Kubota KX080-4 Workshop Manual page 115

KX080-4, WSM
When Pb port pressurized
(1) Independent travel valve
section
(2) LS drain plug
(3) Micro-orifice
(4) PLS pressure passage
• When the spool is shifted by the Pb port pressure, the pump pressure PPS flows to cylinder port B1 via the main
spool PC notch, compensator spool C notch, the right load check and the main spool LSC notch.
• The pressure (load pressure) in the load check upstream passage is guided to the PLS pressure passage via the
compensator spool LS pressure guide orifice (11), opening the shuttle poppet and becoming the PLS pressure;
it is then guided to the pump as the PLS signal pressure from the PLS port.
• Part of the flow of oil in the PLS pressure passage passes through the micro-orifice (3) in the LS drain plug (2)
and returns to the tank circuit.
• The pressure PPS in the pump pressure passage is guided to the pump from the independent travel valve's PPS
port as the pump signal pressure.
• Part of the oil flowing back from the actuator returns from cylinder port A to the tank circuit via the main spool CT
notch.
(5) Main spool
(6) Compensator spool
(7) Load check valve
(8) Shuttle valve
(9) Pump pressure passage
(10) Overload relief valve
(11) LS pressure guide orifice
3-M19
HYDRAULIC SYSTEM
(a) From unload valve to tank
circuit
(b) To pump
RY9212158HYM0018US0
KiSC issued 08, 2015 A