MERCEDES-BENZ ML430 1997 Complete Repair Manual

Fig. 129: Power Flow In Reverse, Function
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Principle Of Power Transmission In Reverse Gear.

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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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
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Location/Task/Design/Function Of Freewheel

See LOCATION/TASK/DESIGN/FUNCTION OF FREEWHEEL
.
Function Of Gear Shift (With Touch Shift)
Transmission with touch shift.
On transmission 722.6 the electrohydraulic control unit converts the electric signals going out from the
electronic transmission control (EGS) into hydraulic signals.
Faults occurring in the ETC control unit (N15/3) are handled by the limp-home system. The limp-home system
is designed so that the driver can reach a Service Operation even under extreme conditions.
Selector lever position "P", "R", "N" and "D" are transmitted by the electronic selector lever module control unit
(N15/5) on the Controller Area Network bus class C (engine compartment) (CAN-C) and in parallel to this by
means of a shift rod to the range selector lever at the transmission end. By touching or holding the selector lever
towards "+" or "-" the shift range is pre-selected and displayed in the instrument cluster (A1) until an upshift of
transmission 722.6 is possible.
Function Of Gear Change

See FUNCTION OF GEAR CHANGE
.
Emergency Default Mode, Function

See LIMP
-HOME MODE, FUNCTION.
Function Of Manual Drive Mode Selection

Oil Level Control, Function

See OIL LEVEL CONTROL, FUNCTION
.
Torque Converter Lockup Clutch Control, Function

See FUNCTION OF TORQUE CONVERTER LOCKUP CLUTCH CONTROL
.
Function Of Gear Shift (Without Touch Shift)
On transmission 722.6 the electrohydraulic control unit converts the electric signals going out from the
electronic transmission control (EGS) into hydraulic signals.
Faults occurring in the ETC control unit (N15/3) are handled by the limp-home system. The limp-home system
is designed so that the driver can reach a Service Operation even under extreme conditions.
Selector lever position "P", "R", "N" and "D" are transmitted by the electronic selector lever module control unit

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 224 © 2006 Mitchell Repair Information Company, LLC.

(N15/5) on the Controller Area Network bus class C (engine compartment) (CAN-C) and in parallel to this by
means of a shift rod to the range selector lever at the transmission end. By touching or holding the selector lever
towards "+" or "-" the shift range is pre-selected and displayed in the instrument cluster (A1) until an upshift of
transmission 722.6 is possible.
Function Of Gear Change

See FUNCTION OF GEAR CHANGE
.
Emergency Default Mode, Function

See LIMP
-HOME MODE, FUNCTION.
Oil Level Control, Function

See OIL LEVEL CONTROL, FUNCTION
.
Torque Converter Lockup Clutch Control, Function

See FUNCTION OF TORQUE CONVERTER LOCKUP CLUTCH CONTROL
.
Function Of Gear Change
Operation
Every gear change is triggered by the electronic transmission control (ECT). Each shift sequence is assigned a
control block. Each of these contains one overlap regulating valve, one holding pressure shift valve, one shift
pressure shift valve, one common command valve and one electromagnetically actuated switchover valve
(upshift/downshift solenoid valve).
Actuation of the solenoid valve switches over from stationary mode to the shift phase.
When the gear change is complete the solenoid valves are no longer actuated as the different gears are subject to
a self-hold function in stationary mode.
Shifting "N" To "D" (1st Gear), Function

See SHIFTING N TO D (1ST GEAR), FUNCTION
.
Shifting N To D (1st Gear), Function
Transmission 722.6 As Of 1.7.96

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Fig. 130: Shifting N To D (1st Gear), Function (1st Gear Engaged)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Fig. 131: Shifting N To D (1st Gear), Function (Engine Started)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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Fig. 132: Shifting N To D (1st Gear), Function (Activation Sequence Active)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Initial Situation:
Selector lever in position "N" or "P".
Engine off.
No pressure in hydraulic system.
All valves in the shift plate in neutral position.
Aim
To en
gage 1st gear with program "S" selected.

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1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
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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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(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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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 231 © 2006 Mitchell Repair Information Company, LLC.