Abstract: The present invention is concerned with a dual stroke drive mechanism of any size for a reciprocating device, such as a piston of a pump. It is particularly concerned with such a driving mechanism having means for selecting a particular stroke-length. It is more specifically concerned with a drive mechanism capable of imparting either one of two set stroke-lengths and means for selecting one of the stroke lengths before, or at certain intervals during, operation of the mechanism. The drive mechanism converts rotary movement of an input member into reciprocating rectilinear movement of an output member which may be connected to a piston and reciprocates the latter. A preferred application is in the field of sampling pumps for distributing liquid samples of small sizes into vials for analysis.

Abstract: The invention is concerned with a novel container for receiving a liquid material having a fitting at one end adapted to provide a discharge port for the liquid within the container and having at its other end a plunger or piston adapted to be moved within the inside wall of the container to discharge one or more predetermined "aliquots" or "doses" of liquid from the container through the port. The invention also comprises a novel device adapted to receive a liquid-containing cartridge or package of the type just mentioned and having means for coacting with the package to move the plunger within the container during dose-dispensing or -discharge in such a manner as to gradually accelerate movement of the plunger from a position of rest within the container through a maximum rate of motion and then gradually decelerate the motion of the plunger to a final position at the end of the dose-discharge.