1997 MERCEDES-BENZ ML320 brake

Center Multi-Disc Brake (B3)
Freewheel F2
Front Multi-Disc Clutch (K1)
Front Planetary Gear Set
The input shaft (1) drives the internal gear (V4). In the drive mode the sun gear (V1) is supported via the locked
freewheel (f1) and in overrun mode in the housing via the engaged front multi-disc brake (B1). The planet gears
(V2) roll over the fixed sun gear (V1) and provide an increase in torque between the internal gear (V4) and the
planet carrier (V3). The planet carrier (V3) moves at reduced speed in the direction of engine rotation.
Rear Planetary Gear Set
The center multi-disc clutch (K2) is engaged and transmits the input speed of the input shaft (1) to the planet
carrier (H3) via the hollow gear (M4). The internal gear (H4) turns at a reduced speed because of its mechanical
connection to the front planet carrier (V3). The planet gears (H2) turn between the ring gear (H4) and the sun
gear (H1). The sun gear (H1) moves at increased speed in the direction of engine rotation.
Center Planetary Gear Set
The hollow gear (M4) rotates at input speed due to the engaged center multi-disc clutch (K2). The rear multi-
disc clutch (K3) transmits a higher speed to the sun gear (M1) due to the connection to the sun gear (H1). The
planet gears (M2) turn between the ring gear (M4) and the sun gear (M1). The speed of the planet carrier (M3)
and the output shaft connected to the planet carrier (5) lies between that of the ring gear (M4) and the sun gear
(M1). This provides a step-up ratio.
Torque Converter, Location/Task/Design/Function

See TORQUE CONVERTER, LOCATION/TASK/DESIGN/FUNCTION
.
Planetary Gear Set, Location/Task/Design/Function

See PLANETARY GEAR SET, LOCATION/TASK/DESIGN/FUNCTION
. .
Multiple-Disc Brake, Location/Task/Design/Function

See MULTIPLE
-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION.
Multi-Plate Clutch, Location/Task/Design/Function

See MULTI
-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION.
Power Flow In Reverse, Function (Without Touch Shift)

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Saturday, October 02, 2010 3:15:28 PMPage 221 © 2006 Mitchell Repair Information Company, LLC.

Torque from the torque converter is increased via the propeller shaft (1) and all three planetary gearsets and
transferred with reversed direction of rotation to the output shaft (5). See Fig. 129
.
The following are not engaged:
Rear Multi-Disk Brake (B2)
Freewheel F2
Front Multi-Disk Clutch (K1)
Front Planetary Gear Set.
The input shaft (1) drive the internal gear (V4). In drive mode the sun gear (V1) is supported via the locked
freewheel (F1) and in overrun mode in the housing via the engaged front multi-disk brake (B1). The planet
gears (V2) roll over the fixed sun gear (V1) and provide an increase in torque between the internal gear (V4)
and the planet carrier (V3). The planet carrier (V3) moves at reduced speed in the direction of engine rotation.
Rear Planetary Gear Set.
The planet carrier (H3) is held securely in the housing due to the engaged center multi-disk brake (B3). The
internal gear (H4) turns at a reduced speed because of its mechanical connection to the front planet carrier (V3).
The planet gears (H2) turn between the ring gear (H4) and the sun gear (H1). The direction is reversed due to
the securely held planet carrier (H3) so that the sun gear (H1) rotates in the opposite direction to the engine.
Center Planetary Gear Set.
The hollow gear (M4) is held securely in the housing by the center multi-disk brake (B3) via the mechanical
connection to the planet carrier (H3). The sun gear (M1) rotates backwards due to the engaged rear multi-disk
clutch (K3). The planet gears (M2) roll over the fixed internal gear (M4) and provide an increase in torque
between the sun gear (M1) and the planet carrier (M3). The output shaft (5) connected to the planet carrier (M3)
turns at a reduced speed in the opposite direction to the running direction of the engine.
Torque Converter, Location/Task/Design/Function

See TORQUE CONVERTER, LOCATION/TASK/DESIGN/FUNCTION
.
Planetary Gear Set, Location/Task/Design/Function

See PLANETARY GEAR SET, LOCATION/TASK/DESIGN/FUNCTION
. .
Multiple-Disc Brake, Location/Task/Design/Function

See MULTIPLE
-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION.
Multi-Plate Clutch, Location/Task/Design/Function

See MULTI
-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION.

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 223 © 2006 Mitchell Repair Information Company, LLC.

Shifting 2nd gear with program selection "W" or "C" (depending on the production period).
Function
Start engine -
The working pressure (p-A) is formed, reaches via the holding pressure 2-3 shift valve, the command valve 2-3
and ball valve (33a) to the rear multi-disc clutch (K3) and via the command valve 3-4 (31c) to the end face of
the shift pressure 3-4 (29c) shift valve. The 3-4 shift pressure shift valve (29c) is moved against the force of the
spring towards the right. At the same time the 3-4 solenoid valve (Y3/6y4) is energized.
The ECT control unit (N15/3) monitors the engagement process via the reduced speed of the drive shaft as the
frictional connection of the rear multi-disc brake increases. When the speed drops to the specified level, the
ECT control module (N15/3) shuts off the power to the 3-4 shift solenoid valve (Y3/6y4). The spring chamber
of the shift valve B2 (26) is depressurized and switches downward. As a result the line to the opposed surface of
the rear multi-disc brake piston (B2b) is connected to the pressure maintaining valve (32). The pressure on the
opposed surface of the rear multi-disc brake piston (B2b) reduces to a residual pressure.
The 3-4 command valve (31c) moves to the left. The working pressure (p-A) reaches via the holding pressure
shift valve 3-4 (28c) and the command valve 3-4 (31c) to the piston of the rear multi-disc brake (B2a).
The activation sequence is complete; 1st gear is engaged (See Fig. 130
.
As a result shift valve pressure (p-SV) reaches the spring chamber of the shift valve B2 (26) and the end face of
the command valve 3-4 (31c).
The shift valve B2 (26) is held in the upper position and the 3-4 command valve (31c) switches towards the
right.
The working pressure (p-a) is replaced by the shift valve pressure (p-SV) at the end face of the shift pressure 3-
4 shift valve (See Fig. 131
).
Move Selector Lever From "N" To "D"
The selector lever (52) opens the shift pressure (p-S) feed connection from the ball valve (33b) with the shift
valve B2 (26). In the upper position of the shift valve B2 (26) shift pressure (p-S) reaches behind (p-S) the
piston of the multi-disc brake (B2a) and simultaneously to the opposed surface of the rear multi-disc brake
piston (B2b).
The rear multi-disc brake begins to close. See Fig. 132
.
The pressure on the opposed surface of the piston of the rear multi-disc brake (B2b) causes a gentle engagement
of the rear multi-disc brake.
Move Selector Lever From "N" To "R"
The selector valve (52) opens the connection of the feed of shift pressure (p-S) with the center multi-disc brake

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Saturday, October 02, 2010 3:15:28 PMPage 229 © 2006 Mitchell Repair Information Company, LLC.

(B3). The further sequence of the switch-on process is as when engaging the rear multi-disc brake.
Residual Pressure
To avoid air getting into the hydraulic system, which causes a deterioration in shift quality, the line system
remains filled with oil in steady-state operation of the automatic transmission.
Function Of Shift From 1 To 2

See SHIFT FROM 1 TO 2, FUNCTION
.
Shift From 1st To 2nd, Function
NOTE: No mating surface on the piston of the center multi-disc brake (B3).

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Saturday, October 02, 2010 3:15:28 PMPage 230 © 2006 Mitchell Repair Information Company, LLC.

Fig. 135: Shift From 1st To 2nd, Function (Second Gear Engaged)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Aim
Engage front multiple-disc clutch (K1), disengage front multiple-disc brake (B1).
Operation
1st Gear Engaged
The end face of the 1-2/4-5 command valve (31a) is kept depressurized via the 1-2 and 4-5 shift solenoid valve
(Y3/6y3). Via the 1-2/4-5 holding pressure shift valve (28a), working pressure (p-A) is applied to the front
multiple-disc clutch (K1) is depressurized. See Fig. 133
.
Shift Phase
Via the 1-2 and 4-5 shift solenoid valve (Y3/6y3), the shift valve pressure (p-SV) is directed onto the end face
of the command valve 1-2/4-5 (31a). See Fig. 134
. The 1-2/4-5 command valve (31a) is displaced and the shift
pressure (p-S) coming from the 1-2/4-5 shift pressure shift valve (29a) via the 1-2/4-5 command valve (31a) is
directed to the front multiple-disc clutch (K1). At the same time the front multiple-disc brake (B1) is subjected
to overlap pressure from the 1-2/4-5 overlap regulating valve (30a).
The B1 pressure acting on the end face of the 1-2/4-5 shift pressure shift valve (29a) is superseded by the
working pressure (p-A). The increasing shift pressure (p-S) at the front multiple-disc clutch (K1) acts on the
annular area of the 1-2/4-5 overlap regulating valve (30a). With an appropriate pressure level at the 1-2/4-5
holding pressure shift valve (28a) this valve switches over.
2nd Gear Engaged
After the gear change is complete, the pressure on the end face of the 12-/4-5 command valve (31a) is reduced
via the 1-2 and 4-5 shift solenoid valve (Y3/6y3) and the command value is pushed back into its original
position. See Fig. 135. Via the 1-2/4-5 holding pressure shift valve (28a) working pressure (p-A) now reaches
the front multiple-disc clutch (K1) via the 1-2/4-5 command valve (31a).
The front multiple-disc brake (B1) is disengaged (depressurized). The spring in the 1-2/4-5 shift pressure shift
valve (29a) pushes this into its original position.
Operating Pressure, Function

See OPERATING PRESSURE, FUNCTION
.
Shift Pressure, Function

See SHIFT PRESSURE, FUNCTION
.
Modulating Pressure, Function

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Saturday, October 02, 2010 3:15:29 PMPage 235 © 2006 Mitchell Repair Information Company, LLC.

Upshift/Downshift Solenoid Valve, Location/Design/Task/Function

See UPSHIFT/DOWNSHIFT SOLENOID VALVE, LOCATION/TASK/DESIGN/FUNCTION
.
Location/Task/Design/Function Of PWM Solenoid Valve, Torque Converter Lockup Clutch

See LOCATION/TASK/DESIGN/FUNCTION OF PWM SOLENOID VALVE, TORQUE
CONVERTER LOCKUP CLUTCH.
Modulating Pressure Regulating Solenoid Valve, Location/Task/Design/Function

See MODULATING PRESSURE REGULATING SOLENOID VALVE,
LOCATION/TASK/DESIGN/FUNCTION.
Shift Pressure Regulating Solenoid Valve, Location/Task/Design/Function

See SHIFT PRESSURE REGULATING SOLENOID VALVE,
LOCATION/TASK/DESIGN/FUNCTION.
Operating Pressure, Function
The working pressure supplies pressure to the hydraulic control and transmission elements. The working
pressure is the highest hydraulic pressure in the entire hydraulic system. The working pressure is regulated at
the working pressure regulating valve in relation to the load and gear. All other pressures required for
transmission control are diverted from the working pressure.
Working Pressure Regulating Valve, Location/Task/Function

See WORKING PRESSURE REGULATING VALVE, LOCATION/TASK/FUNCTION
.
Upshift/Downshift Solenoid Valve, Location/Task/Design/Function

See UPSHIFT/DOWNSHIFT SOLENOID VALVE, LOCATION/TASK/DESIGN/FUNCTION
.
Shift Pressure Control Solenoid Valve, Location/Task/Design/Function

See SHIFT PRESSURE REGULATING SOLENOID VALVE,
LOCATION/TASK/DESIGN/FUNCTION.
Multiple-Disc Brake, Location/Task/Design/Function

See MULTIPLE
-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION.
Multiplate Clutch, Location/Task/Design/Function

See MULTI
-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION.

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:29 PMPage 237 © 2006 Mitchell Repair Information Company, LLC.

Shift Pressure Control Solenoid Valve, Location/Task/Design/Function

See SHIFT PRESSURE REGULATING VALVE, LOCATION/TASK/FUNCTION
.
Multiple-Disc Brake, Location/Task/Design/Function

See MULTIPLE
-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION.
Multiplate Clutch, Location/Task/Design/Function

See MULTI
-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION.
Holding Pressure Shift Valve, Location/Task/Function

See HOLDING PRESSURE SHIFT VALVE, LOCATION/TASK/FUNCTION
.
Shift Pressure Shift Valve, Location/Task/Function

See SHIFT PRESSURE SHIFT VALVE, LOCATION/TASK/FUNCTION
.
Overlap Regulating Valve, Location/Task/Function

See OVERLAP REGULATING VALVE, LOCATION/TASK/FUNCTION
.
Location/Task/Function Of Command Valve

See ELOCATION/TASK/FUNCTION OF COMMAND VALVE
.
Selector Valve, Location/Task

See SELECTOR VALVE, LOCATION/TASK
.
Location/Task/Design/Function Of Oil Pump

See LOCATION/TASK/DESIGN/FUNCTION OF OIL PUMP
.
Shift Pressure, Function
Operation
The shift pressure is determined by the shift pressure regulating solenoid valve (Y3/6y2) and the shift pressure
regulating valve.
The shift pressure:
Regulates the pressure in the activating shift element during the shift phase.
Determines together with the modulating pressure the pressure reduction at the deactivating shift element

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Saturday, October 02, 2010 3:15:29 PMPage 239 © 2006 Mitchell Repair Information Company, LLC.

as regulated by the overlap regulating valve.
Initializes 2nd gear in limp-home mode.
Shift Pressure Regulating Solenoid Valve, Location/Task/Design/Function

See SHIFT PRESSURE REGULATING SOLENOID VALVE,
LOCATION/TASK/DESIGN/FUNCTION.
Shift Pressure Regulating Valve, Location/Task/Function

See SHIFT PRESSURE REGULATING VALVE, LOCATION/TASK/FUNCTION
.
Overlap Regulating Valve, Location/Task/Function

See OVERLAP REGULATING VALVE, LOCATION/TASK/FUNCTION
.
Upshift/Downshift Solenoid Valve, Location/Task/Design/Function

See UPSHIFT/DOWNSHIFT SOLENOID VALVE, LOCATION/TASK/DESIGN/FUNCTION
.
Modulating Pressure Regulating Solenoid Valve, Location/Task/Design/Function

See MODULATING PRESSURE REGULATING SOLENOID VALVE,
LOCATION/TASK/DESIGN/FUNCTION.
Location/Task/Design/Function Of PWM Solenoid Valve, Torque Converter Lockup Clutch

See LOCATION/TASK/DESIGN/FUNCTION OF PWM SOLENOID VALVE, TORQUE
CONVERTER LOCKUP CLUTCH.
Multiple-Disc Brake, Location/Task/Design/Function

See NMULTIPLE
-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION.
Multiplate Clutch, Location/Task/Design/Function

See MULTI
-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION.
Holding Pressure Shift Valve, Location/Design/Function

See HOLDING PRESSURE SHIFT VALVE, LOCATION/TASK/FUNCTION
.
Shift Pressure Shift Valve, Location/Design/Function

See SHIFT PRESSURE SHIFT VALVE, LOCATION/TASK/FUNCTION
.
Command Valve, Location/Design/Function

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:29 PMPage 240 © 2006 Mitchell Repair Information Company, LLC.