Abstract: A fuel pump housing includes a pumping chamber that is substantially spherical and a drilling intersecting the pumping chamber at an opening. The drilling transitions into the pumping chamber at a transition region of progressively increasing diameter. The transition region and the spherical pumping chamber are configured such that a peak stress in the fuel pump housing is at a location that is spaced away from the opening.

Abstract: A tappet suitable for use with a fluid pump includes a side wall portion and an end face which define an internal chamber of the tappet, the end face having a drive surface for co-operating with a drive arrangement, in use, and a plurality of vents through the end face for allowing fluid flow between the internal chamber and an area outside the tappet. A plurality of longitudinal grooves are formed in an internal surface of the side wall portion, the grooves communicating with respective the vents to form a flow path for fluid into the internal chamber.

Abstract: Fuel pump for common rail engine comprises a plunger reciprocal within a bore to pressurize fuel within a chamber. A drive fir the plunger is co-operable with a cam rider so as to impart axial drive to the plunger while permitting lateral sliding movement of the cam rider. A plunger cycle includes a forward stroke, during which fuel within the chamber is pressurized, and a return stroke, during which the pump chamber fills with fuel at low pressure. The pump comprises a load-reducing arrangement for reducing the load on the drive due to fuel pressure within the chamber during that period of the forward stroke for which the relative velocity of sliding movement between the drive and the cam rider is at a minimum, thereby to reduce wear of the drive.

Abstract: A tappet suitable for use with a fluid pump, wherein the tappet comprises a side wall portion and an end face which define an internal chamber of the tappet, the end face having a drive surface for co-operating with a drive arrangement, in use, and a plurality of vents through said end face for allowing fluid flow between the internal chamber and an area outside the tappet. A plurality of longitudinal grooves are formed in an internal surface of said side wall portion, said grooves communicating with respective said vents to form a flow path for fluid into the internal chamber. The invention also relates to a pump assembly having such a tappet.

Abstract: A fuel system is described which comprises a high pressure fuel pump arranged to supply fuel under pressure to a plurality of injectors. A backleak connection line is arranged to return fuel from the injectors to a fuel reservoir. A venturi pump is connected to the backleak connection line and is arranged to draw fuel from the line to reduce the fuel pressure therein.