Abstract: An engergizing circuit for a solenoid valve has a power source connected to a solenoid coil of the solenoid valve through on-off contacts. The energizing circuit includes a capacitor and a solid-state surge absorber which are respectively connected in parallel with the solenoid coil, and the surge absorber is made from a sintered material containing a metal oxide as a principal component and having a non-linear electric resistance characteristic with respect to the applied voltage. By virtue of the solenoid valve energizing circuit constructed as described, when the on-off contacts are separated, the occurrence of an arc between the contacts thus preventing wear of the contacts, while when the solenoid coil is deenergized, the delay time in the return movement of the valve spool is decreased, and moreover the surge voltage produced across the ends of the solenoid coil upon its deenergization is controlled to a predetermined low voltage.

Abstract: A proportional electromagnetic-type direction-and throttle-controlling valve comprising a spring centered valve spool in a valve body, a pressure reducing valve, two flow restricting orifices, two DC solenoid controlled poppet valves and a vent port in each pressure chamber. Supply flow reduced to a fixed low pressure is divided into two branch lines with flow restricting orifices. The pilot pressure in each restricted flow passage with vent port is controlled by a DC solenoid-controlled poppet valve. The pilot pressure acting on the main spool end moves the spool against the spool centering spring force proportionally to the input DC current. Therefore, the flow rate through the throttling gap between the spool land and the mating valve body is controlled proportionally to input DC current. Vent ports are provided for rapid action of the spool.