Method of forming a seal between a control shaft and bushing

摘要

An air driven diaphragm pump having two diaphragms joined by a common control shaft to reciprocate in opposed chambers for pumping material through check valve ported cavities. An actuator valve is associated with the central housing of the pump and includes a valve cylinder within which a valve piston reciprocates. The valve piston is caused to reciprocate by alternate venting of the ends of the cylinder. Enlarged air chamber passages are controlled by the control shaft to vent the ends of the valve cylinder. A cylindrical portion of the control shaft includes axial slots for venting alternate ends of the valve piston. Annular channels manifold air to and from the axial slots. The actuator housing is molded about the center bushing for the control shaft and includes inwardly extending portions. Annular passages are then machined in the bushing for sealing channels to receive O-rings. The O-rings extend to seal against the housing directly at the floor of the sealing channels.