722.9 Automatic Transmission

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722.9 Automatic Transmission

(2)

Objectives

? To know the advantages and Features of the

722.9 transmission

? To identify new components

? To understand maintenance concerns

? To know location / function of major components

? To explain shift members

(3)

Features 722.9

h Electronically controlled 7-speed

h Seven forward and two reverse gears

h Fully integrated transmission control unit (Flash capable) h Torque converter operates in open or slip mode in all seven

forward gears

h Gear ratios are achieved with four multi disc brakes and three multi disc clutches (no free-wheeling units)

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Advantages

? Improved shift comfort/driving pleasure

q Quicker shifts 0.1 – 2.5 seconds

q 37 to 74 mph times shortened by between 23% and 28% ? Reduce fuel consumption (up to 4%)

? Reduce maintenance cost

h Increased service life and reliability

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Transmission Designation

Transmission 722. 9 01

Version, e.g. matching to the respective engine Sales designation

Automatic transmission for passenger cars

Sales Designation W 7 A 700

Max. input torque in NM Version (internal)

Number of forward gears Hydraulic torque converter

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Transmission Fluid

? The 722.9 transmission requires a newly developed transmission fluid. MB part number A001 989 45 03

q Higher friction constancy

q Higher thermal stability

q Improved temperature behavior

q Lifetime fill

? Can be used in 722.3 / .4 / .5 / .6

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Major Components (7 G

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Major Components Legend

1. Park pawl gear 2. Turbine wheel 3. Stator

4. Impeller

5. Transmission housing ventilation 6. Oil pump

7. B1 multi-disk brake 8. K1 multi-disk clutch 9. Ravigneaux gear set 10. B3 multi-disk brake 11. K2 multi-disk clutch

12a. Front simple planetary gear set 12b. Rear simple planetary gear set

13. BR multi-disk brake 14. K3 multi-disk clutch 15. B2 multi-disk brake

16. Torque converter lockup clutch 17. Torque converter housing

18. Exciter ring for torque measurement 19. Ring magnet for torque measurement 20. Ring magnet for torque measurement 21. Electro hydraulic control unit

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Transmission Housing

• Magnesium housing (lighter weight) requires aluminum bolts any aluminum bolt must be replaced if removed!

• No power tools

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Ravigneaux Gear Set

1. Short planetary gear Advantages of ravigneaux gear set

• Shifting under load

• Production of several gear ratios

• Constant engagement of gearing

• Easier reversal of rotational direction

• High efficiency

• Compact construction

• Combines 2 simple planetary gear sets into one unit

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Multi

-

_-

disk Clutch/Brake

_{disk Clutch/Brake}

• Transferable power of multi-disk clutch increased

• Friction disks of K1, K2 and K3 now have single-sided friction disks

• Cost advantage

• Less installation space required

• Higher load capability

• Lower mass

1. Friction lining on one side of metal carrier A. Metal carrier outer disk

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Fully Integrated Transmission

Control

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Fully Integrated Transmission

Control Legend

11 Plug connection 21b Valve body 21c Intermediate panel 21d Shift housing 31 Float 1 32 Float 2

Y3/8 Electric control module Y3/8n1 Turbine rpm sensor Y3/8n2 Internal rpm sensor Y3/8n3 Output rpm sensor Y3/8n4 Transmission control

unit

Y3/8s1 Selection range sensor

Y3/8y1 Working pressure control solenoid valve Y3/8y2 K1 clutch control solenoid valve

Y3/8y3 K2 clutch control solenoid valve Y3/8y4 K3 clutch control solenoid valve Y3/8y5 B1 brake control solenoid valve Y3/8y6 B2 brake control solenoid valve Y3/8y7 B3 brake control solenoid valve Y3/8y8 Torque converter lockup clutch

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Electronic Transmission Control

Unit Inputs

Monitors and shifts transmission based on:

• Vehicle speed

• Vehicle load

• Accelerator position

• Selector lever position

• Electronic selector lever module (N15/5)

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Internal inputs effecting solenoid valves

• Turbine rpm sensor (active)

• Internal rpm sensor (active)

• Output rpm sensor (hall)

• Transmission oil temperature sensor

Electronic Transmission Control

Unit Inputs

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Electronic Transmission Control

Unit

• Mounted directly on the hydraulic control unit

• Married to vehicle

– ETC unit calibrated to hydraulic control unit on flow bench

• Information received over CAN with ME – Engine rpm, coolant temperature,

accelerator position, engine load – ESP signals

– Cruise control signals

• Information received from ETC

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Electronic Transmission Control

Unit Functions

From data received Transmission control unit calculates

• Driver and vehicle specific shift points

• Hydraulic pressures

• Torque converter lockup clutch

• Corrects for atmospheric pressure, shifting and pressure

• Driver actions; accelerator movement, manual touch frequency, longitudinal and lateral

acceleration

• Software can be updated, referred to as flashing, carried out using SDS

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Speed Sensor Locations

Y3/8n1 Turbine rpm sensor 1. Ring magnet

• Turbine speed sensor monitors rotational speed of internal

ravigneaux gear

• Internal speed sensor measures rotational speed front planetary gear

• Output speed sensor measures transmission output speed park pawl

• Output speed sensor increases reaction time

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Shift Program

Basic shift program can be influenced using selector button on the electronic selector lever control module

• Driver can choose transmission modes, “C” (comfort) or “S” (sport)

• Each mode has different shift strategies

• Transmission mode “S” (firmer faster shift) as opposed to mode “C” engine rpm level raised

• Switch position transmitted by electronic selector module over CAN-C to ETC

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Shift Programs

The adjustment of the shift programs takes place by moving the characteristic dependent on:

• Vehicle payload

• Change in engine load

• Pedal movement

• Slow Unintended downshifts in high vehicle speed range are prevented

• Fast release The up-shift to the next gear is prevented and is only allowed again at low lateral vehicle acceleration

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Shifting Process

• ETC controls solenoid valves electronically

• Valves sit in hydraulic shift plate

• Shift plate implements hydraulic function

• ETC precisely adjusts pressure during shift phase, which leads to increase in shift quality

• Main function of ETC is to evaluate inputs relevant to transmission

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Solenoid Valves

Internal output signal or actuation of control solenoid valves

• Torque converter lockup clutch valve (Y3/8y8) normally closed in default no pressure

• Working pressure valve (Y3/8y1) normally open in default allows pressure

• K2 clutch valve (Y3/8y3)

normally open in default allows pressure

• B2 brake valve (Y3/8y6)

normally closed in default no

Y3/8y8 – Torque converter lockup clutch valve Y3/8y1 – Working pressure valve

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Solenoid Valves

Internal output signal or actuation of control solenoid valves

normally closed in default no pressure

Y3/8y2 – K1 clutch valve Y3/8y5 – B1 brake valve Y3/8y7 – B3 brake valve Y3/8y4 – K3 clutch valve

722.9 Automatic Transmission