Operation Manual
BX25, RCK54(P)-23BX, RCK60B-23BX, LA240, BT601, WSM
BACKHOE
(3)
Overload Relief Valve
3TAAAAGNP021A
(2)
(7)
(4)
(\
(6\
~
(3)
~~
(12)
3UBAAABNP018A
• Relief Operation
(5)
, 3UBAAABNP019A
B (4)
Overload relief valve
in
this control valve is a
combination valve combining a relief operation and anti-
cavitation operation .
• Relief Operation
When the control valve
is
in
the neutral position, both
cylinder ports
of
control valve are blocked by the spool.
If
an
external load is imposed on the cylinder, pressure
builds
in
the circuit.
When the pressure exceeds the set level of the
overload relief vale, the relief valve opens and the oil
returns to tank.
In
this way, the hydraulic circuit and
actuator are protected from excessive pressures.
• Anti-cavitation Operation
Overload relief valve also has anti-void function. If a
negative pressure takes place
in
the circuit, the oil is fed
from the tank to eliminate the negative pressure.
(1) Overload Relief Valve (7) Piston Poppet
(2) Control Valve (8) Lock Nut
(3) Housing (9) Adjusting Screw
(4) Check Valve Poppet (10) Pilot Spring
(5) Relief Valve Poppet (11) Pilot Poppet
(6) Piston Spring
(12) Pilot Section
W1023498
[When the actuator
port
pressure is
lower
than the
setting]
The cylinder port HP
is
applied to the seat B
in
the
following
route:
first through the throttle a
of
the piston
poppet (1) built
in
the relief valve poppet (5), second
through the spring chamber A, and then through the
circular clearance between the adjusting screw (9) and
the piston poppet (1). This cylinder port HP works to
open the pilot poppet (2). Because the piston spring (3)
has not reached the set pressure, however, the valve
stays shut.
In
this way the seat remains intact and the
relief valve poppet (5) stays shut.
(1) Piston Poppet
(2) Pilot Poppet
(3)
Piston Spring
(4) Adjusting Screw
(5) Relief Valve Poppet
HP
:High Pressure
LP
:Low
Pressure
A:
Chamber
B:
Seat
a:
Throttle
W1024073
9-M16