26
EXHAUST SYSTEM
Exhaust Gas Recirculation (EGR)
Exh
a
u
st gas
r
ec
ircul
a
t
io
n i
s
designed
to r
ed
uc
e
the
nitri
c oxide e
mission
(NO
x )
in
a
particul
a
r
l
oad
range
of the engine.
Construct
i
on:
The
dev
i
ce co
nsists
of
a
diaphragm contro
l
va
lv
e
(A),
exhaust gas
(8) with
filte
r
(C) and
a
v
ac
uum
contro
l
(D)
Operation
In
th
e
part-load
ran
ge
the
cont
rol
va
lv
e
diaphragm
is
lift
ed by
the vacuum
in
the control lin
e
.
T
he
va
lve opens
and fresh
a
ir is mixed wi
t
h
a
fraction
of the
ex
haust ga
s.
Th
is contro
ll
ed
"pollution"
r
e
duc
es
the
nitric-oxide
concentration
(NO
x
)
in the exhaust
gas.
The funct
i
o
n
o
f
t
h
e
EGR
system
mu
s
t
be
t
ested
every 30,000
miles.
A
cou
nting
mech
a
nism is
fitted
behind the speedo
m
eter
which
ligh
ts
a
warning
l
amp
m
a
rk
ed
wh
e
n
the
30,000 mile limit has
been
r
eached.
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