Kubota B2910, Workshop Manual

Page: 402 / 426

1-M1
B7800HSD (SUPPLEMENT), WSM HYDRAULIC SYSTEM
1. CONTROL VALVE (QUARTER INCHING VALVE)
This implement control valve (quarter inching valve) is located under the hydraulic cylinder block.
Q
Neutral
Oil forced into the control valve (1) through P port and
returns to the transmission case through T1 port.
Also, C port is closed by spool (2), oil in the hydraulic
cylinder does not flow to the transmission case.
Thus, the implement remains at its fixed position.
W1012665
Q
Up
When the control lever is set to the “ Up ” position, the
spool (2) is moved to the left.
The oil forced into the control valve (1) through P port
flows to C port.
The oil pushes and flows into the hydraulic cylinder
through the C port to lift the implement.
W1012786
Q
Slow Up (Quarter Inching Control)
When the hydraulic control lever (3) is set to “ SLOW
UP ” position ( C ), the spool (2) is slightly moved to the left.
The oil forced into the control valve (1) from P port
flows to C port in response to the movement of the
hydraulic control lever (3).
Since the spool (2) is two stepped land spool, the oil
forced in the oil passage ( IP ) between the spool (2) and
the control valve body is throttled, and less quantity of
hydraulic oil flows from
P port, through this oil passage
( IP ), to C port.
At this time, the hydraulic control lever (3) enables to
control the valve easily in increments of approximately 1/
4 inches “
SLOW UP ” at the lower link end.
W1019771
(1) Control Valve
(2) Spool P: Pump Port
C: Cylinder Port
T
1
: Tank Port 1
T
2
: Tank Port 2
(1) Control Valve
(2) Spool P: Pump Port
C: Cylinder Port
T
1
: Tank Port 1
T
2
: Tank Port 2
(1) Control Valve
(2) Spool
(3) Hydraulic Control Lever
P: Pump Port
C: Cylinder Port
T
1
: Tank Port 1
T
2
: Tank Port 2
A: Down
B: SLOW DOWN
C: SLOW UP
D: UP
N: NEUTRAL
IP: Oil Passage (Pump Side)
KiSC issued 09, 2007 A