Abstract: An injection pump for diesel-cycle internal combustion engines includes a casing (1), a cylinder (6) within the casing and communicates, via at least one radial aperture (51), with a fuel intake chamber (3), and a piston (7) sealedly slidable within the cylinder and which, by external command, can also rotate about its axis to assume different angular orientations about a reference plane. In its jacket, a helical groove (72) opens into an axial groove (71), wherein the top, or roof, of the piston (7) is connected via a hole (77) to two channels (178, 179) provided at different levels in the piston jacket.

Abstract: Problematic noise levels in a hydraulic gear pump are overcome by exerting a radial force on the two shafts with which the gears are associated. The force has a direction and a strength that will combine with the resultant of the pressure forces and gear tooth contact forces, thereby eliminating backlash between the teeth. The system can be mechanical or hydraulic, and is incorporated either into the pump body or into pressure-balanced bearing blocks.