| 摘要 |
<p>A control valve comprises a first spool 22, a second spool 24 encircling at least part of the first spool 22 and angularly moveable relative thereto, and a sleeve 32 encircling at least part of the second spool 24, the second spool 24 being angularly moveable relative to the sleeve 32, the first and second spools 22, 24 having first and second series of ports 28, 30 registrable with one another, depending upon the relative angular positions of the first and second spools 22, 24, to control communication between at least a pressure line 16, a return line 18 and a control line 50 provided in or connected to the sleeve 32, the second spool 24 and the sleeve 32 having third and fourth series of ports 66, 68, axially spaced from the first and second series of ports 28, 30 and registrable with one another, depending upon the relative angular positions of the second spool 24 and the sleeve 32, to control communication between at least the control line 50 and the return line 18, and latch means 56 operable to resist movement of the second spool 24 relative to the sleeve 32.</p> |
