Shibaura ST330, Workshop Manual

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(2) Raising position.
When the position control lever is moved to the raise position, the control valve spool (4) is moved inward. The oil
passages of the control valve spool are opened and oil flows through passage (10), to the check valve (7).
The oil pressure against the check valve overcomes the check valve spring and lift cylinder oil static pressure on the
check valve, raising the check valve off its seat and allowing oil to flow to the lift cylinder to raise the implement.
When the oil pressure in the system exceeds 14.7 MPa (150 kgf/c
㎡ ) (2133 psi.), the relief valve (3) opens and oil is
returned to sump.
490Y
Oil flow － Raising position.
1. Oil filter
2. Oil pump
3. 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