Operation Manual

BX25, RCK54(P)-23BX, RCK60B-23BX, LA240, BT601, WSM
BACKHOE
A
(2) (3)
[When the actuator port pressure is higher than the
setting]
When the cylinder port HP has reached the set
pressure
of the piston spring (5), the pressure oil in the
spring chamber A opens the pilot poppet (4) and flows
through the drain passage into the tank passage. This
lowers the pressure
in the spring chamber A, and the
pressure difference across the throttle
a moves the relief
valve poppet
(1) to the right. Now the seat of the relief
valve poppet
(1) gets open. The pressure oil flows then
from this seat into the tank, and the circuit pressure is
(5) (4)
kept at the pressure level set by the overload relief valve.
3UBAAABNP020A
Relief valve setting pressure
17.20 to 17.69 MPa
Dipperstick 175 to 180
kgf/cm
2
2489 to 2560 psi
13.7 to 14.1 MPa
Swing 140 to 145
kgf/cm
2
1991 to 2062 psi
• Oil temperature: 45 to 55°C
113 to 131°F
(1) Piston Poppet HP :High Pressure
(2) Pilot Poppet
lP :low Pressure
(3) Piston Spring
A: Chamber
(4) Adjusting Screw
a: Throttle
(5) Relief Valve Poppet
W1024163
• Anti-cavitation Operation
This valve, in operation, prevents a condition - so
called cavitation - that arises in the cylinder port
HP
(1 ) (2)
where fluid is not entirely filling out.
That
is, this relief valve is combined an anti-cavitation
functions supplying oil.
The pressure
oil at the tank port
LH opens the check
valve poppet, allowing oil to flow through the tank port to
prevent negative pressure from being generated
in the
cylinder.
(1) Check Valve Poppet
(4) Relief Valve Poppet
(2) Piston Spring
(5) Piston Poppet
(3) Pilot Poppet
W1024467
(5) (4) (3)
3UBAAABNP021 A
9-M17