Abstract: The pump has a body including at least a fuel compression chamber and an actuating chamber enclosing the actuating members of the pump; the on-off valve is defined by an independent operating assembly insertable in fluidtight manner inside a hole in the body; the hole connects an inlet conduit to the actuating chamber and to a feed conduit of the compression chamber; the assembly of the valve has a sleeve in turn having an opening located at the fuel feed conduit and which is closed by a shutter sliding inside the sleeve; the sleeve has two seats for two seals located on opposite sides of the opening; and the feed conduit is straight, and can be formed using a drilling tool through the hole.

Abstract: A constant-pressure delivery valve for fuel injection pumps for diesel engines includes a conical-surface obturator to which is fixed a body forming an axial chamber containing a calibrated one-way valve with a ball obturator. The ball obturator is located on that side of the chamber facing the conical-surface obturator and controls communication between radial and axial fuel return passages formed beneath the bottom of the chamber.