42
ATF supply
The supply of ATF to the eight-speed automatic gearbox 0D7 is
ensured by two pumps: a mechanically driven ATF pump and the
electrically driven auxiliary hydraulic pump 1 for gear oil V475.
Both pumps draw in the ATF via the ATF intake filter. The auxiliary
hydraulic pump V475 is seated behind the mechatronic module
(refer to page 57). When the vehicle is started, it assists the
mechanically driven ATF pump up to a gearbox input speed of
approximately 500 rpm. During vehicle operation, the mechani-
cally driven ATF pump ensures the supply of ATF.
The mechanically driven ATF pump is driven by the e-machine and/
or by the internal combustion engine via the converter housing.
The internal combustion engine can only provide drive if the
separation clutch K0 is closed. If the ATF pump is running at the
required speed, it is able to provide system pressure without any
need for the auxiliary hydraulic pump.
The hydraulic energy results from the system pressure and the
associated volumetric flow rate. It is the prerequisite for gearbox
operation and allows the gearbox control elements (brakes and
clutches) to be controlled, actuated, lubricated and cooled, and
therefore allows the vehicle to be driven.
Mechanically driven ATF pump
This ATF pump is identical to the twin-stroke vane pump used in
the 0BK gearbox.
For more information about the mechanically driven ATF pump,
refer to page 25 of SSP 457. The mechanically driven ATF pump is
connected to the pump drive hub via a chain drive.
The hub spline engages the spline of the converter housing (refer
to cutaway view on page 38). For the sake of clarity, the chain
drive, drive hub and rotor are shown in red in the diagram.
649_080
ATF pump,
mechanically driven
Sun gear shaft S1/S2
Brake A
Pump drive hub with spline
Impeller shaft
Chain drive
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