Komatsu PC600LC-7 Manual page 77

STRUCTURE, FUNCTION AND MAINTENANCE STANDARD
Function
• When the power mode is A-mode or E-mode, the
pump discharge amount is set properly with the
command current sent from the controller ac-
cording to the engine speed.
1) When command current value from controller is small in A and E mode
Operation
• The command current sent from the controller
actuates solenoid push pin (9) and spool (2)
moves. When this happens, spool (2) stops at a
point where it balances the total of the force of
spring (1), the force of push pin (9), and the force
of TVC output pressure PE acting on piston (3).
At this time, since the command current and the
force of push pin (9) are small, spool (2) is bal-
anced on the lower side.
PC600, 600LC-7
HYDRAULIC PUMP (PISTON PUMP)
• When the emergency pump drive switch is
turned ON, the pump discharge amount is con-
trolled according to the pump discharge pressure
(load) by sensing the oil pressure at constant
pump absorption torque.
• As a result, ports "a" and "b" are opened almost
fully and almost all the oil from the control pump
is output as TVC valve output pressure PE.
Then, TVC valve output pressure PE and signal
pressure PECN increase, thus the pump dis-
charge amount increases.
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