Komatsu PC210-8, Shop Manual

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UEN00100-00 10 Structure, function and maintenance standard
26
PC210, 230, 240-8
Pressure compensation valve 1
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
4. Piston
5. Spring
6. LS shuttle valve
Function
q
Pressure compensation valve works as the
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.
q
As principle, port (C) and spring chamber (E)
are not interconnected in an integrated pres-
sure compensation valve.
q
If high peak pressure is generated at port (C),
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.