| 摘要 |
An electrohydraulic control system comprising a spool valve including a body having a bore. A spool is positioned in the bore for reciprocating movement within the bore. 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 three-way 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 yieldingly urges the spool toward the pulse width modulated valve. The spool is positioned so that it normally obstructs a path from the inlet to the outlet. |
