Activation Of The Engine Brake; Deactivation Of The Engine Brake - Mercedes-Benz OM 471 Introduction Into Service Manual

Design
Shown on engine brake valve, stage 1 (Y624)
1 Coil
2 Valve body
3 Outlet rocker shaft
4 Oil ducts for cylinders 1...3
Y624 Engine brake solenoid valve, stage 1
Function
For a stopped engine the valve body (2) lies under the force of
gravity on its downstop. The control oil passage to the exhaust
rocker arm spindle (3) is open. Since there is no oil pressure
applied at this point in time, no control oil flows in the direction
of the outlet rocker shaft (3).
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Activation of the engine brake

The engine management (MCM) control unit (A4) actuates the
engine brake solenoid valve, stage 1 (Y624) just as soon as the
driver activates the engine brake over the engine brake switch.
The energization of the coil (1) the valve body (2) is presses into
the downstop.
The pressure oil now flows through the again opened pressure oil
passage over the oil duct for cylinders 1...3 (4) contained in the
outlet rocker shaft (3) to the exhaust rocker arms with
hydroelement. The engine brake is activated in this way.
i Introduction of engine OM 471 and exhaust aftertreatment > 09/2011 >
– This printout will not be recorded by the update service. Status: 09 / 2011 –
System components
If the engine is started oil pressure is applied to the valve body (2)
and pushes this against the upper stop. In this way the control oil
passage to the exhaust rocker arm spindle (3) is closed off.
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Deactivation of the engine brake

If the driver sets the engine brake switch back into position 0 or
the engine brake is deactivated, the coil (1) is no longer energized
> the valve body (2) is pushed upwards. No more oil flows over the
control oil passage in the outlet rocker shaft (3). The oil remaining
in the outlet rocker shaft (3) escapes in the ventilation.
i For brake stages 2 and 3 engine brake valve, stage 2 is
actuated.
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