An electric motor, in particular for an oil pump, comprising a rotor and a stator, wherein the stator has through-openings, which are continuous in the axial direction, for screw elements, and comprising a functional support, which is arranged on an end face with respect to the axial direction of the stator and which has a contoured contact section for the stator and screw receiving areas for the screw elements. The screw receiving areas protrude out of the contoured contact section for the stator in the axial direction, and the screw receiving areas are received in the through-openings.

A screw having a cylindrical shank with a conical tip at one end and a screw head at the other, and at least one thread section therebetween. The thread section has a thread core. On the thread section, multiple successive thread terms are formed on a shell surface of the thread core. In the region of the thread section, multiple elevations are arranged on the outside of the shell surface of the thread core.

A crack-proof screw includes a thread formed around a shank. A helical notch continuously and helically extends along the shank and is indented into the shank and the thread. The helical notch is proximal to but spaced apart from a tip of the shank. The notch is trapezoidal in cross section, and has a notch bottom, an open end opening at an outer peripheral surface of the shank oppositely of the notch bottom, and two opposite notch walls extending divergingly from the notch bottom to the open end. The open end is larger in width than the notch bottom. A method of making the screw is also disclosed.

Provided is a feed mechanism that has a small number of parts and that is suitable for downsizing. A feed mechanism (1) includes: a base (2); a movable body (3); a feed screw (4) configured to move the movable body (3) relative to the base (2); and a torque generation member (15) formed with a female thread (15b) that is threadedly engaged with the feed screw (4). The movable body (3) is formed with a housing hole (12) extending in a direction orthogonal to the feed screw (4), and the torque generation member (15) is housed in the housing hole (12).

There is provided a seizure prevention bolt capable of preventing seizure caused by oblique insertion as well as seizure caused by invasion of a foreign matter such as a spatter. An incomplete screw portion having an outer diameter d that is larger than an inner diameter D.sub.1 of a female screw and smaller than (D+D.sub.1)/2 is formed at a front end of a normal screw portion formed in a bolt shaft over one or more pitches, and a vertical groove for cutting out a foreign matter such as a spatter is formed in the incomplete screw portion. D in the above expression is a nominal diameter of the bolt.

A fastening structure for fastening a to-be-fastened component to a wooden component by using a screw, wherein the wooden component is made of wood having a specific gravity of 0.08 g/cm.sup.3 to 0.85 g/cm.sup.3 inclusive, the screw has a nominal diameter of 0.8 mm to 3.5 mm inclusive, and the distance between a neutral position in a longitudinal direction of an effective screw part, which is the portion where the wooden component and a male screw part formed in a shaft part of the screw mesh together, and the surface of the wooden component that comes into contact with the to-be-fastened component is 1 mm to 15 mm inclusive.

A screw with an improved screw head is provided. The screw may include a shank having a threaded portion and a head. The head may have a side and a plurality of protrusions positioned along the side. Each protrusion may comprise an outer wall, and a trailing wall and a leading wall each extending between the outer wall and the side of the head. The leading wall may define a plurality of leading surfaces. The plurality of leading surfaces may comprise a first leading surface extending inwardly from the outer wall, a second leading surface extending inwardly from the first leading surface, and a third leading surface extending between the second leading surface and the side of the head. The plurality of leading surfaces may provide curvature to the leading wall and a substantially smooth transition between the outer wall and the side of the head.

A screw with an improved screw head is provided. The screw may include a shank in between a head and a tip. The head may include a plurality of protrusions provided radially along the head. Each of the plurality of protrusions may include a protrusion wall, a leading wall, a trailing wall, and a bottom wall; the trailing wall may include one single trailing surface, the leading wall may include a plurality of leading surfaces, and the bottom wall may include at least one bottom surface.

A surgical screw is provided for use in fixing or fusing bone. The screw may include each of an inner and an outer helical thread that extends along its length. The geometries of the helices and the relationship between the inner thread and the outer thread may improve the performance of the screw. For example, the two helices may operate to improve the manner in which the screw can be strained.