Abstract: In an electric motor of an SBW actuator, a rotor shaft is rotated upon energization of the motor. A rotor core is rotated integrally with the rotor shaft. A resilient member enables tilting or decentering of the rotor shaft upon application of a decentering force on the rotor shaft. A stator core contacts the rotor core when the rotor shaft is tilted or decentered.

Abstract: Machine for contactless fixing of a movement degree of freedom, having a primary part and a secondary part, wherein the primary part and the secondary part are designed such that a cogging force when no current is flowing in the machine is at least 50% of the maximum force of the machine.

Abstract: A no-back device for a power drive unit is configured such that, during operation of the power drive unit, the no-back device does not supply magnetic or frictional force against power drive unit rotation. The no-back device is implemented either redundantly or no-redundantly, and includes a latch rotor and an electromagnet. In both embodiments, the latch rotor is coupled to the power drive unit to rotate therewith, and the electromagnet is coupled to receive a flow of current and, upon receipt thereof, generates a magnetic field force that opposes rotation of the latch rotor. In the redundant embodiment, the no-back device further includes one or more permanent magnets, and the magnetic field generated by the electromagnet selectively opposes or aids the magnetic field supplied by the permanent magnet(s).

Abstract: A spool includes at least one bobbin and one winding wire, e.g., a winding wire lacquered for electrical insulation, the bobbin including at least one channel, e.g., one arranged as a pocket, at least one sleeve being electrically connected to the winding wire, the sleeve being electrically connected to an electrical line, e.g., a stranded conductor of a cable, the sleeve including deformable regions, for producing the electrical connections, a respectively deformable region being deformable such that a force-locking connection is provided and welding is able to be carried out.

Abstract: The present invention provides a magnetic wheel including a foundation body, a cover body, a fly wheel, a central axis, a drive motor, a drive gear assembly and two magnetic control strips. The drive gear assembly is driven by an output axis of the drive motor, enabling the swinging of the gear wheel of two magnetic control strips. The drive gear assembly has a gearshift unit, a coupling element and rear gear. The axial direction of the coupling element and rear gear is the same as the central axis of the magnetic wheel. The gear wheel of two magnetic control strips is mated with the rear gear through spur gear, thus making it easier to improve the manufacturing precision and drive efficiency and also reduce the manufacturing cost for better economic efficiency.

Abstract: A plurality of fan blades are secured to a rotor assembly of a single directional motor. When the motor is powered on, a force generated by the fan blades pushes the rotor assembly in a direction of a low friction thrust interface. When the motor is backdriven in a direction opposite the powered direction, the force generated by the fan blades pushes the rotor assembly in a direction of a higher-friction thrust interface, causing a tapered surface of the pinion and a tapered surface of a bearing retainer to be pressed against each other to produce a frictional braking force. The backdriven speed of the motor and drive device is therefore reduced, improving the reliability of the motor assembly. The invention can be applied to motor actuators used to control air dampers and other valves in gas or fluid delivery systems. The invention can also be used to reduce water hammer in water delivery systems.

Abstract: A rotational coupling device for use as a clutch and/or brake is provided having improved magnetic efficiency and structural integrity. A permanent magnet is coupled to one of a brake plate and an armature and axially aligned with a portion of the other for improved braking performance.

Abstract: An actuator. In one embodiment, the actuator comprises a reversible electric motor having a stator having a housing, a rotor housed in the housing of the stator, and a shaft having a forward portion and a rearward portion extending oppositely and coaxially from the rotor, respectively; a fan member coaxially attached to the forward portion or the rearward portion of the motor shaft such that the fan member is operable simultaneously with the rotor of the reversible electric motor; and an electromagnetic brake movable between a first position and a second position, positioned in relation to the fan member such that when the electromagnetic brake is in the first position, the fan member is rotatable with the rotor of the reversible electric motor, and when the electromagnetic brake is in the second position, the fan member stops rotating firmly, thereby causing the motor stops instantly.

Abstract: A direct drive torque motor comprises: a body, a direct drive torque motor, a main shaft, a bearing assembly, a brake assembly, a cooling assembly, and a position-sensing assembly. The bearing assembly is used to position the main shaft in the direct drive torque motor and the body. The brake assembly is disposed between the body and the main shaft. The cooling assembly is located in the body to cool the torque motor. The position-sensing assembly is mounted on the body for sensing the rotation of the main shaft and then controls the drive of the direct drive torque motor. With above arrangements, the direct drive torque motor can be used on various machines that need to rotate to perform various angle control, rotation control and accuracy control, it can improve the life and the modular application of the product.

Abstract: The invention relates to a device for damping the movement of a movable element (1) relative to a fixed element (3). The device comprises means for generating an electric current changing with the speed of movement of the movable element (1) relative to a fixed element (3). According to the invention, the device also comprises means (20 to 25) for modifying the mechanical properties of a fluid situated between the movable element (1) and the fixed element (3) by means of the electric current. The means (4 to 7, 8, 10) for generating an electric current comprise a generator comprising a rotor (4 to 7) and a stator (8, 10), the rotor (4 to 7) being fixedly attached to the movable element (1) and the stator (8, 10) being fixedly attached to the fixed element (3). Advantageously a magnetorheological fluid, bathed in a magnetic field generated by the electric current, is used.

Abstract: A braking device for an electrically driven rotor comprises a drive signal generating circuit for an electrically driven rotor, an output stage, a motor for the electrically driven rotor, driven by the output stage, and a monitor circuit for detecting interruption of an electric power supply for the motor. The output stage has a MOSFET of an upper stage side and a MOSFET of a lower side, and a diode inserted between a gate of the MOSFET of the lower stage side and the electric power supply. An electromagnetic brake is generated and applied on the electrically driven rotor when the MOSFET of the upper stage side is turned OFF and the MOSFET of the lower stage side is turned ON by a control signal from the monitor circuit, and an exciter coil of the motor is shorted when the electric power supply is interrupted.

Abstract: A deflector for an electromagnetic retarder including a rotary shaft with a fan for circulating a cooling gas to the induction coils which are intended, upon command, to generate Foucault currents in a stator surrounding the rotary shaft and the induction coils. The inventive deflector (1) includes a body (2) which is provided with at least one return face (3), known as the radial return face, which is intended to release the gas radially from the retarder, said body (2) being shaped such that the deflector (1) can be disposed non-rotatably and coaxially in relation to the shaft of the retarder.

Abstract: A motor for driving a movable body includes a cylinder portion that holds a field magnet, a coil holder disposed rotatably to the cylinder portion, a conducting coil wound on the coil holder and generates a rotational force between the same and the cylinder portion when a current flows in the conducting coil, a brake coil provided on the coil holder, where an electromotive force for generating magnetic field that suppresses relative rotation between the coil holder and the cylinder portion is induced between both ends of brake coil when a current flows in the conducting coil, and a switch interposed between the both ends of the brake coil.

Abstract: The present invention relates to an electromechanical motor (M) provided with an actuator (A) having an outer casing (30-30?-30?) surrounding a stator (20-20?) possessing a coil (24). The rotor (10) is also disposed inside the stator (20-20?). The invention is remarkable in that the actuator has two distinct and independent outlets (S1, S2) capable respectively of actuating, one after the other, first and second transmissions (C1, C2).

Abstract: In an electric motor of an SBW actuator, a rotor shaft is rotated upon energization of the motor. A rotor core is rotated integrally with the rotor shaft. A resilient member enables tilting or decentering of the rotor shaft upon application of a decentering force on the rotor shaft. A stator core contacts the rotor core when the rotor shaft is tilted or decentered.

Abstract: An actuator. In one embodiment, the actuator comprises a reversible electric motor having a stator having a housing, a rotor housed in the housing of the stator, and a shaft having a forward portion and a rearward portion extending oppositely and coaxially from the rotor, respectively; a fan member coaxially attached to the forward portion or the rearward portion of the motor shaft such that the fan member is operable simultaneously with the rotor of the reversible electric motor; and an electromagnetic brake movable between a first position and a second position, positioned in relation to the fan member such that when the electromagnetic brake is in the first position, the fan member is rotatable with the rotor of the reversible electric motor, and when the electromagnetic brake is in the second position, the fan member stops rotating firmly, thereby causing the motor stops instantly.

Abstract: A method for controlling an electromagnetic retarder from a control unit said retarder including an electrical generator. The inventive method is used to determine an excitation current intensity to be injected into the primary coils of the generator of the retarder, said retarder including a rotary shaft bearing the secondary windings of the generator a n d field coils which are supplied b y the secondary windings. The rotation speed of the rotary shaft is taken into account in order to select a lower intensity if the rotation speed of the shaft is higher. The invention is suitable for use in the field of electromagnetic retarders which are intended for heavy vehicles such as trucks.

Abstract: A motor that delivers high force linear motion or high torque rotary motion to a moving element. The motor may include a driving brake, a driver, a holding brake and a flexible moving element. Operation of the motor may involve activating the holding brake, activating the driver to flex the moving element, activating the holding brake to maintain the position of a portion of the moving element, releasing the driving brake, and restoring the moving element to an unflexed position. The elements are arranged to provide linear motion, belt-driven rotary motion, or directly-coupled rotary motion using brakes and drivers arranged in linear or circular fashion. Drivers may be linear or rotary actuators or motors based on electrostatic, piezoelectric, magnetic, or electrostrictive properties. The brakes may be applied through electrostatic forces, magnetic forces, or mechanical gears engaged with a linear or rotary driving mechanism.

Abstract: A plurality of fan blades are secured to a rotor assembly of a single directional motor. When the motor is powered on, a force generated by the fan blades pushes the rotor assembly in a direction of a low friction thrust interface. When the motor is backdriven in a direction opposite the powered direction, the force generated by the fan blades pushes the rotor assembly in a direction of a higher-friction thrust interface, causing a tapered surface of the pinion and a tapered surface of a bearing retainer to be pressed against each other to produce a frictional braking force. The backdriven speed of the motor and drive device is therefore reduced, improving the reliability of the motor assembly. The invention can be applied to motor actuators used to control air dampers and other valves in gas or fluid delivery systems. The invention can also be used to reduce water hammer in water delivery systems.

Abstract: An electromagnetic brake (20), in particular for an electric drive is provided, having a brake body (3), which is provided with a sleeve-shaped permanent magnet (4), an electromagnet (5) with an exciting coil (6), an external ring in the form of an external pole and an internal ring (8) in the form of an internal pole, wherein an armature disc (12) rotatably connected to a shaft is attractable against the brake body (3) or the external or internal ring surfaces by the permanent magnet (4) force acting against a return spring force. When the exciting coil is powered, the permanent magnet (4) magnetic field is compensated in such a way that the armature disc (12) is lifted up from the brake body (3) by the spring force, thereby allowing the brake to be released.

Abstract: A drive for an adjuster device in a motor vehicle. The drive includes a drive motor, a drive element mounted to rotate about a drive axis, and a self-locking device for the drive element, which, when the drive motor is not energized, locks the drive element with the locking element. The locking element may be brought out of engagement with the drive element in the radial direction relative to the drive axis on energizing the drive motor.

Abstract: An electromagnetic retarder system is disclosed. In one embodiment, the retarder system comprises: a shaft; a coil statically disposed on the shaft and having a hollow cylindrical shape; a yoke statically disposed on the shaft, the yoke having a first cylindrical surface and a second cylindrical surface, the second cylindrical surface disposed coaxial with said coil; at least one claw pole rotor mounted on the shaft, the at least one claw pole rotor formed of magnetic half wheels that taper into claws; and an induction drum disposed coaxial with the shaft and mounted so as to encompass the coil, the yoke and the at least one rotor.

Abstract: A braking magnet is attached to the housing of a motor of a motorized component such as a window covering. With this structure the motor is braked from turning under the weight of the window covering when deenergized.

Abstract: A motor for driving a movable body includes a cylinder portion that holds a field magnet, a coil holder disposed rotatably to the cylinder portion, a conducting coil wound on the coil holder and generates a rotational force between the same and the cylinder portion when a current flows in the conducting coil, a brake coil provided on the coil holder, where an electromotive force for generating magnetic field that suppresses relative rotation between the coil holder and the cylinder portion is induced between both ends of brake coil when a current flows in the conducting coil, and a switch interposed between the both ends of the brake coil.

Abstract: A wheel hub drive for a running wheel (10) is described. The drive having a transmission (7), a motor (8) and a brake (11), such that the enveloping circle (9) of the wheel hub drive is determined by the running wheel and the transmission (7), motor (8) and brake are located within a circle whose radius is determined by the running wheel (10).

Abstract: A retarder (16), as a braking device or auxiliary braking device for vehicles or the like, in particular rail vehicles, is described, having a stator (3), comprising at least two axially spaced-apart stator halves (3a, 3b), which each have magnetic field coils, and a rotor which is disposed between the at least two stator halves (3a, 3b), the rotor being coupled in a manner fixed against relative rotation to an axle (5) or shaft of the vehicle and the stator being coupled with the vehicle, or a undercarriage (19) of the vehicle. The rotor is formed by at least one rotor disk (1) divided into two parts, comprising two adjacent rotor halves (1a, 1b), which are joined to one another in a radially inner annular region, oriented toward the axle (5) or shaft, and are disposed in a radially outer annular section (7a, 7b), with axial clearance from one another (FIG. 4).

Abstract: An electromagnetic retarder (1) for a vehicle includes a disc (20), a first rotor (5) and a second rotor (6), the disc being arranged to couple the first rotor and the second rotor to a transmission shaft of a vehicle. In order to facilitate fitting of this transmission shaft on the electromagnetic retarder, the invention provides for positioning the disc on one of the two rotors in such a way that the disc is placed in a position offset longitudinally, with respect to an axis (21) of the retarder, towards one of the two rotors. The disc includes fastening means for fastening the disc on the corresponding rotor, which fastening means (22) are such that they are positioned between curved arms (9, 10) of the rotor.

Abstract: A combination of a torque-generating apparatus with an alternator/generator. The torque-generating apparatus comprises a first assembly (10, 25) including a generally cylindrical member of magnetically soft material and having a longitudinal axis, and a second assembly (2) arranged coaxially within the first assembly and including an electromagnetic winding (4). The first assembly (10, 25) and the second assembly (2) are rotatable relative to each other about the axis. Relative rotation between the first (10, 25) and second (2) assemblies induces a magnetic field which generates rotational torque between the first and second assemblies. Rectification means (31) is provided to convert alternating current electrical output from the alternator/generator (22) to provide D.C. current to the electromagnetic windings (4) of the torque generating apparatus to generate an electromagnetic braking effect.

Abstract: A braking device for an electric motor includes a rotor (10) and a stator, in particular for a direct current series wound motor and a brake element (20) which is movable between a braking position and an operating position; a brake shoe (30) that brakes the rotor (10) in the braking position is mounted on the brake element (20). The brake shoe (30) is mounted on the brake element (20) on the trailing end relative to the direction of rotation of the rotor (10).

Abstract: An eddy current deceleration device comprises: a rotor mounted on a rotary shaft; a first magnet ring arranged facing this rotor and including permanent magnets that are arranged at prescribed intervals in the circumferential direction and such that the poles thereof facing each other in the circumferential direction are of a same polarity, and magnetic members interposed between these permanent magnets; and a second magnet ring arranged between this first magnet ring and the rotor and including permanent magnets and magnetic members which are similar to those of the first magnet ring; at least one of the first and second magnet rings being freely rotatable. The permanent magnets of the first and second magnet rings can be magnetized separately between the first and second magnet rings.

Abstract: A magnetic controlled loading device in combination of a power generating set and an adjusting drive mechanism having a flywheel, a shaft, a transmission element, a magnetic controlled loading device, a micro power generating set and an adjusting drive mechanism integrated into one single unit. It can also be taken apart and used in various combinations. By fully utilizing the limited space without increasing the volume of the flywheel and internal components, a rotor and a stator are disposed in the center of the magnetic controlled loading device. This makes the rotor's permanent magnets to be set on top of the flywheel's inner ring, so that when the flywheel is in operation, it turns into a micro power generating set. By utilizing its self generating power supply, it can provide the power needed by a small motor and by manual adjustments it can also control the changes in magnetic flux density between the flywheel and device as well to achieve continuous adjustment of loading resistance.

Abstract: Two braking magnets are attached to the housing of a motor of a motorized component such as a window covering, with one magnet north face down and the other magnet south face down. With this structure the motor is braked from turning under the weight of the window covering when deenergized, while during operation the average null value of the braking field results in minimal drag on the motor.

Abstract: A braking assembly with a manageable self-generating power energy is disclosed. A pair of curved braking plates are disposed between the stator and the rotor. A pulling mechanism is provided on the stator for pulling two free ends of two curved braking plates. A plurality of first permanent magnets are fixed to the outer circumferential surface of each the curved braking plates. Moreover, at least one power-generating coil is provided on a stator of the braking assembly nearby the permanent magnets for generating an AC voltage when the rotary central shaft rotates. A control circuit receives the AC voltage and rectifies and stabilizes the AC voltage to generate a DC voltages to drive the motor of the pulling mechanism to rotate, and by means of the pulling mechanism, the braking force of the braking assembly is controlled.

Abstract: An eddy current deceleration device includes a rotor mounted on a rotary shaft; a first magnet ring arranged facing this rotor and including permanent magnets that are arranged at prescribed intervals in the circumferential direction and such that the poles thereof facing each other in the circumferential direction are of a same polarity, and magnetic members interposed between these permanent magnets; and a second magnet ring arranged between this first magnet ring and the rotor and including permanent magnets and magnetic members which are similar to those of the first magnet ring; at least one of the first and second magnet rings being freely rotatable. The permanent magnets of the first and second magnet rings can be magnetized separately between the first and second magnet rings.

Abstract: A window regulator includes an electric motor having a drive shaft, a window slider, a transmission having an input driven by a drive shaft and an output driving the slider. A geared motor includes a drive shaft, a reduction gear coupled to the drive shaft and having a transmission ratio less than 1, and a piezoelectric element selectively locking the drive shaft. The window regulator can be used to prevent fraudulent opening of a window and to reduce the jamming force of an object between the window and the window frame.

Abstract: An actuating device, specifically to actuate locking differentials on vehicles, having an actuating shaft, a drive unit to drive the actuating shaft, where the drive unit comprises an armature core non-rotatably mounted on the actuating shaft and a commutator non-rotatably mounted on the actuating shaft, having an electromagnetic brake unit to brake and/or to hold the actuating shaft, where the brake unit includes a brake hub flange non-rotatably mounted on the armature, and having a single- or multi-piece housing tightly enclosing the drive unit and the brake unit, where the free end of the actuating shaft extends from the housing.

Abstract: Electromagnetic retarder brake systems, and methods for their use, are provided utilizing specified thickness conductive layers. The specified thickness of the conductive layer in each system is determined to obtain a certain desired torque at a certain desired low rotational frequency. The specified thickness conductive layer is disposed between a winding and a rotor within each system. By utilizing a specified thickness conductive layer, torque on the rotor at low rotational frequencies is increased, thereby improving deceleration capabilities.

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 disk drive is disclosed comprising a disk, a head actuated radially over the disk, and a spindle motor for rotating the disk. The spindle motor comprises a stator having at least one stator coil wrapped around a stator tooth. The spindle motor further comprises a hub rotated by the stator when current is applied to the stator coil, and a locking spring arm having a fixed base. The locking spring arm engages the hub when no current is applied to the stator coil, and the locking spring arm disengages from the hub when current applied to the stator coil generates a magnetic flux which pulls the locking spring arm away from the hub.

Abstract: The invention comprises a retarder system for use with road vehicles. The retarder system discloses an improved vehicular retarder which incorporates the use of a PMG Gear ratio which permits use of a permanent magnet generator on a secondary shaft that is coupled by the gear ratio to a drive train.

Abstract: The invention relates to an electromechanical wheel brake device, with an electric motor that can press a frictional brake lining against a brake body (brake disk) by a reduction gear (planetary gear) and a rotation/translation conversion gear (ball screw). The invention proposes embodying the electric motor as a transverse flux motor with three phase windings; each phrase winding has a circular, annular excitation winding that is disposed inside U-shaped yokes, which are distributed over the circumference of the excitation winding. This embodiment of the electric motor permits a compact design of the electric motor in an annular, hollow shaft design so that the reduction gear and the rotation/translation conversion gear can be disposed at least partially inside the electric motor.

Abstract: Small permanent magnets are affixed to the protruding portion of a rotor of a motor that is coupled to gears in a gear enclosure. The rod of a window covering is coupled to the gears such that when the motor is energized by a user command signal, the window covering moves. Small braking magnets are also affixed to the receptacle of the gear enclosure, such that when the motor is deenergized, the magnetic coupling between the magnets of the rotor and those of the gear enclosure brakes the rod from turning under the weight of the window covering.

Abstract: Brake assembly for cyclists' training device, provided with a support structure (7) on which there is rotatably mounted a shaft (10) having, keyed thereto, a roller (6) rotating in contact with the rear wheel of a bicycle. An end portion (12) of the shaft (10) is provided for this purpose with magnetic elements (13) able to exert a resistive torque and provided with a rotor (17) keyed onto the shaft (10) and carrying, fixed thereon, one or more permanent magnets (18) and a stator (19) mounted on the support structure (7) in the vicinity of the rotor (17). The stator (19) is composed of a disk of ferromagnetic material (20) and a shaped plate (21) of substantially conductive and non-magnetic material fixed to the ferromagnetic disk (20) on the side where the rotor (17) is located.

Abstract: A brake coupling combination for a motor, preferably an electric motor, consisting of a brake which can be attached to the motor, the brake having a flange (1) with which it is directly connected to a correspondingly shaped part of the motor, characterized in that the brake is mounted on the end of the shaft (9) of the motor by means of a hub (4) and that a flexible coupling (K) connects directly to the brake for connection to a second shaft.

Abstract: A safety locking device for electromechanical equipment provided with a rotating shaft, particularly an aircraft wheel brake with a safety locking device. The device comprises a first friction element connected rotationally to the shaft, and a second friction element immobile rotationally and extending opposite the first friction element. One of the two friction elements is able to move in translation, under the action of a controllable actuator, between a locking position and a release position. The locking and release positions correspond to successive angular positions of a selector able to move in rotation and connected in translation to the friction element able to move in translation. The selector is maintained in any one of its angular positions by a resilient member, while the actuator provides solely the passage of the selector from one angular position to the following one, and consequently passage from the locking position to the release position or vice-versa.

Abstract: The front brake of an electric motor has mechanical structure and is fitted on the output spindle at the front end of the electric motor, able to diminish the dimensions of an electric motor and save cost, and having no problem pertaining to circuit control and power compatibility in case of maintenance.

Abstract: An electric motor with an electromagnetic brake is disclosed, particularly for use in an angle grinder, which has a stator having at least one pole pair, in which at least one pole has a pole shoe which points to the inside towards the rotor periphery and is surrounded by a stator winding. The pole accommodates the brake means for braking of the rotor of the electric motor. The brake element can be adjusted against the braking force by the magnetic field of the stator winding when the motor is activated. The brake element is constructed of magnetically conductive material as a rocker which is exposed to the braking force off-center of the swivel axis of the brake element. As a result of the off-center application of force the brake element having a disengagement arm can be arranged in the magnetic flux of the stator winding such that a high disengagement moment can be achieved and rapid braking can occur at shutoff.

Abstract: A tube motor with an electric motor drive with a drive shaft located in a gear box. A reducing gear with a driven shaft is located in a gear box and coupled with the drive shaft via a gear input shaft for rotary securing of the driven shaft especially when the drive is disengaged. A wrap spring brake with a wrap spring works against the gear box, while the drive shaft and the gear input shaft work together with the wrap spring. Located between the wrap spring and the gear housing and secured against torsion is an annular element which diverts a moment introduced by the driven shaft into the gear housing.

Abstract: An automatically acting braking system for a stepper motor (10) of the type having a rotor (18) that is radially centered within a stationary stator (12) and which rotates about the central axis of a central shaft (30). The rotor (18) is allowed to axially slide back and forth, biased in one direction continually by a resilient means (40). When the stator (12) is energized, it pulls the rotor (18) to an axially centered position within stator (12), but when it is de energized, the resilient means (40) pushes the rotor (18) to one side, lockingly engaging its teeth (24) with the teeth (44) of a fixed locking ring (42).

Abstract: An automatically acting braking system for a stepper motor (10) of the type having a rotor (18) that is radially centered within a stationary stator (12) and which rotates about the central axis of a central shaft (30). The rotor (18) is allowed to axially slide back and forth, biased in one direction continually by a resilient means (40). When the stator (12) is energized, it pulls the rotor (18) to an axially centered position within stator (12), but when it is de energized, the resilient means (40) pushes the rotor (18) to one side, lockingly engaging its teeth (24) with the teeth (44) of a fixed locking ring (42).