A Pneumatic Toggle clamps is a basically a Toggle Clamp actuated with a double acting pneumatic cylinder.
Air pressure in applied in the clamping port, which thereby moves the clamping arm to hold the work piece. A required clamping force is achieved and exerted on the work piece. Under this action the Toggle Clamp Holds the work piece firmly and positively. To unlock the clamp the air pressure is applied in the unclamping port.