Komatsu Galeo PC800-8 Shop Manual page 219

10 Structure, function and maintenance standard
2. Arm at HOLD
The oil that has flowed through orifice a in valve
(2) is closed by pilot piston (1). At the same
time, the hold pressure at the bottom end of the
arm acts in the bottom direction on ring-shaped
area C (= Area of ød1 – Area of ød2) because
of the difference in the outside diameter d1 of
valve (2) and seat diameter d2. Valve (2) is
closed by the total of this force and the force of
spring (3), so port A and port B are shut off.
PC800, 850-8
SEN00384-02
57