Abstract: A pump assembly for use in delivering fuel to a common rail of an internal combustion engine, including a pumping plunger (28; 128) which is co-operable with an intermediate drive member in the form of a tappet (34). The tappet (34) is co-operable with an engine-drive cam (11), in use, so as to impart drive to the plunger (28; 128). A cam rider member (38) of generally tubular form has an inner surface which co-operates with the cam (11) and an outer surface which cooperates with the bucket tappet (34). A main pump housing (10) is provided with a radially extending opening (18a) within which is received, at a first end thereof, a separate pump head (20a) and, at a second end thereof, the tappet (34) so that the opening (18a) serves to guide axial movement of the tappet (34), in use. The separate pump head (20a) is provided with a plunger bore (26) which serves to guide movement of the plunger (28; 128) and within which is defined a pump chamber (30) in which fuel is pressurised as the plunger (28) is driven.

Abstract: The present invention relates to a radial piston pump, and more particularly to a radial piston pump suitable for delivering liquid at a high pressure and at a volumetric output rate which can be controlled independently of the speed of rotation of the pump drive shaft. A radial piston pump(1) is provided which comprises a multiplicity of radially extending cylinders(14) each of which is provided with a radially moveable pumping plunger(15) to define, within the cylinder, a pumping chamber(16) which may be increased in volume by a movement of its associated plunger(15) in one direction to receive a liquid to be pumped and may be reduced in volume by movement of its associated plunger(15) in the opposite direction to deliver a liquid at high pressure to an output line. The pump(1) also comprises means for selectively disabling one or more of the pumping chambers(16) so that the or each disabled pumping chamber delivers no pumped fluid to the output line.