A hollow shaft includes a cylindrical main body part and an extremity drawn part that is integrally connected to one end of the main body part on the same axis and whose diameter is made smaller than a diameter of the main body part by drawing processing, wherein an inner peripheral face of the main body part and an inner peripheral face of a base portion, which is continuous with one end side of the main body part, of the extremity drawn part are formed as cut faces that are subjected to cutting processing before the drawing processing, and an inner peripheral face of a tip portion, which is continuous with an extremity side of the base portion, of the extremity drawn part is a non-cut face. Accordingly, the hollow shaft can be molded with high shape precision while maintaining a low drawing ratio for an extremity drawn part.

A hollow shaft includes a cylindrical main body part and an extremity drawn part that is integrally connected to one end of the main body part on the same axis and whose diameter is made smaller than a diameter of the main body part by drawing processing, wherein an inner peripheral face of the main body part and an inner peripheral face of a base portion, which is continuous with one end side of the main body part, of the extremity drawn part are formed as cut faces that are subjected to cutting processing before the drawing processing, and an inner peripheral face of a tip portion, which is continuous with an extremity side of the base portion, of the extremity drawn part is a non-cut face. Accordingly, the hollow shaft can be molded with high shape precision while maintaining a low drawing ratio for an extremity drawn part.

A cladding structure and method for cladding machine components to inhibit crack propagation includes at least one set of primary bands, with each primary band being deposited adjacent to and abutting at least one other primary band, forming at least one inter-pass clad boundary, and at least one set of secondary bands deposited in a spaced configuration and oriented so as to intersect at least one inter-pass clad boundary.

A bearing assembly for a downhole motor is provided. The bearing assembly includes a housing and a drive shaft designed to rotate with respect to the housing. The bearing assembly also includes stackable thrust bearings, each pre-loaded via a corresponding spring component. Some thrust bearings are arranged such that their spring components distribute axial loads from the housing in a first direction to the thrust bearings. Other thrust bearings are arranged such that their spring components distribute axial loads from the drive shaft in the first direction to the thrust bearings. Thus, the bearing assembly may be tailored via the stackable bearings to distribute axial thrust forces on the downhole motor evenly across the different thrust bearings. The bearing section may include a machinable spacer used to provide a double shouldered connection between the drive shaft and a drive shaft cap used to compress the stackable bearings.

In a mud-lubricated bearing assembly for a downhole motor, a mechanical seal is provided between the mandrel and the lower end of the bearing housing to prevent discharge of drilling fluid (mud) from the bearing assembly into the wellbore annulus. The mechanical seal is effected by mating wear-resistant annular contact surfaces provided on the mandrel and the bearing housing, with biasing means preferably being provided to keep the contact surfaces in sealing engagement during both on-bottom and off-bottom operational modes. The diverted drilling fluid passing through the bearings is redirected into the bore of the mandrel via ports through the mandrel wall to rejoin the main flow to the drill bit, such that substantially all of the drilling fluid flows through the bit.

A method is disclosed of manufacture of a component (9) with an internal groove (2,3) comprising: providing a tubular first part (1) with an external groove, bonding or forming a second part (8) on the first part to at least partly cover the external groove, and removing material from the first part to open the external groove to an interior cavity of the component.

A method is disclosed of manufacture of a component (9) with an internal groove (2,3) comprising: providing a tubular first part (1) with an external groove, bonding or forming a second part (8) on the first part to at least partly cover the external groove, and removing material from the first part to open the external groove to an interior cavity of the component.

A shaft can include a first portion comprising a first material having first material properties, a disconnect portion comprising at least some of a second material having second material properties, and a third portion comprising a third material having third material properties. The disconnect portion can be positioned between the first portion and the third portion, the three material properties being configured such that the first portion is physically disconnected from the third portion in response to failure of the disconnect portion under at least one of a mechanical load and/or an electrical load and/or thermal load.

A shaft can include a first portion comprising a first material having first material properties, a disconnect portion comprising at least some of a second material having second material properties, and a third portion comprising a third material having third material properties. The disconnect portion can be positioned between the first portion and the third portion, the three material properties being configured such that the first portion is physically disconnected from the third portion in response to failure of the disconnect portion under at least one of a mechanical load and/or an electrical load and/or thermal load.

A microfabricated fluidic unidirectional valve includes a microfabricated elastomer material having a flow through channel. The microfabricated fluidic unidirectional valve also includes an elastomer flap attached to the elastomer material in the flow through channel. The elastomer flap forms a seal in the flow through channel to prevent fluid from flowing in a first direction through the flow through channel and to allow fluid flow in a second direction through the flow through channel.