Rocking Piston Pumps combine the higher performance of a piston pump with the simplicity of a diaphragm pump in a small economic unit.  The piston is fixed rigidly to the top of the connecting rod.  An eccentric drive causes the piston to reciprocate and a flexible seal maintains contact with the cylinder walls, compensating for the rocking motion.  The pumps are capable of operating continuously with a minimum of maintenance and offer high performance, particularly pressure, within a compact package.