1. Air supply interruption self-locking. Air supply interruption self-locking device consists of a control valve and two air valve. Under normal circumstances, control valve diaphragm to close the valve mouth of A, B valve mouth open. This work room air through control valve film and make the two open air valve open, two piston action by the locator amplifier output pressure control. When the origin of pressure drop to closure pressure (adjustable), due to the lower part of control valve diaphragm pressure decreases, and diaphragm moves down, to close the valve opening of valve port open and B, control valve mold chamber and atmosphere are interlinked, gas origin was cut open valve control and close, cause the amplifier to the piston, the cylinder of the gas circuit is cut off, the piston to stay in the original position. Closure pressure values available manual adjustment knob, usually don't allow less than 300 kpa. 

2. Air supply is interrupted and self-locking. On the basis of air supply interruption and self-locking, increase a two-position  three-way solenoid valve,  the power supply and self-locking can be realized. When the power supply is normal, the solenoid valves 1-2 is electrified. When power is interrupted, the solenoid valve acts, making the solenoid valves 2-3 electrified, because the  port of solenoid valve 3 is to  the atmosphere, making the air source lose pressure, which is equal to that the air supply is interrupted and self-locking. 

3. The electrical signal is interrupted and self-locking. Connect resistance R1 in series in the power signal circuit, the voltage drop of signal current on R1 is served as the input voltage of switch signal. Under normal circumstances, the voltage on Rl is larger, the contact of the relay is closed via the switching circuit. When the electric signal is interrupted, the voltage of R1 drops to zero, the switch circuit makes the relay J to act to disconnect the contact , so the solenoid valve power is off, which is equal to the power supply interruption and self-locking at this moment.