| 摘要 |
<p>A spool valve includes a body having a bore. A spool is positioned in the bore for reciprocating movement. The valve body has an inlet, an outlet and an exhaust port. An electrohydraulic three-way normally closed pulse width modulated valve has an inlet communicating with the inlet to the valve body and an outlet communicating with one end of the spool. An electrohydraulic threeway normally closed ON/OFF valve has an inlet communicating with the outlet of the body and an outlet communicating with the other end of the spool. A spring yielding urges the spool toward the valve. The spool is positioned so that it normally obstructs a path from the inlet to the outlet.</p> |
