Abstract: An improved control method activates an electric motor to drive a torque-to-thrust converter for controlling the torque capacity of a clutch mechanism. The control utilizes a model-based feed-forward control in combination with a closed-loop position feed-back control. The desired clutch torque capacity is characterized in terms of a desired motor position, and the feed-forward control models the motor speed and position response to changes in the desired motor position. The modeled speed and position, in turn, are used to create a feed-forward command, and the feed-forward command is combined with a feedback command based on actual position error.

Abstract: In an engine starter of the present invention, a driving shaft to output a rotating force and a crankshaft of an engine are linked continuously. The engine starter comprises a one-way clutch to prevent an overrun of an armature after the engine starts. In the one-way clutch, a connecting rotation number in which an inner ring and an outer ring change from a disconnected state to a connected state in a decreasing process of engine revolutions is set above a lower limit of the engine revolutions above which the engine under suspension of the fuel supply is able to get restarted by itself by resuming of fuel supply. Therefore, the engine is always able to get restarted quickly even in a low-rotation range.

Abstract: A drive system includes a hydrodynamic coupling device having a housing assembly, which is to be connected to an input shaft for rotating therewith, and an output element, which is to be brought into drive connection with a transmission arrangement. The hydrodynamic coupling device also comprises an electric machine equipped with a rotor assembly, which is connected to the housing assembly for rotating therewith, and with a stator assembly, wherein the stator assembly is supported on a housing that surrounds the hydrodynamic coupling device at least in areas. The area of the housing which supports the stator assembly has a cooling medium channel arrangement.

Abstract: A motor drive is constructed to include a DC motor, the DC motor having a worm at the output shaft thereof, a speed reducing mechanism formed of a main shaft and worm gear meshed with the worm and axially slidably mounted on the main shaft, a clutch adapted to control engagement between the main shaft and the worm gear, a mechanical step counter adapted to control forward/backward rotation of said DC motor, and an electronic step counter adapted to detect the pulse of the DC motor and to calculate the time to control forward/backward rotation of the DC motor.

Abstract: A magnetostrictive motor is provided with a pair of clutch devices on a rotor shaft through which electrical energy from electromagnetic rings on a tubular reactor is converted into forces transferred to the rotor shaft within the reactor under selective control of magnetostrictors and clutches within the tubular reactor to either accelerate or decelerate motion imparted by such forces to the rotor shaft for change of rotor speed magnitude and direction.

Abstract: An integrated motor and clutch assembly is provided, which includes a housing that rotatably supports an input shaft and an output shaft. A selectively engageable friction clutch is disposed between the input shaft and the output shaft for transferring torque therebetween. The friction clutch includes an outer hub connected for rotation with the output shaft. The integrated motor and clutch assembly also includes a motor having a rotor non-rotatably connected to the outer hub of the friction clutch and disposed coaxial with the input and output shafts. The motor also includes a stator secured to the housing and disposed concentric with the rotor.

Abstract: A housing of a compressor supports a rotary shaft. The rotary shaft is coupled to a pulley with a pulley one-way clutch and is coupled to a rotor of an electric motor with a motor one-way clutch. The pulley is supported by the housing with a pulley bearing. The electric motor overlaps a power transmission portion in the axial direction of the rotary shaft. At least two of the bearing, the pulley one-way clutch, the motor one-way clutch, and a brush device of the electric motor overlap each other in the axial direction of the rotary shaft. As a result, the size of the compressor is reduced in the axial direction of the rotary shaft.

Abstract: A clutch is arranged between a rotatable shaft and a worm shaft in a motor. The clutch includes a driving-side rotator connected to the rotatable shaft, a driven-side rotator connected to the worm shaft, a spring support and a coil spring arranged in the spring support. When the driving-side rotator is rotated upon energization of the motor, the coil spring is wound by the driving-side rotator to reduce an outer diameter of the coil spring, so that the rotation of the driving-side rotator is transmitted to the driven-side rotator and the worm shaft. When the driven-side rotator is rotated by an external mechanical force, the coil spring is unwound by the driven-side rotator to increase the outer diameter of the coil spring, so that a frictional force between the spring support and the coil spring is increased to restrain rotation of the driven-side rotator.

Abstract: A stator has a pocket portion (8) of a notch type resin-made stator, in which strength of an outer corner R (12b) provided in the pocket portion (8) is increased to thereby prevent the resin-made stator body (1) from being broken from the outer corner R (12b). A stator has a pocket portion (8) encasing a strut 9 of a notch type one-way clutch (5). The pocket portion (8) is provided in a stator body (1) made of resin, and corner Rs (12a, 12b) are provided on both inner and outer sides of a strut engaging surface (13) in the pocket portion (8). The outer corner R (12b) is formed to be larger than the inner corner R (12a).

Abstract: A starter motor assembly is provided. A motor housing encloses an electrical motor having a rotatable armature shaft. A rotatable drive shaft is provided that is engageably linked with the armature shaft. A pinion assembly is also provided, which includes a pinion that is engageable with the drive shaft for turning a flywheel of an engine. A solenoid assembly is provided, which includes a plunger. The plunger, when the solenoid assembly is energized, is moved in an axial direction to close electrical contacts to start the electrical motor and to move the pinion into engagement with the engine flywheel. Once the engine is cranked and the solenoid is deenergized, a return spring moves the pinion away from engagement with the engine flywheel. The return spring of the present invention moves the pinion without utilizing contact between the spring and the pinion (or any pinion shaft) to move the pinion away from engagement.

Abstract: A clutch includes a stopper secured to a gear housing of a motor. Once the stopper is secured to the gear housing, the stopper restrains axial movement of rolling elements by restraining axial movement of a support member, which rotatably supports the rolling elements, to retain the rolling elements within a collar. A driven-side rotator of the clutch includes reinforcing ribs for reinforcing engaging projections of the driven-side rotator.

Abstract: A gyroscopic stabilization and power management system that may be incorporated into a plurality of different devices. The system includes a flywheel, a motor centrally disposed within the flywheel such that the motor housing and flywheel rotate together when the motor shaft is fixed against rotation. A plurality of batteries or other power sources are radially disposed and integrated into the flywheel. The batteries increase the overall mass of the flywheel, thereby increasing its gyroscopic operation during rotation, in addition to providing power to the motor for operation. A printed circuit board connected to the flywheel handles all electronic controls both internal and external to the flywheel, including, for example, power control, speed control, electrical/mechanical power management, dynamic braking and radio controls.

Abstract: A driving-side rotator of a clutch has a connecting hole, within which a connecting portion of a rotatable shaft is loosely fitted while providing a space between the connecting hole and the connection portion. The connecting hole of the driving-side rotator is engageable with the connecting portion of the rotatable shaft in a rotational direction to integrally rotate with connecting portion of the rotatable shaft. Two positioning holes are provided in a brush holder, and two positioning projections are provided in a gear housing to allow direct positioning of the brush holder and the gear housing relative to each other.

Abstract: A high power and high torque density piezoelectric axial pump is developed using torsional actuator tube (stator) directly coupled to the rotor via two one way clutches. A cylindrical torsional actuator is comprised of a plurality of tubular piezoelectric ceramic segments poled along their length, aligned in alternate polarity and bonded together with intervening electrodes. When an alternating electric field is applied to the electrodes across adjacent segments to actuate the segments in their shear resonance mode, an end of the cylindrical actuator moves in a direction perpendicular to the length of the actuator in response to the applied electric field. This full cycle pump two sets of one way clutches positioned at the other end of the cylindrical actuator tube such that both ends of the tube move in opposite angular directions.

Abstract: The rolling bearing with a built-in motor includes a bearing part including an inner ring, an outer ring and a plurality of rolling elements, and a motor part including a stator and a rotor for driving and rotating the inner and outer rings of the bearing part with respect to each other. In the rolling bearing, the bearing part includes a first bearing ring having a cylindrical-shaped inner fixing portion formed in one end face of the inner ring so as to be coaxial therewith, and a second bearing ring having a cylindrical-shaped outer fixing portion formed in one end face of the outer ring so as to be coaxial therewith. When viewed in the radial direction of the rolling bearing, the stator and rotor are interposed between the inner fixing portion of the first bearing ring and the outer fixing portion of the second bearing ring.

Abstract: In a clutch, when a driving-side rotator is rotated, the driving-side rotator engages a driven-side rotator in a rotational direction and transmits a rotational force of the driving-side rotator to the driven-side rotator. When the driven-side rotator is rotated by an external force, a rolling element is clamped between the driven-side rotator and an inner circumferential surface of a housing. At the same time the driven-side rotator is allowed to rotate while generating a desired frictional force between the rolling element and the inner circumferential surface of the housing, so that the rotation of the driven-side rotator is not transmitted to the driving-side rotator.

Abstract: A drive system for a motor vehicle includes a drive shaft with a flywheel mass arrangement provided thereon, an electric machine for driving the drive shaft and/or obtaining electric energy from the rotating drive shaft. The electric machine has a stator arrangement and a rotor arrangement which can be rotated by the drive shaft. The rotor arrangement is connected via the flywheel mass arrangement to the drive shaft. Furthermore, the rotor arrangement is connected to the flywheel mass arrangement via a connecting region having a higher resistance to thermal conduction than at least one of the regions that adjoins the connecting region.

Abstract: A clutch includes an outer ring, a driving-side rotator, a driven-side rotator and rolling elements. Each rolling element is located between an inner circumferential surface of the ring and a corresponding control surface of the driven-side rotator and has a diameter shorter than a distance between a circumferential center portion of the control surface and the inner circumferential surface of the ring but longer than a distance between each of opposing circumferential end portions of the control surface and the inner circumferential surface of the ring. The center portion is located radially outward of a straight line that connects the end portions. Each intermediate portion positioned between the center portion and the end portion is arcuately bulged beyond a straight line that connects the center portion and the end portion.

Abstract: A notched type one-way clutch (11) has a strut (8) which is accommodated, together with a spring (9), within a pocket portion (7) formed in a resinous stator body (1) and also has a notched plate (6), the notched plate (6) being combined with the stator body (1) in a relatively rotatable manner and provided with an engaging recess (10) with which the strut (8) comes into engagement in one rotational direction. A swing angle limiting portion (12) for limiting a swing motion of the strut (8) up to a predetermined angle is formed in the pocket portion (7). Further, a movement limiting portion (14) for limiting the movement of the strut (8) toward an anti-engaging face (7b) side within the pocket portion (7) is formed on an engaging face (7a) side of the swing angle limiting portion (12) integrally by molding.

Abstract: A permanent magnet coupler has a conductor rotor assembly mounted on one shaft and a magnet rotor assembly mounted on a coaxial shaft. The magnet rotor assembly provides two magnet rotors spaced by the adjustable air gaps from two conductor elements provided by the conductor rotor assembly. The air gap adjustment includes adjustable stops, such, for example, as swing arms having an adjustable effective length. These stops operate in conjunction with swing arms causing the magnet rotors to move axially in unison in opposite directions. The air gaps are set so that the coupler will automatically release when subjected to an overloaded condition.

Abstract: A self powered lock is powered by a manually driven generator. The data input to the lock is entered by rotating the dial and stopping and waiting a predetermined amount of time when a desired number is displayed on the lock display. The drive of the power generator, a stepper motor, is through a unidirectional clutch, such that the generator is only driven when the dial is rotated in a selected direction and remains stationary when the dial is rotated in the opposite direction. The data input, including entry of the combination, to the lock is provided by a stepper motor which generates a train of electrical pulses. The electrical pulses are used by the electronic controls of the lock to control the electronic controls including entering the combination. The data input pulses are generated by a stepper motor driven to act as a generator.

Abstract: An automotive AC dynamo-electric machine is capable of providing a sufficient rotational output for starting an engine by running a rotor at high speed in a motor operation mode for starting the engine, thus obviating the need for increasing a size thereof. In the motor operation mode, an electromagnetic clutch follower connects to an electromagnetic clutch main body and also engages a cylindrical member to brake the cylindrical member. An internal gear portion provides a fixed element, and torque of a rotor is transmitted to a power transmission device via a rotor shaft, a sun gear, a planetary gear, and a carrier.

Abstract: To secure sufficient attractive force against a plunger, an overrunning clutch is arranged so that one end of a thrust spline is positioned so as to maintain a prescribed interval from the end of the plunger in the condition where the plunger is unexcited by an exciting coil and the outside periphery of the output shaft corresponding to the prescribed interval is covered by a cylinder body formed of a non-magnetic material or less permeable material.

Abstract: A drive arrangement for a motor vehicle, which has at least one internal combustion engine and a down-line clutch, via which the internal combustion engine can be connected to an output drive shaft. An electric machine is provided and includes a rotor and a stator, wherein the rotor can be coupled to a drive train formed by the internal combustion engine, the clutch and the output drive shaft by at least one switchable interlocking device.

Abstract: A motor used in a power window system includes a motor section, a warm-gear included output section and a one-way clutch. The one-way clutch is disposed between a motor's shaft and a worm's shaft. The one-way clutch includes a drive member having at least a pair of guide surfaces, driven member coupled with the drive member, a stationary housing, and a rotary member disposed between the driven member and the stationary member and between the pair of guide surfaces. The motor and the one-way clutch has a common member fixed to both the motor and the one-way clutch.

Abstract: An AC generator for charging a vehicle battery has a stator having a stator winding, a rotor having a field coil and auxiliary permanent magnets, a pulley, and a clutch disposed between the pulley and the rotor. The clutch limits rotation speed to be transmitted from the pulley to the rotor within a set rotation speed.

Abstract: A device for attachment of electrical equipment, such as an alternator/starter motor, in the clutch housing of an automobile. The assembly includes a stator, a rotor, and a support hub of the rotor mounted on a bearing in an independent housing integral with the clutch housing.

Abstract: The invention relates to a hysteresis brake comprising a hysteresis ring (1) which is rotationally fixed to a roller (9), and a magnetic ring with magnetic poles. The magnetic ring (2) is made of permanent magnetic material and is mounted inside the hysteresis ring (1), wherein the magnetic poles are alternately along the external circumference of the magnet ring (2). The magnetic ring (2) encloses a supporting member (4), which is mounted in a rotationally secured position but which can be axially displaced around the axis by means of a regulating device (7).

Abstract: A motor includes a motor section, a one-way clutch and an output section. The motor section includes an armature and armature shaft, and the output section includes a worm mechanism having a worm shaft disposed coaxially with the armature shaft. The one-way clutch is disposed between the armature shaft and the warm shaft. The one-way clutch includes a couple of teeth members in engagement with each other, a plurality of rollers for controlling the teeth members, and a spring holding the rollers. The spring urges the worm shaft to separate from the armature shaft.

Abstract: A drive arrangement for a motor vehicle includes an internal combustion engine with a crankshaft which is selectively connectable to an output drive shaft via an interposed clutch system. The clutch system has at least two flywheel masses which are rotatable relative to each other. A first flywheel mass comprises at least one primary flange which is permanently connected to the crankshaft. The clutch system also includes an electric machine which has a rotor with a rotor carrier, the electric machine being arranged in the clutch system so that the primary flange is part of the rotor carrier.

Abstract: A motor/generator unit applicable to an automotive vehicle is disclosed. The motor/generator unit includes: a torque converter (102a) to perform a transmission of a driving force between an output axle of a vehicular engine and an input axle of a transmission, the transmission being enabled to switch between a neutral state and a forward-and-rearward state and being enabled to vary a gear ratio; a housing (5) enclosing a periphery of the torque converter; a hydraulic clutch; an electromagnetic clutch, both (102c) of the hydraulic clutch and electromagnetic clutch being juxtaposed to be enabled to form a lock-up state of the torque converter; and amotor/generator (102b) including a stator (1) fixed to the housing and a rotor (8) attached to a rotary element of the torque converter so as to be opposed to the stator, the motor/generator being disposed to be enabled to give and receive a torque to and from the rotary element of the torque converter.

Abstract: An electromagnetic coil is disposed in a rotor, and electrically insulated from the rotor. A slip-ring is supported by a rotor through a slip-ring supporter, and rotates with the rotor. A brush is supported by a compressor boss portion through a brush supporter, and supplies an electric current to the slip-ring. A diode is disposed in the brush supporter or the slip-ring supporter, and absorbs a surge voltage which is inducted when said electromagnetic coil is disenergized.

Abstract: A cylinder of a rotary printing press is provided with a journal which is supported for rotation in an eccentric bushing. The eccentric bushing is, in turn, shiftably positioned in a lateral side frame of the printing press. The cylinder is directly driven by an electric motor. This electric motor is mounted directly on the eccentric bushing. A compensation coupling, such as a clutch is placed between the electric motor and the cylinder.

Abstract: A cage carrying two axially adjustable conductors is mounted on one shaft and a rotor is mounted on a second coaxial shaft to occupy a position between the conductors. Permanent magnets on the rotor have poles spaced by air gaps from the conductors. The air gaps are adjusted by sliding the conductors toward and away from one another along slide members on the cage by use of adjustment units engaging the conductor rotors. Alternatively, the conductors can be mounted on the rotor, and the magnets can be adjustably mounted on the cage.

Abstract: A starter comprising: a motor 24, a clutch 21, which is connected to the motor 24; a pinion gear 22, which is connected to the clutch 21 and engages and disengages with the ring gear of the engine; an electromagnetic switch 2, which switches on and off an electric current for the motor 24; a reciprocating shift lever 4, which is linked to the electromagnetic switch 2; and lever springs 105, which press the shift lever 4 so that the pinion gear 22 is elastically pushed against and engaged with the ring gear; wherein the lever springs 105 are arranged symmetrically with respect to a plane 25 which includes the central axis of the motor 24 and the central axis of the electromagnetic switch 2, the lever springs 105 are attached to cylindrical portions 106b which are a plurality of protrusions on the plate 106, and the lever springs 105 and the shift lever 4 come into contact through a plate 106.

Abstract: A compact, inexpensive electromagnetic spring clutch includes forming supporting bearing surfaces made of synthetic resin rotary members, in a magnetic excitor. Cylindrical magnetic pole parts are formed in the first core and second core and the inner surfaces of these magnetic pole parts are made into bearing surfaces.

Abstract: An electric motor assembly includes an output shaft with a fixed large gear, a driving shaft with a fixed small gear, a motor for rotating the driving shaft, and a gear box. The gear box includes a housing and a reduction gearing, which is disposed within the housing. The gearing includes a plurality of speed-reducing members, each of which includes a rotating shaft journalled in the housing, a large gear sleeved fixedly on the rotating shaft, and a small gear sleeved fixedly on the rotating shaft and with a tooth number and a diameter that are smaller than those of the large gear. The large gears of the output shaft and the speed-reducing members mesh respectively with the small gears of the driving shaft and the speed-reducing members. One of the large and small gears of the speed-reducing members has a side surface.

Abstract: A valve actuating apparatus is provided for operating a valve between an open and closed position. The valve actuating apparatus includes an actuator having an output member with the actuator providing reciprocating motion to the output member upon energization of the actuator. A guide member having a detent therein is connected to the output member of the actuator. The apparatus includes a clutch assembly having a housing, an electromagnet assembly, an engagement member, and a housing opening with the engagement member disposed in the housing between the electromagnet assembly, and the housing opening. The housing opening is adapted to receive the guide member therein such that the clutch assembly and a portion of the guide member are slidably connected. The electromagnet assembly is selectively energized to force the engagement member against the guide member disposed in the housing opening.

Abstract: A magnetic coupling device has an electroconductive rotor presenting a band of electroconductive material and has a magnet rotor with permanent magnets which may be slide-mounted to move radially outward responsive to centrifugal force in opposition to a spring bias. When the magnet rotor is stationary the magnets are radially inward of the orbit of the electroconductive band, and when the magnets have moved outwardly when the magnet rotor is rotating, the magnets are spaced by an air gap from the electroconductive band so that eddy currents are induced in the band resulting in coupling of the rotors. In the alternative the magnets may be always at least partly opposite the electroconductive band. The electroconductive rotor preferably has two electroconductive bands positioned on opposite sides of the magnet rotor. One or both of the rotors may have sheaves mounted thereon.

Abstract: An adjustable coupler has a group of magnet rotors separated by air gaps from a group of conductor rotors. The air gaps are adjusted by axial movement of one of the groups relative to the other to vary the slip of the coupler and achieve a constant load speed at various load torques.

Abstract: A motor for motorcycles includes a shaft, a rotor, an inner housing covering the rotor, a sun and planet gear unit, a generator, an outer housing, and a clutch as main components. The generator produces electricity to charge a battery when the motor moves the motorcycle so that the battery is always fully charged for operating the motor. The clutch will not engage a wheel of the motorcycle to rotate until rotation of the motor reaches a preset speed.

Abstract: An electric machine which can be operated optionally as a motor or generator and in particular can be installed in the drive train of a motor vehicle with a hybrid drive. The machine includes a stator and a rotor of substantially cylindrical shape, The rotor is positioned about the stator to form a circumferential air gap between the stator and the rotor. An integrated switchable clutch is provided for the transmission of torque. The rotor is arranged on the outside (external-rotor machine) of the stator and the clutch is arranged within the stator.

Abstract: To make the turning "on" and "off" of a clutch in an electro-magnetic clutch smoother, the electro-magnetic clutch has a first rotating member rotatable in response to the driving force applied to the input axis, and a second rotating member arranged opposite to the first rotating member and freely rotatable about the rotation axis of the first rotating member and coupled to the output axis. A movable member is coupled to one end of a return spring and is disposed between the first rotating member and the second rotating member for movement along the rotation axis of the first rotating member. An electric coil generates a force to drive the movable member along the rotation axis of the first rotating member. Cylindrical auxiliary slide members are arranged approximately at equal intervals on the movable member and are disposed between the movable member and the second rotating member.

Abstract: A bi-stable clutch is introduced comprising an input and output shaft, a hub assembly attached to output shaft, a hub assembly attached to output shaft and operatively associated with a friction ring which rotates with output shaft of the unique bi-stable clutch. The input shaft is connected to a rotor which drives an armature plate to which the rotor is rotatably attached. The rotor and armature plate are forced apart when the clutch is engaged creating an air gap between the two large enough to not be overcome by the permanent magnet field attracting the armature plate due to a force caused by compression coil springs and the armature plate remains in contact with the rotor and the clutch remains engaged without continuous current transmitting torque from the input to the output shaft.

Abstract: An electric motor which is capable of changing an output torque with a simple arrangement without using an expensive power unit for controlling the supply of voltage (current) to an armature. The electric motor has a motor section constituted by an armature, a first pole piece, and a second pole piece, and has a slide bevel gear which meshes with a bevel gear of an input shaft. The slide bevel gear moves in an axial direction in correspondence with the steering torque, which movement is transmitted to the second pole piece by a pressing lever to rotatively move the second pole piece. Consequently, the opposing positions of poles of the first pole piece and the second pole piece are relatively changed to change polarities, so that a driving force corresponding to the steering torque is outputted.

Abstract: Disclosed herein is a compact motor with a speed reducing mechanism, including a cylindrical casing having an open end, a stator fixedly provided in the casing, an exciting coil provided in the casing, a rotor provided in the casing and having a high-speed output shaft on which a pinion is fixed, a cover for covering the open end of the casing, a low-speed output shaft projecting from a hole formed through the cover, and a reduction gear train interposed between the pinion and the low-speed output shaft for transmitting power to the low-speed output shaft. The compact motor further includes a lever connected to the low-speed output shaft; an eccentric cylinder formed integrally with a final gear of the reduction gear train and adapted to eccentrically rotate about a gear shaft for rotatably supporting the final gear; and a connecting member having one end pivotally engaging with an outer circumference of the eccentric cylinder and another end pivotally engaging with the lever.

Abstract: An electric motor drive unit for surgical tools, in which a drive consisting of a motor or motor gear unit is connected to, and electrically insulated from a clutch for the tool by a shaft, and in which the drive as well as current-carrying components are electrically insulated from a housing which accomodates said drive and current-carrying components. To achieve an electrical isolation of the current-carrying components from the tool and the gripping surface of the housing, the shaft, at least over part of its length, is made from an insulating material and runs through a seal which is supported in the housing and sealingly divides the housing into a first and second chamber, of which the first chamber accomodates the drive and the second chamber accomodates the clutch for the tool, said tool being inserted into a distal opening in the housing in the second chamber and connectable to the clutch.

Abstract: A conductor rotor presents a pair of electroconductive rings spaced apart to receive magnet carrying shoes with permanent magnets to induce eddy currents in the rings and thereby retard rotation of the conductor rotor. The shoes are moved in and out in a controlled manner to move between a retracted brake-off position and an extended brake-on position.

Abstract: A power transfer assembly has a magnet rotor with permanent magnets co-acting with a pair of electroconductive rings on a conductor rotor. The rotary axes of the two rotors are in laterally spaced parallel relation with one of the rotors being greater in diameter than the other.

Abstract: A multi-rotor A.C. electric drive device comprises a stator capable of producing a rotating or an alternating magnetic field and at least two rotors capable of producing an electromagenetic torque at asynchronous speed. The rotors are respectively called the main rotor and the auxiliary rotors. In low speed operating mode of said device, the electromagnetic torque of the auxiliary rotor is amplified through a transmission portion and drives an output element together with the main rotor; after the auxiliary rotor is accelerated to the synchronous speed, an automatic unloading device releases the auxiliary rotor from the driving engagement with the output element. Examples illustrating several types of electromagnetic portion, transmission portion and the automatic unloading device are given.