<p>Two pistons are mounted on a drive shaft with connecting rods being axially offset and adjacent one another. Each piston has an eccentric element provided in the center of the bearing and press fitted into the connecting rod via axial through bore so as not to occupy space between pistons. DEPENDENT CLAIMS are also included for the following: (A) Pump; and (B) Valve stop for retaining and supporting a flapper valve.</p>
