Kubota WSM STa-30, Workshop Manual

Page: 287 / 359

9-M9
ST
α
-30, ST
α
-35, WSM HYDRAULIC SYSTEM
6. FLOW PRIORITY VALVE
[1] FUNCTION AND STRUCTURE
The flow priority valve is a flow divider that divides the
flow from single hydraulic source (hydraulic pump) and
actuates two circuits (position control circuit and Bi-
speed turn circuit) simultaneously. This valve feeds
fixedly controlled flow to the PF side (Bi-speed turn
circuit) with priority and remainder to the EF side
(position control circuit).
W1014939
[2] OIL FLOW
■
Unloading Condition
1. When the engine starts, oil flows into the valve
through P port (9).
2. A pressure difference is created between the ends of
the orifice (1) as the flow passes the orifice (1). This
causes the plunger (6) to move to the right, deflecting
the spring (4).
3. Then the oil passage is formed in portion B shown left
figure, and the remainder flows to the EF port
(position control circuit).
(Reference)
• The damper orifice prevents plunger vibration caused
by a sudden change in engine rpm (change in the oil
flow rate).
W1015071
(1) Orifice
(2) PF Port
(3) Portion A
(4) Plunger Spring
(5) Damper Orifice (6) Plunger
(7) EF Port
(8) Portion B
(9) P Port
(1) Orifice
(2) PF Port
(3) Portion A
(4) Plunger Spring
(5) Damper Orifice (6) Plunger
(7) EF Port
(8) Portion B
(9) P Port
KiSC issued 11, 2006 A