A fuel pump assembly includes a fuel pump. The fuel pump includes a camshaft having a cam lobe. The camshaft is configured to rotate. The fuel pump includes a first cam roller and a second cam roller disposed about an outer surface of the cam lobe, a first pumping assembly configured to interact with the first cam roller, and a second pumping assembly configured to interact with the second cam roller. The second pumping assembly is offset from the first pumping assembly. The fuel pump further includes a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly.

A roller tappet device for a pump having a drive mechanism is provided. The roller tappet device includes a tappet having a longitudinal axis and a tappet housing having an internal surface area and a housing bearing. The tappet device includes a bearing shell, a bearing-shell clearance, and a pin on a side of the bearing shell that faces away from the bearing-shell clearance. The pin is received in the housing bearing of the tappet housing. The roller tappet includes a roller that has a rotation axis and is rotatably mounted within the bearing-shell clearance. The bearing shell is fixedly coupled to the tappet housing. The roller is supported on the drive mechanism; and during operation of the pump, the roller transmits a force along the longitudinal axis from the drive mechanism by way of the bearing shell to the tappet.

In a tappet-driven single piston pump, piston side loads caused by return spring out-of-squareness are eliminated by effectively piloting the piston return spring, preferably the associated spring seat, by the tappet, thereby allowing the tappet to bear the spring side load. The piston engages and is returned by the spring seat, but radial clearance between the piston and spring seat is greater than radial clearance between the spring seat and tappet, thus eliminating side loading imparted to the piston. The spring seat can be considered a piston retainer, in which the piston is not closely attached to the retainer but instead exhibits a predefined radial clearance greater than the piloting clearance between the retainer and the tappet.

A fuel pump assembly for an internal combustion engine includes a fuel pump housing, a cylindrical bore defined in the fuel pump housing, and a tappet assembly received in the cylindrical bore. The tappet assembly includes a one-piece shoe having a recess disposed in a bottom portion thereof, and a roller that is partially received within the recess and configured to rotate about a roller axis.

A fuel pump assembly includes a fuel pump. The fuel pump includes a camshaft having a cam lobe. The camshaft is configured to rotate. The fuel pump includes a first cam roller and a second cam roller disposed about an outer surface of the cam lobe, a first pumping assembly configured to interact with the first cam roller, and a second pumping assembly configured to interact with the second cam roller. The second pumping assembly is offset from the first pumping assembly. The fuel pump further includes a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly.

A fuel pump assembly includes a fuel pump. The fuel pump includes a camshaft having a cam lobe. The camshaft is configured to rotate. The fuel pump includes a first cam roller and a second cam roller disposed about an outer surface of the cam lobe, a first pumping assembly configured to interact with the first cam roller, and a second pumping assembly configured to interact with the second cam roller. The second pumping assembly is offset from the first pumping assembly. The fuel pump further includes a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly.