Komatsu Galeo PC800-8 Shop Manual page 155

10 Structure, function and maintenance standard
Operation
• The output pressure of the EPC valve is applied
to the piston chamber to push piston (6). Piston
(6) pushes spool (5) until it is balanced with the
spring.
• Then, the land of the servo piston pressure pas-
sage is connected to the pump discharge pas-
sages by the cut of spool (5) and the discharge
pressure is led to the servo piston.
• The servo piston is raised by the rocker cam. The
position feedback is applied and the lever moves
to compress the spring.
• If spool (5) is pushed back, the pump discharge
circuit and the servo piston circuit are shut off.
• The pressure in the servo piston chamber lowers
and the rocker cam returns toward the maximum
swash plate angle.
• These processes are repeated until the swash
plate is fixed to a position where the EPC output
pressure is balanced with the spring force.
• Accordingly as the EPC output pressure is
heightened, the swash plate angle is decreased.
As the EPC output pressure is lowered, the
swash plate angle is increased.
PC800, 850-8
SEN00383-03
33