Abstract: Briefly, the present invention comprises a combined mechanical shifting mechanism and pneumatic pilot valve construction to contrl the cycling of a double diaphragm pump. The mechanical cycling or shifting mechanism is positioned between pressure chambers of the diaphragm pump in the pump housing and extends axially into one or the other pressure chamber. The shifting mechanism moves axially in response to engagement by one of the pump diaphragms. Upon engagement by a diaphragm, the mechanical shift opens fluid pressure passageways to a pneumatic pilot valve which controls fluid flow to the respective pressure chambers associated with the diaphragm pump. A positive pilot signal is thus supplied through the entire stroke or cycle of the diaphragm pump. The mechanical shifting mechanism is not connected directly to a diaphragm or to the connecting rod which connects the diaphragms.