1/: The control valve reduces oil pressure; the pres-
sure is around 1 bar in the rocker arm shaft. The check
valve (7) is held open by the piston (8) being moved
forward by the spring (9). The oil channels are filled
with oil but the low pressure is not sufficient to raise
the pump piston (5) to its upper position.
The EGR rocker arm (10) has no contact with the
exhaust rocker arm (4). In this situation the exhaust
valves are not affected by the EGR cam lobe.
EGR activation
2/: The control valve raises the oil pressure to system
pressure; the pressure is above 2 bars in the rocker
arm shaft. The piston (8) is moved backwards but the
check valve (7) is held open by the oil flow. The high
pressure is sufficient to lift the pump piston to its upper
position.
When the pump piston (5) is forced to the upper posi-
tion, the clearance between the EGR rocker arm (10)
and the exhaust rocker arm (4) is reduced.
20-0 Engine Information, General
7748841 06-2010 73
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