured today. On the performance
ample, manual range and or manual range 2 or 1
Another important function of the automatic
When the vehicle has reached a desired speed,
in order to maintain the vehicle at a certain speed.
may be desirable to control the selection of gear
(through torque multiplication) is required in
4th gear. 1st, 2nd or 3rd manual range can be
component of a vehicle that transfers power
same as in Drive range 1st, 2nd, and 3rd gears,
selected at any vehicle speed but will downshift
3 - Manual 3rd adds more performance for con-
(torque) from the engine to the wheels. It
into the selected gear only if vehicle speed is low
able RPM range, in which case it will shift into
An automatic transmission is the mechanical
also helpful for engine braking when descending
enough not to over-rev the engine (calibrated in
needs.
(calibrated in TCM).
PRINCIPLES OF OPERATION
systems is made easier.
engine (calibrated in TCM).
engine (calibrated in TCM).
from shifting above 1st gear.
matic 6 Speed RWD transmission.
selected (accomplished by the gear sets).
components inside the transmission.
Neutral (N) range has been selected.
vehicle speed is low enough not to over-rev the
sired. Manual 3rd can be selected at any vehicle
speed but will downshift into third gear only if
but will downshift into 1st gear only if vehicle
understanding of these operating principles has
vents the transmission from shifting above 3rd
been attained, diagnosis of these transmission
gested traffic and hilly terrain. It has the same
and run without transferring torque to the wheels.
When an
Also,
theoretical operation of the mechanical, hydraulic
gear for acceleration and engine braking as de-
gear. Thus, Manual 3rd can be used to retain 3rd
and electrical components found in the Hydra-
The following pages describe the
Thus, Manual 1st
vents the transmission from shifting above 2nd
speed but will downshift into 2nd gear only if
starting ratio (1st gear) as Drive range but pre-
transmission are made possible through the
gear for acceleration and engine braking as de-
sired. Manual 2nd can be selected at any vehicle
gear) as Drive range but prevents the transmission
gear. Thus, Manual 2nd can be used to retain 2nd
appropriate time and sequence, these components
Manual 1st can be selected at any vehicle speed
2 - Manual 2nd adds more performance for con-
gear set at a gear ratio consistent with the driver’s
operating the vehicle in a rearward direction is
are either applied or released and operate the
gested traffic and hilly terrain. It has the same
(creeper gear) and engine braking as desired.
can be used to retain 1st gear for heavy towing
starting ratio (1st gear) as Drive range but pre-
The variety of gear ranges in an automatic
vehicle speed is low enough not to over-rev the
interaction of numerous mechanically,
At the
possible whenever Reverse (R) range has been
speed is low enough not to over-rev the engine
This situation occurs whenever Park (P) or
hydraulically and electronically controlled
1 - Manual 1st has the same starting ratio (first
9A