Kubota KX080-4 Workshop Manual page 113

KX080-4, WSM
During operation of LS section
(1) Independent travel valve
section
(2) LS drain plug
• When the spool section is switched, the oil in the pump pressure passage passes through the main spool and is
discharged to the cylinder port. The operating load pressure of the cylinder port is guided from inside the spool
section to the PLS pressure passage (4) and becomes the PLS pressure. (Refer to the explanation of how the
spool section operates.)
• When the amount switched from the spool section is great, the area of the spool section that opens is large, so it
reduces the pressure differential (PPS-PLS) between the pump pressure PPS and PLS.
• When the pressure differential (PPS-PLS) between the pump pressure PPS and PLS drops to the unload valve
setting pressure, the unload spool moves to the left side, closing the opening at the notch between the pump
pressure passage and the tank circuit, thus completely closing the unload spool.
• If the pressure differential (PPS-PLS) between the pump pressure PPS and PLS drops further to the LS limit
pressure differential setting set for the pump, it increases the pump's swash-plate tilt angle, thus increasing the
pump's discharge flow rate.
• The pump automatically changes the discharge flow rate according to the amount the spool section is switched
and changes in the operating load pressure, thus limiting it to maintain a constant differential pressure (PPS-PLS)
between the pump pressure PPS and PLS.
(3) Micro-orifice
(4) PLS pressure passage
(5) Notch
3-M17
HYDRAULIC SYSTEM
(a) To each spool section
RY9212158HYM0016US0
KiSC issued 08, 2015 A