Systems and methods are described for a reciprocating mechanism. The system includes at least one axially translating y-axis component configured to reciprocate substantially along a y-axis with a reciprocating motion of a piston assembly relative to a base. The system also includes at least one x-axis component slidingly coupled via at least one bearing assembly to and translating with the at least one y-axis component along the y-axis. The at least one x-axis component is configured to reciprocate substantially perpendicularly to the y-axis relative to the at least one y-axis component, and includes an orbital output component and an orbital linking component disposed substantially concentric with the orbital output component. The system also includes a stationary output component rotatably attached to the base in a direction that is substantially perpendicular to both the x-axis and y-axis, and a stationary linking component rotatably attached to the base in a direction that is substantially concentric with the stationary output component.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

An electro-hydraulic control unit for a vehicle brake system includes a hydraulic control unit including an HCU block defining a motor bore containing an electric motor and an eccentric chamber containing a rotating eccentric driven by the electric motor. The HCU block also defines a pump bore containing a piston pump including a piston rod having a generally cylindrical shape with a smooth exterior surface extending substantially its entire length. An end cap is press fit around an end of the piston rod and includes a flange portion extending annularly outwardly for engaging a return spring. A piston guide includes a tubular portion guiding the piston rod and a shoulder for engaging the return spring. A throat of the piston guide holds a gland seal surrounding the piston rod. An outlet valve housing includes a tubular protrusion extending into the throat of the piston guide to hold the gland seal.

A piston includes a piston cap, a piston rod body, and a piston head, with the piston cap being removable from the piston rod body. The piston cap includes a cap body and a connecting portion extending from the cap body and away from the piston rod body. The connecting portion includes a neck and a cap head with the cap head connected to an end of the neck disposed opposite the piston rod body. The cap head is wider than the neck. A mounting portion of the piston rod body extends into a receiving portion of the cap body to connect the piston rod body to the piston cap.

A piston includes a piston cap, a piston rod body, and a piston head, with the piston cap being removable from the piston rod body. The piston cap includes a cap body and a connecting portion extending from the cap body and away from the piston rod body. The connecting portion includes a neck and a cap head with the cap head connected to an end of the neck disposed opposite the piston rod body. The cap head is wider than the neck. A mounting portion of the piston rod body extends into a receiving portion of the cap body to connect the piston rod body to the piston cap.

A piston includes a piston cap and a piston rod with the piston cap being removable from the piston rod body. The piston cap includes a cap body and a socket extending into the cap body. A mounting portion of the piston rod body extends into the socket of the cap body to connect the piston rod body to the piston cap. A wear sleeve is mounted on the piston rod.

A piston includes a piston cap and a piston rod with the piston cap being removable from the piston rod body. The piston cap includes a cap body and a socket extending into the cap body. A mounting portion of the piston rod body extends into the socket of the cap body to connect the piston rod body to the piston cap. A wear sleeve is mounted on the piston rod.

The present disclosure provides an oil scavenge pump, which includes a cap member, a piston member and a resilient member. The cap member and the piston member are connected to each other and with the resilient member therebetween. The cap member includes a cap head, a valve connected to the cap head, a resilient unit disposed between the cap head and the valve, and a first sphere disposed between the resilient unit and the valve. The piston member includes a valve stopper, a main portion, a second sphere, a rod portion, a first-seal ring and a second-seal ring. The main portion has two ends respectively connected to the valve stopper and the rod portion. The second sphere is disposed between the valve stopper and the main portion. The first-seal ring and the second-seal ring respectively surround the main portion and the rod portion.

A suction cover assembly for a frac pump includes a suction cover having an annular base flange defining a sealing interface proximate to the base flange. The suction cover is dimensioned to be accommodated within a bore well of a fluid cylinder in the pump. An annular seal is seated on the sealing interface proximate to the base flange of the suction cover.