Komatsu ecot3 PC300LC-8 Shop Manual page 150

SEN01994-01
Pressure compensation valve
1. During independent operation and under maximum load pressure
(If the load pressure is higher than other work equipment during a combined operation)
1. Hydraulic pump
2. Valve
3. Shuttle valve
Function
Pressure compensation valve works as the
q
load check valve.
q If the pump pressure (LS pressure) is lower
than the load at port (c), shuttle valve (3) in
pressure compensation valve piston (4) inter-
connects spring chamber (E) and port (C).
q The force of spring (5) operates piston (4) and
valve (2) to the closing direction.
Integrated pressure compensation valve
q High stress may occur when valve (2) collides
with valve chamber seat portion (C) if a high
peak pressure is generated in the actuator cir-
cuit or repetitive peak pressure occurs continu-
ously (example: when using the breaker).
q To prevent this, a pressure compensation
valve with integrated valve (2) and piston (4) is
used.
q With the present machine, this device is
adopted for the bucket valve (cylinder bottom)
and the service valve.
24
10 Structure, function and maintenance standard
4. Piston
5. Spring
6. LS shuttle valve
q As principle, port (C) and spring chamber (E)
are not interconnected in an integrated pres-
sure compensation valve.
If high peak pressure is generated at port (C),
q
valve (7) does not collide with the valve cham-
ber.
q With a bucket valve, etc., port (C) and spring
chamber (E) are designed to interconnect
before valve (7) is seated.
PC300, 350-8