8. Automatic transmission
At the moment of a troganiye from a place automatic transmission (AT) acts as ordinary coupling, and during movement performs work on gear shifting. On everything models considered in the real Management are established to series 722.6 AT (see. Specifications).
The AT main hubs are: torque converter (hydrotransformer), planetary reducer and hydraulic or electronic control unit. Hydrodriving disk brakes and disk coupling are applied to transition to other transfer relation in a planetary reducer.
Design of typical AT
The torque converter on the functions corresponds to hydraulic coupling. Its task includes coupling implementation at a troganiye from a place and gear shifting.
The control system of transmission (known also as electronic system of synchronous switching) is the component of the modified control system of the engine established only on model from AT. The control system can work in a special emergency (safe) operation with a limited range of switchings to which passes at detection of any malfunction (the relevant information is displayed the multipurpose display). Switching in emergency operation allows to drive away the car under the own steam on car repair shop for performance of detailed diagnostics and necessary regenerative repair. On the basis of the analysis of the data arriving from various information sensors (not necessarily directly related to functioning actually transmissions), the module of management chooses as transmission (TCM/ETC) optimum from the point of view of profitability, smoothness of switchings and so forth a mode of functioning of AT. At the certain provision of a butterfly valve of TCM can give out command for the blocking of the hydrotransformer leading to restriction of switchings of AT by a range only of the 4th and 5th transfers that promotes considerable reduction of fuel consumption.
The unique procedure of service of AT which performance should be made on a regular basis, check of level of the working liquid (ATF) which order of performance is stated in Head the Current leaving and service is. Need for regular replacement of ATF is absent.
Near a radiator of system of cooling of the engine ATF cooler is established.
On the basis of the data arriving from gas traditionally established under a pedal of the sensor switch of activation of the mode kickdown, TCM carries out transmission switching on adjacent being used at the moment transfer at complete squeezing of a pedal that allows to raise essentially dynamic characteristics of the car, for example during overtaking commission.
There are some 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». On model of the last years of release electronic selector modules with function of a consecutive choice of ranges of a mode of movement "D" (1, 2, 3 and 4) when transfer of AT to a mode of restriction of ranges of switchings (4, 3, 2 and 1) is carried out by lateral otzhimaniye of the lever (D +/D-) (see started to be established. Section Start of motion and switching of automatic transmission).
Thanks to use of the special N/R sensor switch start of the engine can be carried out only when the lever of the AT selector is in the situation "R" or "N" that allows to prevent a casual troganiye of the car in start attempt.
In the present chapter the general procedures of service AT lying within qualification of the average amateur mechanic are considered only most. More detailed information on a design, principles of functioning and service of AT of a series 722.6 can be found in the Managements 179 («Automatic transmissions of modern cars») and 187 («S-class W-203 Mercedes») ARUS publishing houses.