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Fav 900
Transmission / Transmission control unit
Transmission control unit functional sequence
A
General
Fav 900 chassis number 23/3001 and up
6.8.2001
1005
000005
A
a
2/4
Capitel
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Transmission control unit functional sequence
Cooled transmission oil is supplied to the high-pressure circuit via two non-return valves alternately.
Hot transmission oil is discharged from the high-pressure circuit via the flush valve (2V5).
The high-pressure circuit incorporates: a variable-displacement pump (2P1) and two
variable-displacement motors (2A1 / 2A2), two non-return valves, two servo-assisted
high-pressure-relief valves (2V3 / 2V4), a flush valve 2V5), a turboclutch pressure-relief valve (4V4 /
Y004), a clutch pressure-relief valve (4V5) and a test connection.
The regulator cylinders of the variable-displacement pump and variable-displacement motors are
actuated by two 4/3-way valves.
The 4/3-way valves are activated mechanically by the actuator shaft.
The actuator shaft is rotated as required by the actuator unit, thereby setting the correct quantity of oil
to be supplied or consumed.
The variable-displacement pump and variable-displacement motors swivel accordingly.
In Emergency mode the actuator shaft is operated manually from the cab.
For further details on the actuator unit (A009), please see the section dealing with electronics.
In Emergency mode the transmission is automatically locked at approx. 30 km/h after the engine has
been started.
If the clutch pedal, handbrake or neutral switch is operated, the high-pressure circuit is depressurised
by means of the two high-pressure-relief valves.
Operation of the turboclutch is controlled via the pressure-relief valve.
Important note on filling the ML 200 transmission with oil:
During normal maintenance work, e.g. for a transmission oil change, the transmission oil should be
added as in a normal change-gear transmission.
If there is no oil in the high-pressure circuit, the transmission must be filtered via an external hydraulic
oil-filling unit.
See Chapter 1080 Reg. G
The transmission oil is also filtered through the connection as it is being added.
If the oil is not topped up, it may result in damage to the variable-displacement pump and
variable-displacement motors if they run dry after starting up.
Electrical / electronic control
The CAN-bus is a data line which connects various components (also called users) to each other. If a
large amount of data is transmitted, the voltage in the CAN-bus (+ and - wires) rises.
In the Favorit 900 chassis number 23/3001 and up data are transmitted via three CAN-bus systems
K-bus
= enhanced control bus
G-bus
= transmission bus
EDC-bus = E letronic D iesel C ontrol
Text-module
The voltage can be checked at the CAN-bus sockets