Installation Instructions
8 HYDRAU
Lie
SYSTEM
B1700·B21
00·B2400
WSM,
11772
Tl,
T3:
Tank Port
(5)
Passage 5
(6)
Spool
(7) Unload Poppet
(8) Plunger
II
Shockless Mechanism
The
control
valve
is
provided
with
a shockless
mechanism. This
is
intended
to
reduce a sudden
change
of
the oil pressure and
flow
when
the
three
point
linkage
system begins
to
going
up
or
stop
going up.
As
a result, operator does
not
feel
the
unpleasant shock.
1.
When
the
three
point
linkage system starts going
up, the spool
(6)
is
located
slightly
at
the
right
from the neutral position. (Fig.
B)
2.
The
oil fed from hydraulic pump
flows
in
passages
3 (3) and 4 (4) by
the
difference
of
the
hole
diameter, and
pushes
the plunger
(8)
to
the
left.
Then
the
passages
4
(4)
and 5
(5)
connect
to
each
other, and
the
oil
between
them
return
to
the
transmission
case
through
the
clearance between
the valve body and the spool
(6)
and
through
the
T3
port.
In
this way,
the
plunger (8) returns
to
the
rightmost position. (
Fig.
Band
C)
3.
As
a result,
the
oil pressure
is
controlled
not
to
rise
suddenly.
The
shock
at
the start
of
lifting
is
thus
reduced.
4.
When the spool (6) comes close
to
the
neutral
position by the motions
of
feedback linkage,
the
oil pressure gradually drops by
the
slit provided in
the spool
(6).
Therefore the shock
at
the
stop
of
lifting
is
reduced. (Fig.
D)
c p
B
P:
Pump Port
C:
Cylinder Port
S:
Slit
(1)
Passage 1
(2)
Passage 2
(3)
Passage 3
C
(4) Passage 4
C P
A
Tl
D
c
B193F808
Tl
E8-M5