Design Of The Rocker Arm; Exhaust Valve Control For A Deactivated Engine Brake - Mercedes-Benz OM 471 Introduction Into Service Manual

As>built configurations
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Design of the rocker arm

1 Exhaust rocker arm
18 Rocker arm roller
19 Adjusting element for adjusting the
valve clearance
20 Oil inlet hole
The valve control of the exhaust side is characterized by the fact
that every cylinder has three rocker arms > one exhaust rocker arm
(1), one exhaust rocker arm with hydroelement (2) and one brake
rocker arm (3).
All rocker arms are fitted with a rocker arm roller (18). Use of
rocker arm rollers (18) means that wear between the respective
actuation cams of the exhaust camshaft (6) and the corresponding
rocker arm is reduced. The noise emission of the valve assembly is
also reduced.

Exhaust valve control for a deactivated engine brake

2 Exhaust rocker arm with hydroelement
3 Brake rocker arm
4 Exhaust rocker arm spindle
6 Exhaust camshaft
7 Outlet valve
21 Piston
22 Check valve
Rotational movement of the camshaft is converted into linear travel by the exhaust cam on
the exhaust camshaft (6) and transferred to the associated exhaust rocker arm on the
exhaust rocker arm spindle (4). The exhaust rocker arms steer the linear travel in turn onto
the respective exhaust valves (7) which are opened and then closed again by the valve
springs.
Because the pistons (21) are pressed by a spring to their lower limit stop when the engine
brake is deactivated, no contact takes place between the brake rocker arms (3) and the
exhaust rocker arms with hydroelement (2) and the brake rocker arms (3) run in idle. This
serves to prevent any unnecessary piston (21) motion and therefore any unnecessary wear.
26
2 Exhaust rocker arm with
hydroelement
18 Rocker arm roller
19 Adjusting element for adjusting the
valve clearance
20 Oil inlet hole
21 Piston
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3 Brake rocker arm
18 Rocker arm roller
23 Adjusting element for engine brake
The exhaust rocker arm (1) and exhaust rocker arm with
hydroelement (2) are each equipped with an adjusting element
for adjusting the valve clearance (19). The clearance between the
brake rocker arm (3) and exhaust rocker arm with hydroelement
(2) is set using the adjusting element for the engine brake (23).
The exhaust rocker arm (1), exhaust rocker arm with
hydroelement (2) and brake rocker arm (3) are mounted rotatable
on the exhaust rocker arm spindle (4).
The exhaust rocker arm spindle (4) is made out of solid material
due to the higher loads in the engine brake system and is fitted
with oil ducts > a lubricating oil duct (15) and two oil ducts for
operation of the engine brake.
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