Abstract: A mechanically operated, one-turn actuation, duration spray pump mechanism for dispensing product from a container, wherein a cylinder is fixed to a cylinder retainer closure adapted to be attached to a container. In use, the cylinder extends into the container, and a splined shaft extends coaxially into the cylinder from a rotatable actuating collar connected to the cylinder retainer closure. At least one piston is mounted for axial movement on the shaft in sealed sliding relationship with the shaft and the cylinder. Interengaged structure between the piston and cylinder causes the piston to move axially within the cylinder to draw product into the cylinder and to store energy in an energy storage device when the actuating collar and shaft are rotated. The stored energy moves the piston to exert pressure on the product in the cylinder and dispense it when a discharge valve is opened.