A fluid end assembly of a hydraulic fluid pump includes a housing having a bore, a removable valve cover closing the bore, and a retainer engaging the bore. The retainer includes a set screw bore that extends from a first side of the retainer to a second side of the retainer, opposite the first side. The fluid end assembly further includes a set screw. The set screw is threaded into the set screw bore from the first side of the retainer. The set screw is not removable from the second side of the retainer. The first side of the retainer is positioned adjacent to the valve cover.

A fluid end assembly of a hydraulic fluid pump includes a housing having an axial bore, a removable valve cover closing the axial bore, and a retainer engaging the axial bore. The retainer includes a central opening. The fluid end assembly further includes a threaded drive member positioned within the central opening and operable to apply a preload against the retainer.

An engine block comprising: a combustion chamber, an inlet for introducing a fuel/air mixture into the combustion chamber and an outlet for expelling combusted fuel/air mixture from the combustion chamber; and a piston that reciprocates within the combustion chamber to compress the fuel/air mixture therein, the piston having a closer supported thereon, wherein reciprocating movement of the piston seals the combustion chamber with the closer.

A pressure amplifier (1) is described comprising a housing (2) a low pressure chamber (9-12), a high pressure chamber (13-16) and for transmitting means between the low pressure chamber (9-12) and the high pressure chamber (13-16). Such a pressure amplifier should have a compact design. To this end the force transmitting means comprise a rotor (3) arranged in a bore (4) of the housing (2), wherein the rotor (3) comprises a radially extending low pressure wing (5, 6) and a radially extending high pressure wing (7, 8), the low pressure wing (5, 6) together with the housing (2) delimiting the low pressure chamber (9-12) and the high pressure wing (7, 8) together with the housing (2) delimiting the high pressure chamber (13-16), wherein a supply of fluid into the low pressure chamber (9-12) causes a rotation of the rotor (3) and a rotation of the rotor causes a decrease of volume of the high pressure chamber (13-16).

An engine block comprising: a combustion chamber, an inlet for introducing a fuel/air mixture into the combustion chamber and an outlet for expelling combusted fuel/air mixture from the combustion chamber; and a piston that reciprocates within the combustion chamber to compress the fuel/air mixture therein, the piston having a closer supported thereon, wherein reciprocating movement of the piston seals the combustion chamber with the closer.

An end cap assembly for a reciprocating air motor comprises a pilot valve and an end cap body. The pilot has a valve stem. The end cap body comprises a central bore for receiving an air motor rod, a valve bore in which the pilot valve is disposed such that the valve stem extends through the end cap body, and an air port extending through the end cap body. The air port has a contour to direct air toward the valve stem.