Control of the pistons in injection pumps of internal-combustion engines

A fuel distributor injection pump comprising a pumping and distribution piston arranged coaxially with a drive input shaft of the pump and also coaxially with the axis of rotation of face-cam complementary members with which the pump is provided, said piston having a reciprocal axis pumping motion and a rotary motion for distribution of the fuel to the different cylinders of an engine, said drive input shaft being connected to said complementary face-cam members for the purpose of imparting a reciprocal rotating movement to them, said face-cam members controlling said piston to move axially, said fuel distributor injection pump being characterized by the fact that one of the said complementary face-cam members is kinematically connected to said piston by at least one cluster of gears to cause it to rotate with angular velocity less than the reciprocal velocity between the cam members, and the angular translation velocity of the axis of said at least one cluster of gears being not greater than the angular rotation velocity of said pumping and distributing piston.