Sectional View Of Secondary Water Retarder; Relief Valve; Valve Block - Mercedes-Benz OM 471 Introduction Into Service Manual

System components

Sectional view of secondary water retarder

in idle mode
5

Valve block

6 Actuator
7 Switching valve
8 Switching valve compression spring
9 Control valve compression spring
10 Control valve
11 Side channel pump
12 Compression spring for sliding rotor
13 Twisted teeth
14 Slide ring seal
15 Retarder shaft
17 Rotor
18 Stator
20 Shutoff pressure line, return
A11 Retarder control (RCM) control unit
Function
i The individual components shown under Design perform the
functions described below.

Relief valve (4)

The relief valve (4) actuates the side channel pump (11) when
requested by the retarder control unit (RCM) (A11).
Valve block (5)
The valve block (5) consists of an actuator (6), a switching valve (7),
a control valve (10), the switching valve compression spring (8) and
the control valve compression spring (9).
If a braking torque is requested, the switching valve (7) directs the
engine coolant into the working chamber. If no braking torque is
requested, the switching valve (7) separates the working chamber
from the coolant circuit. Depending on the pneumatic pressure
applied, the control valve (10) controls the coolant feed into the
working chamber and thus the intensity of the braking effect. In
idle mode, the control valve (10) acts as a check valve and seals the
bypass to the working chamber.
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