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: A rotary device includes an output shaft securely connected to a sandwiched structure including a central magnetic permeable member and two outer magnetic un-permeable members. The sandwiched structure is enclosed by a ring composed of a plurality of sections assembled by the sandwiched structure. Each section has another sandwiched structure which is rotated by a cam member mounted on the output shaft by links. The output shaft is rotated by an initial force and will be rotated by the magnetic force by the inter-action between these sandwiched structures without extra force applied on the output shaft.

Abstract: A motor-synchronous exciting brake structure having a housing containing a stator and a rotor located at the center of the stator, the two ends of the housing being respectively mounted with an end cap, and the rotor shaft of the rotor being mounted with a brake structure which is used to brake the rotor, characterized in that the brake structure is provided with a floating element slidably located at the rotor shaft and the end face of the floating element, corresponding to the end cap, is provided with a plurality of brake blocks for braking purpose, and a triggering element is slidably mounted within the floating element, an elastic element is urged by the triggering element and the floating element, and further, the end face of the triggering element, corresponding to the rotor, is formed with two corresponding guiding slots, and one side of the guiding slot is provided with a sloping face, wherein the sloping face is inclined toward the end face, the other end of the floating element is a limiting plate

Abstract: An electromagnetic retarder apparatus with a built-in exciter having a retarder exciter inside thereof for generating braking torque by an eddy current produced in an eddy-current cylinder as a plurality of magnetic poles that are alternately magnetized to N and S poles by a field current caused to flow by a voltage generated in the exciter are caused to rotate in a relation to the eddy-current cylinder disposed at a location facing the magnetic poles; the eddy-current cylinder comprises a core formed by laminating a magnetic material, and short-circuiting method provided on the laminated core in the axial direction thereof for causing the generated eddy current to flow therein.

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 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 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: 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: An electromagnetic coupler couples a first rotating element with a second element with a torque transfer between the first and second elements. The coupling is solely by a magnetic field which can be fully coupled, fully uncoupled or modulated to provide a variable transmission of power between the first and second elements. The electromagnetic coupler comprises a set radially disposed electromagnets and a concentric set of pole pieces separated by an air gap. The magnetic field between the electromagnets and the pole pieces is increased as the current through the electromagnets is increased. At low current, there is substantial slippage between the respective driving and driven elements. With full magnetic coupling, the electromagnets and pole pieces are fully coupled or without any slippage therebetween. When the magnetic field is eliminated, there is no torque transfer between the driving and driven elements.

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: An electric machine with a stator and a rotor arranged in the drive train of a drive unit is disclosed. A vibration insulation device is incorporated in the rotor of the electric machine. The electric machine can function as a starter/generator, a generator vehicle brake, an auxiliary drive and/or an active vibration damper.

Abstract: A hysteresis slip clutch having an adjustable stall torque is provided. The clutch components include first and second rotors, with a housing at least partially enclosing the rotors. An annular permanent magnet is rigidly mounted on the first rotor and an annular hysteresis sleeve is rigidly mounted to the second rotor. The first and second rotors are mounted within the housing such that the magnet and hysteresis sleeve are concentrically located and axially aligned with one another within the housing. In this orientation, magnetic flux from the magnet penetrates the hysteresis sleeve and magnetic hysteresis developed within the hysteresis sleeve acts to oppose relative angular motion between the first and second rotors. The magnetic hysteresis establishes a torque by which angular motion of the first rotor is transferred to the second. A annular magnetic shunt is adjustably mounted to the housing.

Abstract: A paper-making machine or an off-line coater includes a rotatable drive unit and a rotatable driven element in the form of a roll, cylinder, pulley and/or gear. A clutch includes a rotatable input shaft coupled with the rotatable drive unit. At least one drive rotor is connected with the input shaft, and includes a plurality of magnetic coils. Each magnetic coil includes a coil winding. At least one driven rotor is positioned axially adjacent to at least one of the drive rotors. Each drive rotor includes a plurality of angularly spaced electrical conductors which are positioned adjacent to at least one of the drive rotors. A rotatable output shaft is coupled with the driven rotor and the rotatable driven element. A source of modulated direct current power is coupled with each of the magnetic coils, whereby a magnetic flux generated by the drive rotor and a coupling force between the drive rotor and the driven rotor can be varied.

Abstract: An electromagnetic clutch in which an annulus of sound dampening material is sandwiched between an armature disc and a hub assembly, particularly a web portion thereof. The annulus and web coact to define a constrained-layer damping system for reducing noise when the armature disc is snapped into engagement with the rotor of the clutch, slipping prior to lockup, while the armature is magnetically locked to the rotor, and also during slipping and disengagement of the armature disc. The design provides a reduced axial-length package relative to prior armature assemblies incorporating constrained-layer techniques.

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: A magnetic slip clutch system that can be used tin a number of different applications where a slip clutch is desired to be used; and particularly, to applications where the clutch is desired to be fully disengaged, i.e., free-wheeling, fully engaged to transmit 100% of the power, or coupled in a modulated or slip manner for transmission of a variable amount of power. The torque transfer is modulated by controlling the electric power to the clutch.

Abstract: A vehicle control device is provided that is capable of functioning as a transmission synchronizer, an electromagnetic clutch, a starter for an engine, and a generator. The device includes a first member having a plurality of inwardly extending poles and a plurality of coils that are wound upon the poles. The first member is connected to an engine output shaft for rotation therewith. The device also includes a second member that is disposed within the first member. The second member is connected to a transmission input shaft for rotation therewith. Finally, the device includes means for energizing the coils of the first member to control the operation of the control device. By controlling the energization of the coils and the relative motion of the first and second members, the control device can be used as a transmission synchronizer, a clutch, a starter for the vehicle's engine, and a generator for the vehicle's battery.

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: An adjustable coupler has a group of magnet rotors with permanent magnets separated by air gaps from non-ferrous conductor elements presented by 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 control the load speed under varying load conditions.

Abstract: An electromagnetic clutch includes a field member having a hollow in a center thereof and carrying a field coil in the form of a ring, a shaft rotatably placed in the hollow of the field member, a rotor member fixedly attached on the shaft, the rotor member being arranged on one side of the field member, a driving member rotatably mounted on the shaft, the driving member being arranged on one side of the rotor member, and an armature member attached to the driving member, the armature member being arranged between the rotor member and the driving member and bendable toward the rotor member.

Abstract: A motor, encoder/resolver, and/or dynamic brake assembly in which the dynamic brake, when part of the assembly, is mounted on a rear cover plate of a modular housing for the auxiliary components. When a resolver or encoder is part of the assembly, the motor shaft extends only a short distance beyond the resolver/encoder housing module; far enough to be engaged by the armature of the dynamic brake if the brake is part of the assembly. In an assembly that does not use a dynamic brake, the same rear cover plate is used to close the encoder/resolver housing module.

Abstract: The invention relates to an electric motor having a locking device and a brake actuator for an electric system which includes such an electric motor. The locking brake has a simple configuration and includes a conical ring which is mounted so as to be axially displaceable on the motor shaft of the electric motor of the brake actuator. In a first axial position, the conical ring (26) permits a rotation of the motor shaft (12) in both directions and, in a second axial position, the conical ring is in engagement with the motor shaft (12) and rotates with the latter. In the second axial position of the conical ring (26), a rotation of the motor shaft (12) in one rotational direction leads to the situation that the conical ring (26) is in engagement with the lock ring (24) of the brake actuator (2). The lock ring (24) is fixed so that it cannot rotate relative to the motor shaft (12).

Abstract: A new and improved fan clutch system for use with an internal combustion engine which provides variable speed drive of the fan by the engine with the coupling between the fan and the engine being solely by a magnetic field. The variable speed drive provides true proportional control of the convective heat transfer from the radiator.

Abstract: A position of a second permanent magnet with respect to a first permanent magnet is defined by assembling a driving side support member, a thrust bearing, a spacing member, a radial bearing, and a driven side support member. The first and second permanent magnets are respectively held on the driving side support member and the driven side support member. Accordingly, variation of a magnetic gap between the first and second permanent magnets can be reduced. Variations in assembling the parts hardly affect the variation of the magnetic gap.

Abstract: A power output apparatus (20) of the present invention includes a clutch motor (30), an assist motor (40), and a controller (80) for controlling the clutch motor (30) and the assist motor (40). The clutch motor (30) includes an outer rotor (32) linked with a crankshaft (56) of a gasoline engine (50) and an inner rotor (34) connecting with a drive shaft (22). The assist motor (40) includes a rotor (42) connecting with the drive shaft (22). A control CPU (90) of the controller (80) controls a first driving circuit (91) to enable the clutch motor (30) to carry out the regenerative operation. The clutch motor (30) accordingly regenerates energy corresponding to a slip between the outer rotor (32) and the inner rotor (34) as electric power.

Abstract: A variable speed eddy current drive has a driven member and an output member. The driven member is structured and arranged to be coupled to a motor shaft. The output member is structured and arranged to be coupled to a load. The drive also has an armature and an electromagnet. The armature is coupled to either the driven member or the output member, while the electromagnet is coupled to the other of the driven member or the output member. The drive is provided with a coupler that is in addition to the armature and the electromagnet. The coupler is selectively operable between a coupled position and an uncoupled position. Actuating the coupler to the coupled position causes the output member to rotate at the same speed as the driven member, with no slip between the two members. The coupler can be actuated between the coupled and uncoupled positions while the drive is rotating. The coupler can be actuated to move either axially or radially.

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 controllable brake (20) including a rotor (28) supported by a shaft (30) which is rotatably supported by bushings (42) received in housing (22). A coil assembly (48) creates a magnetic field within a pole piece (32), which is preferably manufactured from a powdered metal material, which preferably has a density of between about 6.8 and 7.0 gm/cm. A magnetically-soft medium is contained within first and second gaps (86, 88) located between pole piece (32) and rotor (28). In one aspect, a magnetic saturation zone (25) reduces the propensity of magnetizing the shaft (30). In another, the pole halves (24, 26) are received in radially-spaced pole pockets (37) formed in the housing (22) and include an axial bias spring (70) to ensure intimate contact. In another aspect, a lip projection (76) traps fluid (23) between the lip projection (76) and shaft (30) and minimizes fluid exposure to the shaft seal (44). In another aspect, cooling fins (55) or a projection (53) restrains rotation of the housing (22).

Abstract: Although a rotor shaft of a spindle motor for driving an optical disc is constituted by stainless steel not to cause damage or friction when the disc is mounted or removed, it is intended to provide a spindle motor which does not require to use a material with bad workability such as stainless steel. A rotor shaft or a rotor cap mounted on the rotor shaft is made from a resin material or an alloy material with good workability such as brass, and a hard coating is provided on its surface to provide hardness necessary for components made of a material with good workability.

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: An electric drive for small vehicles, especially wheelchairs, includes a d.c. motor, which is arranged as a wheelhub motor in the running wheel of the small vehicle. Efficiency and manufacturing costs are improved, while ensuring simple assembly, wherein the possibility of automatically locking the running wheels is provided, along with a short and lightweight design. The d.c. motor is an external rotor motor, whose external rotor forms the wheelhub or the wheel rim of the running wheel. The stator of the d.c. motor is stationarily connected to the small vehicle via a brake housing (3). A central spring pressure brake is provided which can be released electromagnetically and manually and brakes the external rotor of the d.c. motor in the case of a power failure.

Abstract: A geared electric motor 1 used for power window apparatuses, for example, which is provided with an mature 7 having an armature shaft 7a, an output shaft 8 connected with the armature shaft 7a through a worm gear pair (7a7 and 17) and two friction plates 9 and 10 to be in contact with both end faces of the armature shaft 7a. The armature shaft 7a of this motor 1 is prevented from rotation by frictional resistance generating between the friction plates 9, 10 and the armature shaft 7a even if the output shaft 8 is applied with rotatory force.

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: The present invention is intended to provide a one-way clutch capable of preventing the inner circumferential surface of the outer ring of the one-way clutch from being deformed even when the outer ring of the one-way clutch for a stator constituting a torque converter is integrally formed with the stator made of plastic.

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 adjustable coupler has a rotary magnet rotor with magnet modules gaps from electroconductive elements on an electroconductive rotor. The magnet modules each have two side-by-side permanent magnets with their respective poles reversed and have a neutral plane between the magnets. The magnet modules can be turned for torque adjustment between a maximum torque position in which the neutral planes intersect at the rotary axis of the coupler, and a minimum torque position at which the magnet modules are turned 90 degrees from the maximum torque position.

Abstract: A magnetic coupling includes a cylindrical housing, a spindle, an adjusting plate, two pairs of permanent magnet discs, two hysteresis material discs, and a screw member. The spindle is rotatably supported at its axial position by the housing. The adjusting plate is rotatably supported by the spindle to partition an interior of the housing into two sections in a direction of the spindle. The two pairs of permanent magnets are provided in the two corresponding sections to respectively oppose each other. One of each pair of permanent magnet discs is fixed in the housing and the other thereof is fixed to the adjusting plate. Each permanent magnet disc has magnetic poles with polarities that alternate in a circumferential direction. The hysteresis material discs are fixed to the spindle and arranged between the corresponding pairs of permanent magnet discs at a predetermined gap. The screw member fixes the adjusting plate to the housing.

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 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.

Abstract: A magnetic coupling device has an electroconductive rotor presenting a band of electroconductive material and has a magnet rotor with permanent magnets which are 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. The electroconductive rotor preferably has two such bands positioned on opposite sides of the magnet rotor. The rotors may have sheaves mounted thereon.

Abstract: A drive arrangement for a hybrid vehicle with an electric motor, which has a rotor with a hub body and a stator, and with two engagable and disengagable dry-disk clutches. Each of the dry-disk clutches has a first functional component as well as a second functional component. The second functional component is frictionally connectable to the first functional component in order to provide a torque transmitting connection.

Abstract: An electromagnetic clutch for a compressor in an air conditioning apparatus for an automobile. A temperature fuse unit 13 is arranged in an electric circuit for an electromagnetic coil of the clutch for opening the circuit when a temperature increase is generated due to an occurrence of seizing. The temperature fuse unit 13 is arranged in a coil housing 4 at a location adjacent a frictional surface 2a of a rotor of the clutch and an inner sleeve portion 4a of the coil housing 4. During normal operation of the clutch, heat around the electromagnetic coil is transmitted to the coil housing of an increased heat conductivity, made of a magnetizing metal materials, thereby preventing the temperature around the temperature fuse 13 from being increased.

Abstract: Irregularities on the face of the pulley groove of the pulley for driving the rotor shaft of the generator through the one-way clutch are positively extended and a frictional force between the face and the belt is increased, so that a higher torque than the drag torque can be transmitted to the one-way clutch without causing a slippage of the belt. Since no slippage occurs on the belt, the belt life can be extended. Since the one way clutch is positively operated, the inertial energy of the rotor can be effectively recovered.

Abstract: A magnetic coupler has a magnetic disc containing permanent magnets located between two electroconductive plates and separated therefrom by air gaps. The magnetic disc and electroconductive plates are mounted on coaxial or parallel-spaced input and output shafts so that rotation of the input shaft causes rotation of the output shaft by way of magnetic friction between the permanent magnets and the electroconductive plates.

Abstract: An improved startup device for the rotor of a permanent-magnet synchronous motor, particularly adapted for liquid conveyance pumps, such as those used in electrical household appliances or the like, which are equipped with a permanent-magnet synchronous motor of the type comprising a stator unit with a pack of metal laminations and electrical windings supported by a body that forms a substantially cylindrical chamber that accommodates, upon assembly, the rotor unit, which is axially crossed by a motor shaft.

Abstract: A gear motor (1), with an electric motor (4) whose rotor (7) has a hollow shaft (8), drives, through at least one gear box (26) with at least one drive step, at least one load. For the purpose of compact configuration combined with low vibration, there is coaxially disposed in the hollow shaft (8) an output shaft (19) which can be shifted selectively by means of a first clutch (24) to the hollow shaft (8), and by means of a second clutch (16) via the gear box (26) to the hollow shaft (8). Preferably the clutches are configured as magnetic clutches, and again preferably the first clutch (24) is disposed for the direct shifting of the hollow shaft (8) to the output shaft (19) at the one end of the hollow shaft (8), and the second clutch (16) at the other end of the hollow shaft (8). The gear motor (1) is used preferentially for driving rotary parts in crystal pulling apparatus.

Abstract: Device for positioning a rotating body movable about an axis in relation to a stator body including a magnetic bearing and a locking/releasing device. The locking/releasing device embodies a plurality of clamps with pads adapted to radially grip a shaft of the rotating body. The clamps are articulated on the stator body about axial pins spaced from the rotational axis and evenly distributed in an angular manner about the rotational axis, and can be pivotally moved about the axis, by a moving control part between a released configuration in which the gripping pads are at a maximum distance from the axis and a locked configuration in which the pads are at a minimum distance from the axis suitable for inducing radial clamping of the shaft.

Abstract: A driving assembly for motor wheels including a plurality of permanent magnets arranged around the outer periphery of a securing element on an axle for forming a stator. When electric currents are passed through a plurality of winding coils in an inner wheel frame, an induction electromagetic field is generated to drive the inner wheel frame in the outer wheel frame to rotate. The inner wheel frame has a clutch ring for transmitting the power of the inner wheel frame to a driving gear of a reduction mechanism to drive the outer wheel frame. A clutch element is disposed between the clutch ring and the driving gear, the clutch element being capable of axial movement along the axis of said axle for controlling power transmission.

Abstract: A magnetic hysteresis clutch comprises an external rotor and a rotary magnetic inductor arranged in said external rotor so as to define a radial air gap. Rings of ferromagnetic hysteresis material are mounted in said external rotor so as to be able to undergo a reversible thermal expansion of their internal diameter leading to an increase in the radial air gap. The clutch is designed so that the heating up of the ferromagnetic material in the rings which accompanies an increase of the slip between the external rotor and the rotary magnetic inductor, produces a reversible increase in the radial air gap which is sufficient to decrease the transmitted torque. Thus it is possible to provide a magnetic hysteresis clutch in which the transmitted torque reversibly decreases when the slip increases.

Abstract: A pump driven by an electric motor includes a stator, a rotor cooperating with the stator, a rotating drive-shaft associated to the rotor, a hermetically sealed chamber, and a disk wheel within the sealed chamber and joined to the drive-shaft. The sealed chamber is sealed by a first ring gasket around the drive-shaft and in the sealed chamber and a second ring gasket fixed to the drive-shaft and against the first ring gasket. The first and second ring gaskets are pressure coupled to each other. At start-up of the motor, the rotor or the stator is allowed to turn freely for a certain initial arc without torque being applied to the coupling so that inertia can be accumulated to overcome resistance of the coupling when the torque is subsequently applied to the coupling.