A gyroscopic roll stabilizer includes an enclosure, a flywheel assembly, and a motor. The enclosure is mounted to a gimbal for rotation about a gimbal axis and configured to maintain a below-ambient pressure. The flywheel assembly is rotatably mounted inside the enclosure for rotation about a flywheel axis. The flywheel assembly includes a flywheel and flywheel shaft. The flywheel shaft has a first end and an opposite second end; a first cavity formed in the first end and facing away from the second end; and a second cavity formed in the second end and facing away from the first end. The flywheel shaft has a longitudinal passage connecting the first cavity and the second cavity. This longitudinal passage may be used for inspection of one of the cavities and/or an associated seal, from the direction of the other cavity. Related methods are also disclosed.

A motor rotor includes a rotatable shaft, and a magnet structure mounted around the shaft. The magnet structure includes magnet pieces including a first magnet piece and a second magnet piece. The first magnet piece has a fracture surface facing the second magnet piece, and an outer surface forming a circumferential surface of the magnet structure. A surface roughness of the fracture surface is greater than a surface roughness of the outer surface of the first magnet piece.

Disclosed is a conduction-cooled magnetic flux pump, comprising a refrigerator, a cooling capacity conducting part, a cooling capacity conducting plate, a high-temperature superconducting coil, a high-temperature superconducting tape, an L-shaped machined part, a dynamic sealing device, a motor, a rotating shaft, a bow-shaped epoxy resin machined part, a permanent magnet rotor disk, and a permanent magnet. The cooling capacity conducting plate is connected to the refrigerator, the high-temperature superconducting coil is installed on the cooling capacity conducting plate, the high-temperature superconducting tape is fixed to the cooling capacity conducting plate by the L-shaped machined part. An output end of the motor is connected to one end of the rotating shaft through the dynamic sealing device, the other end of the rotating shaft is rotationally connected to the bow-shaped epoxy resin machined part. The permanent magnet rotor disk is installed on the rotating shaft and rotates along with the rotating shaft.

A motor assembly that includes a motor having a motor casing, a rotatable shaft extending from said motor casing to a shaft length and a hub coupled to said rotatable shaft, the hub having a circumferential skid surface disposed immediately proximal to the motor casing and having a channel configured to seat a propeller, when a propeller is present, wherein a bending moment applied to the shaft through the hub results in the circumferential skid surface contacting said motor casing.

A fluid moving apparatus includes an electric motor having a rotor and a stator and a propeller. The rotor rotates relative to the stator on an axis to generate a rotational output. The rotational output is provided to the propeller to power the marine propulsion apparatus. The stator includes one or more coils configured to power rotation of the rotor. The one or more coils extend circumferentially around and can be coaxial on the axis. A portion of a housing of the motor extends into the aquatic environment to facilitate heat dissipation.

An assist mechanism includes: an electric motor in which a rotor has a magnet and a stator has a winding; a shaft-shaped member in which a worm engaged with a worm wheel is formed; and a coupling that couples an output shaft of the electric motor and the shaft-shaped member to each other. The smallest rotation order among rotation orders of the electric motor and a rotation order of the worm are prime to each other.

A power tool is provided with a tool housing, a support plate provided within the tool housing, a rear tool cap mounted on a rear end of the tool housing, and a brushless direct-current (BLDC) motor received within the housing. The motor includes a stator assembly having a stator core and stator windings, a front motor bearing supported by the support plate, a rear motor bearing supported by the rear tool cap, and a rotor including a rotor core and a magnet ring mounted around the rotor core. The rotor core defines an annular recess within which at portion of the front bearing and a portion of the support plate are located such that the a radial plane intersects the front bearing, the magnet ring, and the stator core.

A magnetic gear may include a stator, having a stator core having a plurality of teeth extending toward a rotation shaft and a plurality of coils wound around the plurality of teeth, a rotor, having a rotor core disposed inside the stator and fixed to the rotation shaft and a plurality of permanent magnets attached to the external surface of the rotor core, and a pole-piece unit, having a plurality of first pole pieces and a plurality of second pole pieces arranged radially about the rotation shaft between the stator core and the rotor core such that the plurality of first pole pieces and the plurality of second pole pieces are alternately arranged in a circumferential direction thereof.

Provided is a coil including first and second lead parts, and a winding part. The winding part includes first to n-th turns. The winding part includes first and second coil ends. The first lead part extends from the first turn to the n-th turn along an upper surface of the first coil end. The second lead part extends from the n-th turn. The first and second lead parts include respective ends that are equal in height from the upper surface of the first coil end when viewed from a radial direction, and are equidistant from the n-th turn when viewed from an axial direction.

A propeller-type propulsion system for aircraft, comprises a propeller, a plurality of electric motors comprising nested coaxial respective driveshafts, and a gearbox having an output shaft onto which the propeller is mechanically coupled, and an input shaft to which the coaxial driveshafts of the electric motors are mechanically coupled. As a result, the diameter of the propulsion system, in a plane perpendicular to the axis of rotation of the propeller, is reduced. This improves the aerodynamics and the fuel consumption of the aircraft.