Logic valves

Logic valves within the control circuit

The signal processing in the pneumatics takes place within the control circuit via logic valves. In this case, any complex logic function can be installed using the three basic logic functions "- OR - AND - NOT".

Pneumatic Logic Valves

Pneumatic Logic Valves


Logic AND-valve or two pressure valve

pneumatics two pressure valve

pneumatics two pressure valve

At the output A of logic circuit, the operating pressure will only be connected through the operating pressure when both inputs are supplied with pressure.

With different input pressure, the side with the higher pressure closes the valve and the side with the lower pressure is directed to the output.

 

Pneumatics- Two Pressure Valve or logic AND valve - function and symbol

Pneumatics- Two Pressure Valve or logic AND valve - function and symbol

Note: It is a common misconception that the shift piston must be in the center position for the two-pressure valve to connect through. This is exactly what would be an undefined switching position!

Example of use: Two-hand control with either a `two pressure valve` or as a series with two way valves.

Pneumatics logic AND circuit

Pneumatics logic AND circuit


Logic OR-valve or Shuttle valve

At the output 2 of this valve, the operating pressure is only switched through when one of the inputs 1  or 2 are applied to the operating pressure.

Pneumatics - Shuttle valve - function and symbol

The logic OR-valve appliess to a double check valve, which forwards the higher pressure at the entrance to the exit. If both inputs are pressurized, so the signal which arrives first is switched through to the outlet.


Logic NOT with pneumatic elements

In this example, the funcion `NOT`is realized by means  of a pneumatic NO1 pushbuttom. The logic here is: if the button is not pressed, but way valve is actuated and the cylinder extended.

Pneumatics Logic Not

Pneumatics Logic Not