Signal Circuit - Kubota KX080-4 Workshop Manual

KX080-4, WSM

(9) Signal Circuit

(1) Independent travel valve
section
(2) Communication valve section
(3) P3 bypass section
(4) Independent travel valve
spool
(5) Communication valve spool
(6) Filter
[In neutral]
• Pilot pump pressure is guided to the hydraulic supply ports PP1, PP2 and PP3 of the signal circuit.
• The pilot pump pressure supplied to port PP1 of the P3 bypass section returns to the tank circuit via the filter (6)
and micro-orifice (7) and via the main spool signal passage switch (19) of all sections so port PAI port=tank
pressure.
• The pilot pump pressure supplied to port PP2 of the communication valve section (2) returns to the tank circuit
via the filter (6), micro-orifice (7) and the open center passage of the communication valve spool (5), and via the
main spool signal passage switch of the travel section. And oil in the passage split at a point upstream of the travel
section's main spool signal passage switch is guided to the independent travel valve section as well, and is
connected to the PT port pressure chamber via the ring-shaped gap (8) of the independent travel valve spool (4).
• The pilot pump pressure supplied to port PP3 of the main valve returns to the tank circuit via the filter (6) and
micro-orifice (7) and via the main spool signal passage switch of each of the arm→bucket→S/P1→boom→swing
section, so port PF1 port=tank pressure.
• The PF1 port is connected via external lines with the PF2 port of the communication valve section (2), so
PF1=PF2=tank pressure.
(7) Micro-orifice
(8) Ring gap
(9) Swivel
(10) Blade
(11) AUX2
(12) Travel left
(13) Travel right
(14) Arm
(15) Bucket
(16) AUX1
(17) Boom
(18) Swing
3-M27
HYDRAULIC SYSTEM
(19) Main spool signal passage
section
(20) Area receiving pressure: A1
(21) Area receiving pressure: A2
(a) To pump
(To be continued)
KiSC issued 08, 2015 A