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c.
Cycling
Valve
(See Figure
3-32).
(a) The valve
is properly
adjusted
when
the
low
pressure
gage on
the
regulator
reads
15
to
17 psi at
1. Cycling
Valve
Control
Arm Adjustment.
the
time
the
valve
shaft
automatically
returns
to
its
normal
position
completing
the
deicing
cycle.
This
(a) Adjustment
for
all possible
variations
in
the
is known as
the
"pop-off"
pressure.
The low pres-
control
arm
assembly
is
accomplished
by
the
ad-
sure gage
on
the
regulator
will show a higher
value
dition
or removal
of laminated
shims
between
the
after
the
valve
completes
the
deicing
cycle.
This
upright
supporting
the
control
arm and
the
angle
higher
value
is
the
set pressure
of
the
regulator.
attaching
the
upright
to
the
valve
mechanism
base.
(b) The valve
is adjusted
by
rotating
a ring on
(b) With
the
valve
shaft
actuated
and locked
in
the
valve
located
directly
below
the top
plate
on
the
the
detent,
the
control
arm
is properly
adjusted
only
working
end of
the
valve.
The
cam
action
of
the
when
the "dog"
which
operates
the
valve
shaft
will:
interior
of
this
ring increases
or decreases
the
"pop-off"
pressure
as
the
ring rotates.
(1) Engage
1/64
to
1/32
of an inch on
the
shaft,
and
then:
(c) To
adjust
the
"pop-off"
pressure
of
the
valve:
(2) Slide
past
the
shaft without
driving
the
shaft
(1)
Remove
the
cotter
pin
locking
the
adjusting
beyond
and out of
the
detent,
ring
to
the
valve
body.
(c) The adjustment
of
the
mechanism
is accom-
(2)
Cycle
the
valve and observe
the
"pop-off"
plished
by loosening
the
fasteners
between
the
pressure
on
the
low
pressure
gage
of
the
regulator,
previously
described
upright
and angle,
then
adding
or removing
laminated
shim
stock.
(3)
Rotate
the
adjusting
ring,
recycle
the
valve
and
again observe
the
"pop-off"
pressure.
(4) From
the
"pop-off"
pressures,
determine
the
direction
to
rotate
the
adjusting
ring
to
increase
or
decrease
the
"pop-off"
pressure.
(5) Set
the
adjusting ring on
the
valve
so
that
the
"pop-off"
pressure
is
from
15-17
psi.
(6)
Relock
the
adjusting
ring
to the
valve
body
with
the
cotter
pin.
LIGHTWEIGHT
AUTOMATIC
(PUMP-DRIVEN)
SURFACE
DEICER
SYSTEM.
-
The
following
description
applies
to
deicer
systems
utilizing
Goodrich control
valves,
but is applicable
also
to
systems
incorporating
Tavco
control
valve
assemblies
with
the
exception
of control
valve
oper-
ation and air
filtering
provisions,
which will be
discussed
separately.
1.
'Pop-Off'
Pressure
Adjusting
Ring
The principle
components
of
the
deicer
system
are:
2. Detent
lightweight
rubber
and
fabric pneumatic
deicer
boots
3. Cotter Pin
cement-bonded
to the
wing
and
empennage
leading
4.
'Dog'
edges;
the two
engine-driven
vacuum
pumps
which
5.
Shim
Location
provide
air pressure
for
deicer
boot
inflation
and
vacuum
for
deicer
boot deflation;
an
electric
timer
Figure
3-32.
Cycling
Valve
forward of
the
instrument
panel
which
actuates
a
solenoid
operated
combination
overboard
-
pressure
If
the
"dog"
engages
too
far on
the
shaft or drives
relief
control valve in each engine
nacelle;
pressure
the
shaft
past
the
detent,
add shims
until
the
mech-
sensitive
shuttle
valves
to
control
the
flow of air
to
anism
is properly
adjusted.
If
the
"dog" does
not
and
from
the
boots; a
three-position
switch
to
con-
cause
the
valve shaft
to
engage
in
the
detent,
remove
trol the
operation
of
the timer
(and
hence
the
deicer
shims
until
the
Valve
shaft
engages
in
the
detent
system);
and
the
necessary
plumbing
and wiring
satisfactorily.
.
components.
(d)
The
valve operating
mechanism
and valve
Normally,
the
engine-driven
vacuum
pumps
apply
should
be
functionally
tested
with
pressure
from
the
vacuum
to the
deicer
boots
at
all
times,
except
when
reservoir
package.
the
boots
are
being
inflated.
When
the
deicer
system
control
switch
is placed
in
either
the
MANUAL
or
2. Cycling Valve Adjustment.
AUTOMATIC
position,
the timer
energizes
the
3-48
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