Abstract: A multiple coil, multiple armature solenoid is disclosed. The solenoid has; multiple armatures slidably disposed on a common slip shaft, with separate coils disposed about the corresponding armatures. The conductor coils, through magnetic induction, displace the armatures through respective linear strokes along the slip shaft. By varying the stroke length of the various armatures, it is possible to use an armature that travels through a short stroke length to generate kinetic energy that is transferred through the slip shaft to actuate an armature that must travel through a longer stroke length. In this manner, the problem of a high breakaway force associated with a long stroke armature is resolved.

Abstract: A propeller having blades designed to achieve maximum thrust at lower static velocities in both forward and reverse pitch modes is disclosed. Each blade has a generous leading edge radius leading to an upper surface having positive camber and a lower surface having positive camber adjacent the leading edge and negative camber adjacent the trailing edge. Each blade also has a high thickness-to-chord ratio and lower span-to-chord ratio or aspect ratio. This thicker blade profile and aft loading leads to a more uniform pressure distribution and laminar airflow across the blade surface resulting in a higher coefficient of lift, increased blade life and reliability, and lower noise levels.

Abstract: An electric motor having a stationary shaft carrying two spaced-apart bearings rotatably supporting a rotor. The shaft has an axial bore communicating with a radial slot in the shaft. An elongated locking member extends from the bore, through the slot, and into operative engagement with one of the bearings. A plug within the bore holds the locking member in place. A collar surrounds the shaft in the region of the slot, the locking member fixing one end of the collar against said one of the bearings. A compression spring surrounding the shaft presses against both the collar and the other of the bearings. The bore merges with the slot along an inclined surface which guides one end of the elongated locking member through the slot as the locking member is advanced along the bore during assembly.

Abstract: A heat dissipator including a thermally conductive material having a face adapted to contact a semiconductor to be cooled, and a clip for engaging the body and resiliently clamping the semiconductor device against the contact face. The clip has at least one attachment element which, like the leads of the semiconductor device, projects beyond one edge of the dissipator body, the attachment elements being used to join the body and hence the semiconductor device to a support, such as a printed circuit board. The clip may be formed of a solderable material which is different from the material of which the body is formed. The clip may be a single length of bent spring wire, or piece of bent sheet metal.

Abstract: An electric motor having a stationary shaft carrying two spaced-apart bearings rotatably supporting a rotor. The shaft has an axial bore communicating with a radial slot in the shaft. An elongated locking member extends from the bore, through the slot, and into operative engagement with one of the bearings. A plug within the bore holds the locking member in place. A collar surrounds the shaft in the region of the slot, the locking member fixing one end of the collar against said one of the bearings. A compression spring surrounding the shaft presses against both the collar and the other of the bearings. The bore merges with the slot along an inclined surface which guides one end of the elongated locking member through the slot as the locking member is advanced along the bore during assembly.

Abstract: A stepper motor having a stator and a rotor, the rotor having a shaft formed with an axial bore. A pair of bearings carried by the stator rotatably support the shaft. A stud is fixed within the bore and has an enlarged head extending radially beyond the external contour of the shaft into axial alignment with at least part of one of the bearings. Engagement between the stud head and the bearing limits axial movement of the rotor with respect to the bearing.

Abstract: A rotor includes an annular hub for accommodating a motor shaft, a tubular permanent magnet around the hub and radially spaced from it, and an annular support between the hub and magnet, the support being bonded to the hub and magnet. The support, a single piece of thin sheet metal, has inner and outer tubular walls, joined at corresponding ends by a disc-shaped bridge.

Abstract: A stepper motor including a pair of annular stator plates each having a plurality of poles surrounding a central opening, the plates being fixed to each other in back-to-back relation, and a pair of annular stator cups each having a plurality of poles surrounding a central opening and a peripheral side wall. The stator cups are arranged over opposite faces of the joined-together stator plates with the poles of each stator cup interleaved with the poles of its respective stator plate. The peripheral edges of the stator plates are separated from each other to define a gap between them, and the free edges of the stator cup side walls are bent into the gap to mechanically join each stator cup to its respective stator plate.

Abstract: An accessory for use with a conventional door closer having a body for mounting on a hinged door or the door jamb and a spring biased rotatable shaft constantly urging the door toward a closed position. The accessory comprises a first member having a reaction plate fixed with respect to the door closer body, a second member, such as an externally splined ring, fixed with respect to the door closer shaft, and a member, such as a flanged collar, rotatably interconnecting the first and second members. The collar is threaded into a hole in the reaction plate, and has an internally splined hole accommodating and meshing with the splined ring. The force of frictional engagement between the flange and the reaction plate progressively increases as the door is opened, and at an adjustable predetermined open position of the door the frictional resistance between the flange and reaction plate is stronger than the closing force of the door closer, so that the door is held open.

Abstract: A propeller having blades, designed to achieve maximum thrust at lower static velocities in both forward and reverse pitch modes is disclosed. Each blade has a generous leading edge radius leading to an upper surface having positive camber and a lower surface having positive camber adjacent the leading edge and negative camber adjacent the trailing edge. Each blade also has a high thickness-to-chord ratio and lower span-to-chord ratio or aspect ratio. This thicker blade profile and aft loading leads to a more uniform pressure distribution and laminar airflow across the blade surface resulting in a higher coefficient of lift, increased blade life and reliability, and lower noise levels.