Vacuum flow sensor

A vacuum flow sensor is described according to the preferred teachings of the present invention for providing an electrical signal to the controls of a printing press or the like indicating that a sheet of paper has been picked up by the finger members and is blocking the flow of air through the finger members to the vacuum source through the vacuum passageway. Specifically, the sensor includes an actuator movable within an actuator passageway towards a first, seated position under the force of gravity and away from the first position under the force of air flowing through the vaccum passageway and against the force of gravity. A proximity switch is provided for sensing when the actuator is in its first position. The actuator passageway is angular in shape and includes a shock absorber in the end of the actuator passageway opposite to the first position for tending to prevent the actuator from bouncing in the actuator passageway due to abrupt changes in air flow through the vacuum passageway. In its preferred form, the actuator is generally cylindrical in shape and includes a reduced diameter portion defining a passage for air flow when the actuator is located in its first, seated position to provide an operating threshold for the vacuum flow sensor.