Shibaura ST330, Workshop Manual

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2) Operation (Oil flow)
(1) Neutral position.
In the neutral position the control valve spool (4) is centered in the valve body.
Oil from the hydraulic pump is directed flows to the valve body.
The oil pressure moves the shut-off valve (5) and compressing the spring and opens the passage to the sump.
Oil flows from the pump through the passage (10) and returns to sump.
Oil trapped in the lift cylinder, under pressure caused by the weight of the implement on the lift arms, exerts pressure on
the cylinder side of the check valve (7) holding it in a closed position.
The lowering valve spool (6), positioned by the spring, retains the oil in the lift cylinder and maintains the implement in
a fixed position.
489Y
Oil flow
－
Neutral position.
1. Oil filter
2. Oil pump
3. Diverter valve Ass’y
(Relief valve Ass'y)
4. Valve spool
5. Shut-off valve
6. Lowering valve
7. Check valve
8. Lift cylinder
9. Implement
10. Oil passage