Komatsu PC600LC-7 Manual page 74

STRUCTURE, FUNCTION AND MAINTENANCE STANDARD
1) Operation in direction of increase of pump discharge amount (max. angle)
Operation
• The control pump pressure PPO is taken to port
a.
• Signal pressure PECN from the NC valve is tak-
en from port b to chamber c.
• When signal pressure PECN rises, piston (8) is
pushed to the right by the pressure in chamber c,
and stops at a point where it balances the pres-
sure of springs (4) and (4A).
• At the same time, arm (6) uses servo piston (19)
as a fulcrum and sways to the right in the same
way as piston (8). This moves guide spool (13) to
the right.
• When guide spool (13) moves, port a and port d
are closed and port d is connected to drain
chamber e. As a result, servo piston chamber f is
also interconnected with drain chamber e
through port g and port d.
10-42
HYDRAULIC PUMP (PISTON PUMP)
• At the same time, port a is interconnected with
port h, so the pressure oil flows through port i to
servo piston chamber j, pushes servo piston (19)
to the right, increases the swash plate angle in
the main piston pump and increases the pump
discharge amount.
• When servo piston (19) moves, arm (6) rotates
counterclockwise with its center at pin (7) and
moves guide spool (13) to the left. Port a, port d
and port h close, so the discharge increases by
an amount that matches signal pressure PECN.
PC600, 600LC-7