Abstract: A pneumatic control valve system has a modulating valve and a piston. When the operator depresses the piston, pressure is communicated to a switching piston moving that piston to a switched position so that pressure is communicated to a switching outlet. The switching piston retains this switched position when the first piston is released. When the modulating valve is opened to communicate pressure to a work port, pressure is also communicated to the switching piston in order to move the switching piston back to its unswitched position whereat the switching outlet is vented. The switching piston allows the control of another function.

Abstract: A modulator valve has a modulator member which is slidably mounted in a cylinder and through which an air flow passage extends. A valve member is slidably mounted in the air flow passage and is operable to open and close the through passage. By providing a resilient actuator for displacing the modulator member in a first direction and a stop for arresting the movement of the flow control valve while permitting movement of the modulator valve it is possible to provide for modulated opening and closing of the control valve by balancing the pressure applied by the resilient actuator against the air pressure applied to the modulator member downstream of the through passage.