748,433. Switching systems. SCHULTZ DIE CASTING CO. July 8, 1948 [Dec. 10, 1947], No. 25822/52. Divided out of 748,431, [Group XXII]. Class 38 (4). [Also in Group XXII] An electric actuating and controlling system comprises power input leads, an electric motor, a plurality of separate solenoids, circuits from the power leads to the motor and solenoids through common switching means, each solenoid having a separate controlling coil independent of the motor circuit which coil actuates a switch in the solenoid circuit. The system is described as applied to a die-casting machine (see Group XXII), the motor 19 driving a pump which produces hydraulic pressure and the solenoids 9, 10 and 11, Fig. 2, actuating valves in a pneumatic or hydraulic circuit. Power lines from a three-phase 440-volt A.C. supply are connected through a switch 23 to the motor 19 and also to the solenoids 9, 10 and 11 through relays 6, 7 and 8 respectively which are connected in a 24-volt control circuit. The circuit for the solenoid 9 is from the input line 20, to switch 23, lead 25, relay 6, line 27, coil 9, lead 28, relay 6, lead 30, to switch 23 and power line 22. Lines 20, 21 are also connected to a transformer 158 and through a switch 157 actuated therefrom to a transformer 165 supplying power to the plate circuits of thyratron valves 1-4 and to a transformer 168 which provides a 24-volt output for the relays 6, 7 and 8. Another transformer 184 supplies current to the filaments of the valves 1-4 and of a rectifier 185 which supplies the grid bias voltages for the valves. The actuation of a push button switch 169 closes the contacts of a locking relay 172 which operates through relays 175 and 181 to supply current to the transformer 168 to energize coil 6 to effect the closing of the dies of the machine through the valve-operating solenoid 9. As the dies move together, a switch is closed mechanically and so energizes a relay 295 which in turn closes a switch point 306 to energize relay 258 thus opening switch point 259 in the bias circuit of the valve 1 which at the end of the set time-delay fires through its plate circuit thereby energizing relay 220 and thence relay 7 controlling the solenoid 11. This allows lowpressure injection of metal into the dies. The energizing of relay 220 also opens the bias circuit of valve 2 which then fires and so energizes relay 227 and thence relay 8 which causes solenoid 10 to actuate a valve causing injection of metal at a higher pressure. The energizing of relay 227 also removes the bias from valve 3 which fires to energize relay 232 to rebias valves 1 and 2, the rebiasing of valve 3 itself being prevented by the opening of switch point 266. After a time-delay sufficient for the injected metal to cool in the dies, which period is determined by the potentiometer 292, valve 4 fires thereby energizing coil 239 and thereby breaking the holding circuit of the relay 172 thus allowing the reopening of the dies by spring means. The de-energizing of relay 172 also de-energizes relays 295 and 258, closing switch points 259, 260 and 261 to rebias valves 3 and 4. In a modification the machine is controlled by a circuit employing rive electronic valves and having no common switching means for the motor and solenoid circuits. In this modification the fifth valve is used instead of a relay connection for closing the dies. Specification 748,449 is referred to.