Mercedes S-Class W-140
1991-1999 of release
Repair and operation of the car
+ Mercedes-Benz cars of the class S (W-140)
+ Operation manual
+ Routine maintenance
+ Cooling systems, heating
+ Power supply system and release
+ Engine electric equipment
+ Gear shifting box
- Automatic transmission
Search of malfunctions - the general information
+ Automatic transmission 722.5
+ Automatic transmission 722.6
+ Brake system
+ Suspension bracket and steering
+ Onboard electric equipment
Automatic transmission, in the course of start-off from the place, performs function of ordinary coupling, and during the movement performs work on gear shifting.
Design of typical ATDesign of typical AT
Section of automatic transmission
The torque converter on the functions corresponds to hydraulic coupling. Its task includes implementation of coupling at start-off from the place and gear shifting.
The control system of transmission (known as electronic system of synchronous switching) is a component of the modified control system of the engine installed only on model with AT.
Scheme of an arrangement of electronic components of a control systemLocation of the AT (N15/3) control unit. In a motive compartment, on the right at a partition
Analyzing information arriving from various sensors (not only the sensors directly related to transmission), the control system chooses optimum from the point of view of profitability, smoothness of the course, etc. a box operating mode. At a certain position of the gate of a throttle the control system can block the hydrotransformer in such a way that only the fourth and fifth transfers will join. It reaches considerable decrease in consumption of fuel.
The only regular procedure of service of a box is check of level of working liquid (see the Section Check of Levels of Liquids, control of leakages of the Head Routine maintenance). Regularly it is not necessary to change transmission liquid.
Near a radiator of the cooling system the cooler of transmission liquid is established.
There is no traditional switch of the kickdown mode. Activation of the mode is carried out directly by a control system of transmission after the information processing arriving from the sensor of provision of a butterfly valve.
There are several operating modes of transmission, each of which can be involved after moving of the selector to one of the following provisions: "P", "R", "N", "D", "1", "2", "3", "4" (address the Head the Operation manual).
The engine can be started only if the selector is in situation "P" or "N". It is made to prevent the movement of the car in start attempt (if the selector is installed in one of other provisions). Analyzing information arriving from sensors, the control system resolves or forbids start of the engine. The locations of various relays are specified in the Head Onboard electric equipment).