7.6 Operation of tilt lock valve
7.6 Operation of tilt lock valve
The tilt—lock valves are intended to prevent vibrations of the mast due to possible
The tilt—lock valves are intended to prevent vibrations of the mast due to possible
creation of internal negative pressure in the tilt cylinder and also to
creation of internal negative pressure in the tilt cylinder and also to
avoid a danger of the
avoid a danger of the
mast tilting due to accidental lever action when the engine is at rest.On the conventional
mast tilting due to accidental lever action when the engine is at rest.On the conventional
model
model
,even if the
,even if the
engin
engin
e is
e is
kept at
kept at
rest,
rest,
the mast can
the mast can
be tilted forward by actuating the
be tilted forward by actuating the
tiltlever.but this newly adopted tilt—lock valves does not allow the
tiltlever.but this newly adopted tilt—lock valves does not allow the
mast to tilt forward as
mast to tilt forward as
far as the engine is at rest,even if the tilt lever is pushed with the full load.Refer to fig.7-9
far as the engine is at rest,even if the tilt lever is pushed with the full load.Refer to fig.7-9
for the construction of the tilt—lock valve.
for the construction of the tilt—lock valve.
The port “A” side of the plunger housing is led to the front side of the tilt
The port “A” side of the plunger housing is led to the front side of the tilt
cylinder,and the port “B” side to its rear side.When the tilt lever is pulled(plunger
cylinder,and the port “B” side to its rear side.When the tilt lever is pulled(plunger
drawn out),the oil from the pump flows into the port “A” while the port “B” side oil
drawn out),the oil from the pump flows into the port “A” while the port “B” side oil
returns to the tank,due to which the mast is
returns to the tank,due to which the mast is
tilted backwa
tilted backwa
rd by the
rd by the
tilt cylinde
tilt cylinde
rs.
rs.
When the tilt lever is pushed (plunger pressed),the oil from the pump flows into the
When the tilt lever is pushed (plunger pressed),the oil from the pump flows into the
port “B”.But the port “A” side oil does not return to the tank unless the poppet
port “B”.But the port “A” side oil does not return to the tank unless the poppet
installed in the plunger is moved,nor does the mast tilt forward.Hence,while the engine is
installed in the plunger is moved,nor does the mast tilt forward.Hence,while the engine is
being shut down,the mast never tilts forward nor does the internal pressure in the tilt
being shut down,the mast never tilts forward nor does the internal pressure in the tilt
cylinders get negative.
cylinders get negative.
Fig.7.9 Tilt lock valve
Fig.7.9 Tilt lock valve
T
T
:
:
T
T
o
o
t
t
a
a
n
n
k
k
P
P
:
:
T
T
o
o
o
o
i
i
l
l
p
p
u
u
m
m
p
p
A
A
、
、
B
B
:
:
T
T
o
o
t
t
i
i
l
l
t
t
c
c
y
y
l
l
i
i
n
n
d
d
e
e
r
r
Tilt cylinder
Tilt cylinder
Spring
Spring
Poppet
Poppet
Plunger
Plunger
-90-
-90-
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