Subclass : POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (engine fuel-injection pumps F02M ; machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C ; non-positive-displacement pumps F04D ; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F ; crankshafts, crossheads, connecting-rods F16C ; flywheels F16F ; gearings for interconverting rotary motion and reciprocating motion in general F16H ; pistons, piston-rods, cylinders, in general F16J ; ion pumps H01J 41/12 ; electrodynamic pumps H02K 44/02 )