Abstract: A power supply connector has a first part and a second part that are connected to each other such that they can turn relative each other within a predefined and/or restricted turning angle. The first part includes a first set of plurality of conductors and the second part includes a corresponding second set of plurality of conductors, wherein the pairs of conductors are electrically connected by electrical connections including a connection tip on one of the first and the second part and a contact surface on the other one, wherein the electrical connections are provided in at least one circular shape around a turn axis of the power supply connector The turning angle between the first part and the second part is limited to the shortest angular extension of the contact surfaces and the contact surfaces are distributed such that the pair of conductors are permanently electrically connected.

Abstract: A rotary joint includes a first part and a second part configured to rotate around a rotation axis against the first part. The first part has a first magnetic core, a sliding brush, and a capacitive data link component. The second part has a second magnetic core for coupling power with the first magnetic core, a sliding track for galvanic coupling with the sliding brush, and a second capacitive data link component to transfer data from and/or to the first capacitive data link component. To weaken magnetic stray fields from the magnetic core, the rotary joint is a disc-type rotary joint, and the sliding track is arranged radially between the second magnetic core and the second capacitive data link component.

Abstract: Embodiments disclosed herein describe methods for an improved electrical connector system.

Abstract: A slip ring body for electrically contacting an asynchronous machine includes first and second slip rings rigidly connected to one another, with at least two conductor bars fastened to each of the slip rings. At least one of the slip rings has a recess for passage of the conductor bars of the other slip ring and defining around the recess a first region in which air is at least partially present and which has a magnetic conductivity that is lower than a magnetic conductivity in a second region in which the conductor bars to the one slip ring are fastened, or which second region is embodied for contacting with an energy-transmitting brush. The first and second regions are not made of copper. The recess defines an opening cross-sectional area which is greater than a cross-sectional area of the conductor bars fastened to the one slip ring.

Abstract: A generator with reduced reverse torque which may be used as a singular, point of use, compact electric generator that produces power with high efficiency and very low reverse torque. The generator comprising a stator having slots and stator coils and a series of slot rotors placed in relation to the stator coils such that minimal destructive interaction is caused between magnetic fields of each rotor and induced magnetic fields of the stator when the power generator is connected to an electric load with at least a portion of that power being sent to a storage device where a portion of the stored power is provided to excitation circuitry utilized to re-excite a motor to drive the slot rotors.

Abstract: A discharging device for discharging electrical interference, in particular currents, from a rotor part of a machine, said rotor part in particular being a shaft, into a stator part (17) of the machine, the discharging device having a contact device (11) comprising a contact element (13) which is accommodated in an axially displaceable manner in a guide and which is acted on by a contact force device (15) for generating a shaft contact force (FW) in order to establish electrical contact between a shaft contact surface (19) of the contact element (13) and a rotor contact surface (20) of the shaft (18), wherein the guide has a stator contact surface (25) for forming an electrical connection with the stator part (17) and the discharging device has a guide contact force device (21) for generating a guide contact force (FF) between a guide contact surface (24) of the contact element (13) and the stator contact surface (25) electrically connected to the stator part (17).

Abstract: A slip ring transmitter for electrically connecting assemblies of rotary-table machines is described and comprises a slip ring with a signal unit for transmitting signals and/or data and with a power unit for transmitting electrical power. As the signal unit is formed such that it is modularly detachable can in particular be axially drawn off from the power unit, the signal unit can be inspected and/or replaced separately from the power unit. This improves the reliability of the transmission of signals and/or data and enables individual optimization of the power unit.

Abstract: The subject invention provides a lighting system with a light source, a plurality of spokes to house the light source and a structural hub adapted to connect to the plurality of spokes. A method of using the lighting system includes connecting the plurality of spokes to the hub, emitting light from the light source housed within the plurality of spokes and connecting the hub to an electrical connection housing.

Abstract: A wire brush for a slipring includes a contact section, from which a stabilizer arm is extending backwards towards the brush block of the slipring. The stabilizer arm holds a friction section, which is in friction contact with the contact section at a friction contact area. Such contact, in operation, generates internal friction within the brush when the brush is moved and, therefore, suppresses oscillations of the brush.

Abstract: The invention relates to a detection device for detecting mechanical functional states of a motor vehicle lock, in which at least two binary signal outputs are provided which define a logical state of the detection device through the respective electrical potentials present there. It is proposed that the functional state of the motor vehicle lock is determined on the basis of the logical state of the signal outputs and of the electrical resistance between the predetermined signal outputs.

Abstract: A horizontal multi-joint robot includes: a first joint capable of swiveling around a first axis; a second joint capable of swiveling around a second axis that is parallel to and spaced apart from the first axis; and a duct connected between the first joint and the second joint. The first joint has a first connecting portion forming a predetermined angle relative to the first axis. The second joint has a second connecting portion forming a predetermined angle relative to the second axis. The duct has a first end and a second end. The first end is connected to the first connecting portion. The second end is connected to the second connecting portion.

Abstract: A rotary electric machine includes a rotating shaft 18 rotatably supported by a housing, a stator including armature windings, a rotor including field cores and field windings, slip rings electrically connected to the field windings, brushes contacted and electrically connected to the slip rings, and a brush holder including the brushes and terminals. The rotor is provided with one or more fans. The terminals include exposed portions exposed at least partially from the brush holder, and the exposed portion are disposed on a ventilation path of a cooling airflow W generated by rotation of the fans. Accordingly, since the exposed portion are disposed on the ventilation path of the cooling airflow, heat caused by an energization can be efficiently dissipated, and heat generated in the brushes due to the interfacial friction is dissipated from the exposed portions.

Abstract: Provided are: an impact fastening tool which prevents a torque detector from missing a signal and extends service life by adopting a fixed connector that prevents the trouble of being instantaneously separated (bounced) from a rotating electrode by intermittent impacts and has a shape allowing the progression of friction to be delayed structurally; and a torque tester. Both end portions of the fixed connector are fixed, and at least two protrusion portions are formed between the both end portions. The rotating electrode is disposed between one protrusion portion and the other protrusion portion such that the rotating electrode contacts the fixed connector at two or more points or in a line form. A signal required for the torque detecting means is transmitted through the contact between the rotating electrode and the fixed connector.

Abstract: A slip ring device includes an insulating molded body in which a pair of slip rings and a pair of connecting conductors are provided. The insulating molded body includes a molded body main body portion disposed in a position further from a rotor main body than a bearing provided on a shaft, the slip rings being provided in the molded body main body portion, an opposing portion disposed between the bearing and the rotor main body, and a pair of beam portions that connect the molded body main body portion to the opposing portion, the connecting conductors being provided respectively in the beam portions. A pair of shaft grooves respectively accommodating the pair of beam portions are provided in the shaft. A spreading suppression portion for preventing resin with which a field coil is impregnated from spreading into the shaft grooves is provided in the opposing portion.

Abstract: In a rotary electric machine, a first pole core body and a second pole core body are produced using solid cores, and first slits are formed on outer circumferential surfaces of a first boss portion and a second boss portion at a uniform pitch in a circumferential direction so as to have groove directions oriented in an axial direction to disrupt pathways of eddy currents that flow on the outer circumferential surfaces of the first boss portion and the second boss portion.

Abstract: The disclosed invention is a slip ring assembly that provides electrical power transfer to centrifugal turbomachinery while minimizing or eliminating the presence of wires in the flow path. The device transfers electrical power through a set of wires connected to a plurality of brushes that are held rotationally stationary, but allowed to displace axially or radially through a set of springs. The brushes make contact with conductive busbar rings, transferring electricity to the busbar rings. The busbar rings rotate with the centrifugal turbomachine with a set of wires that connect the busbar rings to the blades or other aerodynamic surfaces of the centrifugal turbomachine.

Abstract: The disclosed invention is a slip ring assembly that provides electrical power transfer to centrifugal turbomachinery while minimizing or eliminating the presence of wires in the flow path. The device transfers electrical power through a set of wires connected to a plurality of brushes that are held rotationally stationary, but allowed to displace axially or radially through a set of springs. The brushes make contact with conductive busbar rings, transferring electricity to the busbar rings. The busbar rings rotate with the centrifugal turbomachine with a set of wires that connect the busbar rings to the blades or other aerodynamic surfaces of the centrifugal turbomachine.

Abstract: A method of securing a fan member to a rotor assembly of an electric machine. The method includes positioning the fan member adjacent the rotor, aligning at least two mounting members extending radially outwardly of the central hub of the rotor assembly with a corresponding at least two mounting elements extending radially inwardly of a hub portion of the fan member, and securing the at least two mounting members to the corresponding at least two mounting elements.

Abstract: An electric motor with contact commutation may include an external stator and an internal, rotatably mounted rotor. A magnet arrangement including at least one permanent magnet may be arranged fixedly on the rotor. A coil arrangement including at least one electric coil may be arranged fixedly on the stator. A contact commutation assembly may be in communication with the coil arrangement.

Abstract: A radio frequency rotary coupler with its power dividers/couplers separated among multiple circuit layers that are axially stacked and interconnected using coaxial feeds. This architecture allows for multiple layers of circuits with minimal outside diameter and while minimizing increase in axial length. The coupler includes a stator, rotor, and dynamic capacitive ring. The stator includes at least a first stator circuit layer with a primary stator power divider (SPD), a second stator circuit layer with at least one secondary SPD, and stator coaxial feeds coupling the primary SPD and the secondary SPD(s). The rotor includes a first rotor circuit layer with a primary rotor power divider (RPD), a second rotor circuit layer with at least one secondary RPD, and rotor coaxial feeds coupling the primary RPD and the secondary RPD(s). The dynamic capacitive ring couples the stator and the rotor via the secondary SPD(s) and RPD(s).

Abstract: The disclosed invention is a slip ring assembly that provides electrical power transfer to centrifugal turbomachinery while minimizing or eliminating the presence of wires in the flow path. The device transfers electrical power through a set of wires connected to a plurality of brushes that are held rotationally stationary, but allowed to displace axially or radially through a set of springs. The brushes make contact with conductive busbar rings, transferring electricity to the busbar rings. The busbar rings rotate with the centrifugal turbomachine with a set of wires that connect the busbar rings to the blades or other aerodynamic surfaces of the centrifugal turbomachine.

Abstract: The lifetime of sliding contact surface(s) of a precious metal or a precious metal alloy can be enhanced by embedding at least one nano-particle in the layer forming the sliding contact surface(s).

Abstract: An apparatus is adapted to be in electro-mechanically communication with a vehicle and configured to record information related to crash investigation and early warning. The device records and stores information as well as analyzes it to provide an occupant of the vehicle early warning as to potential hazards that arise.

Abstract: A restricting member is provided that is in contact with respective bent lead portions of a long-sized lead and a short-sized lead and imparts a tension to linear lead portions thereof in a mold for insert molding. The restricting member reliably prevents the leads from displacement and deformation resulting from the pressure of the resin at the time of insert molding, and allows the long-sized lead and the short-sized lead to be disposed at proper positions in a molded body.

Abstract: A slip ring arrangement comprises a brush with a first contact material on the surface, which rests on a slideway with a second contact material on the surface. The slideway further comprises a layer with a third contact material beneath the second contact material. In this case, the abrasion of the brush is lower than that of the second contact material in the case of a sliding contact between the brush and the second contact material. In the case of a sliding contact between the brush and third contact material, the abrasion of the brush is higher than that of third contact material. As a result, the second contact material of the slideway is degraded first, which corresponds to the normal service life of a slideway. Subsequently, the brush is worn off relative to the third contact material, by means of which a further considerable extension in the service life is achieved.

Abstract: A medical apparatus (600) including: a magnetic resonance imaging system (602), a medical device (634), and a slip ring assembly (400, 500) for supplying electrical power to the medical device. The slip ring assembly includes: a cylindrical body (100), a rotating member (402) for rotating the medical device, a first cylindrical conductor attached to the cylindrical body, a second cylindrical conductor (108), a first set of conductive elements (112, 712) connected to the second cylindrical conductor; and a brush assembly (406) comprising a first brush (302) and a second brush (304). The first brush is operable to contact the first cylindrical conductor. The second brush is operable to contact the set of conductive elements. The first and second cylindrical conductive elements overlap at least partially. The second cylindrical conductor is connected to the cylindrical body. The first cylindrical conductor and the second cylindrical conductors are electrically isolated.

Abstract: A rotary electric machine including a brush used to supply a field current to a field winding of a rotor, a brush holder holding the brush, a power circuit portion connected to a heat sink having fins, and a case covering the power circuit portion and the brush holder. An air passage is provided between the brush holder and the fins of the heat sink, and an opening is provided to the case so as to cover component members of the brush holder in a shape conforming to an outer peripheral portion of the brush holder, from which cooling air is allowed to pass through the air passage.

Abstract: A voltage regulator device provided in a bearing of a rotary electric machine of a motor vehicle. The regulator device comprises a support and at least one electronic component configured to participate in the control of the electric machine. The support comprises a first part on which the at least one electronic component is mounted. The first part having an edge equipped with a brush holder provided with at least one brush-holder receptacle configured to accommodate a brush for making an electrical connection with a rotor of the electric machine. The device is configured to allow air to flow through the first part of the support, in contact with the brush holder. The device includes at least one air circulation slot provided through the support between the first part and the brush-holder. The support covers an air opening in the bearing.

Abstract: A brush holder assembly for an alternator having a rotational axis includes a pair of brushes each having a contacting surface defining a width and a height, and each having a shunt wire extending laterally from the brush in the widthwise direction. The brush holder assembly includes a housing having first and second brush chambers, corresponding first and second wire cavities each defining a cavity height, and first and second slots respectively interposed between the corresponding chamber and cavity. The respective shunt wires extend through the first and second slots then through the first and second wire cavities. The cavity heights are each at least approximately 0.9 times the height of one of the brushes. The height of the first wire cavity is less than approximately 0.97 times ((A/2) plus B), wherein A is the brush height and B is the distance between the brushes.

Abstract: A slip ring apparatus including a ring assembly having a conductive ring with a conductive ring engagement surface, a contact assembly having a contact element with a contact element engagement surface for engaging with the conductive ring engagement surface, and a surface discontinuity provided in at least one of the conductive ring engagement surface and the contact element engagement surface. An apparatus including the slip ring apparatus, wherein the apparatus includes a housing having an interior and a shaft rotatably extending through the interior of the housing. A method for reducing the potential of a hydroplaning effect in a slip ring apparatus, including providing a surface discontinuity in at least one of a conductive ring engagement surface and a contact element engagement surface.

Abstract: An electrical swivel system may have a movable swivel member adapted to connect to a landing gear and a fixed swivel member adapted to connect to an airframe. Each may have an interface apparatus whereby electrical signals may be conducted between components of the movable swivel member and the fixed swivel member. In this manner, electrical signals may be conveyed across a mechanically movable joint.

Abstract: A slip ring assembly includes a pair of conductive rings consecutively positioned along a center shaft of the slip ring assembly. The pair of conductive rings are electronically coupled to a high frequency signal source via a first twisted wire pair. The pair of conductive rings are electronically coupled to a data processor via a second twisted wire pair. The first and second twisted wire pairs have constant target impedances that are substantially similar. The first and second conductive rings are axially spaced at an axial distance that is sized so as to maintain the constant target impedance across the first and second conductive rings during transmission of a high frequency signal from the high frequency signal source to the data processor. The slip ring assembly provides a method for impedance matching across the conductive rings of the slip ring assembly.

Abstract: A lightning protection system is provided for a wind turbine. The wind turbine has an electrically grounded structure part, a main shaft electrically and mechanically connected to the grounded structure part, a blade hub rotationally connected via a main bearing to the main shaft and blades connected to the blade hub. The lightning protection system includes a down-conductor attachable inside one of the blades and a high voltage conductor for guiding lightning current, wherein a first end of the high voltage conductor is in electrical communication with the down-conductor. The lightning protection system also includes a high voltage contact attachable inside the main shaft, wherein a second end of the high voltage conductor is in electrical communication with the high voltage contact. Lightning current is guided from the down-conductor via the high voltage conductor to the high voltage contact.

Abstract: A rotary device for providing continuous electrical connections between dynamic, rotationally engaged connector components. The rotary device includes a rotor assembly comprising a plurality of slip ring elements electrically connected to a connector or cable at the rotor end of the device. The rotary device also includes a stator assembly configured to receive the rotor assembly, with slide contacts electrically connected to a connector or cable at the stator end of the device. The rotor assembly is rotationally coupled to the stator assembly, and the slip rings and slide contacts maintain electrical contact during rotation of the rotor assembly relative to the stator assembly. A first electronic device and a second electronic device connected using the rotary device can be freely rotated without twisting of the cable between the two devices. A method for assembling a rotary device configured based on the devices to be connected.

Abstract: Electrical machine, in particular AC generator, having a stator (16) and a rotor (20), wherein the rotor (20) has a conductor arrangement for exciting an electromagnetic field, having a device for transmitting electrical energy to the conductor arrangement, wherein the device for transmitting electrical energy comprises at least one sliding contact and at least one mating contact (66) which is fixed to the rotor, having a fitting sleeve (63) in which a roller bearing (28) for supporting a shaft (27) is preferably arranged, said shaft for the most part encasing the at least one mating contact (66) which is fixed to the rotor, wherein a fan (70) is arranged in the fitting sleeve (63).

Abstract: What is presented is a method of manufacturing a rotatable electric coupling. The rotatable electric coupling comprises a male connector half and a female connector half. The male connector half comprises one or more male coupling parts, one or more male insulator elements, and a male connector core that has a central burrow. The female connector half comprises a female core base having a channel, one or more female coupling parts that have a channel extender, one or more female core spacers that also have a channel extender, and a female end cap. The method comprises assembling the male connector half, assembling the female connector half, and inserting the male connector half into the female connector half.

Abstract: The invention concerns a method of reconditioning a slip ring transmitter of the gold wire type which has a slip ring, in particular a gold ring, for use with a gold wire board as the circuit board, including the steps: removing a gold wire board from the slip ring transmitter, and fitting a multi-brush board as a replacement for the gold wire board.

Abstract: In a rotor of the present invention, an interference is set to have a relationship so that an inner diameter of a press-fit projecting portion before press-fitting is smaller than a diameter of a shaft, and in the inner wall surface, a non-projecting portion is formed without projecting portions on a portion in which a weld line is generated by the molding.

Abstract: A slip-ring arrangement of a rotating electrical machine includes a plurality of slip-rings disposed concentrically about an axis of the electrical machine one behind the other in an axial direction, the plurality of slip-rings configured to be self-supporting.

Abstract: The invention proceeds from a rotating electric machine, in particular a double-fed induction machine in the power range between 20 MVA and 500 MVA, which comprises a rotor that rotates about a machine axis, is concentrically surrounded by a stator, and has a rotor plate body and a shaft, which rotor plate body bears a rotor winding that is arranged further outwards and is connected by means of connectors to slip rings that are arranged further inwards at the end of the shaft. A flexible and secure connection is achieved in that the connectors have mechanical connectors that run at right angles to the shaft to absorb forces arising owing to centrifugal acceleration, which mechanical connectors are connected on one side to a rotor winding head of the rotor winding and are supported on the other side on an auxiliary rim on the rotor plate body.

Abstract: A sliding contact assembly comprises: at least one contact slide track; a brush holder for holding at least one brush contact member and maintaining the at least one brush contact member in sliding contact with the at least one contact slide track during relative movement between the brush contact member and the contact slide track; and a collecting container disposed to collect particles of abraded material from the at least one brush contact member; wherein a cover is provided to surround substantially the brush holder and the at least one brush contact member, the cover having walls extending along a direction of the contact slide track laterally of the brush holder and the brush contact member and along a side of the brush holder remote from the contact slide track; the collecting container is disposed at a downstream end of the cover; and the cover is designed to channel a stream of air, generated within the cover by movement of the contact slide track, towards the collecting container.

Abstract: A system includes a generator. The generator is equipped with a plurality of field coils. A first collector ring is configured to be coupled to an excitation source. A first main lead is configured to direct a current through the plurality of field coils. The first main lead has first and second ends. The first end includes a first gooseneck axially coupled to the plurality of field coils. The second end is configured to axially couple to a first radial terminal of the generator.

Abstract: A dynamo-electric machine is provided comprising a stator and a rotor assembly which is rotatably mounted relative to the stator and which has a rotor shaft. The rotor assembly also has a rotor winding through which current flows and which is connected to terminals associated with the stator in an electrically conductive manner without interruption via a slip ring arrangement. The slip ring arrangement comprises at least two pairs of slip rings, each pair having a stator slip ring and a rotor slip ring that permanently rest against each other in a ring-shaped non-cylindrical contact zone. The two rotor slip rings are arranged between the two stator slip rings. Furthermore, each rotor slip ring is arranged on a rotor support disk that is rotationally fixed to the rotor shaft. The position of the two stator slip rings can be changed relative to each other in the axial direction.

Abstract: The current diverter rings (CDRs), captured CDRs, bearing isolators, and explosion-proof CDRs serve to dissipate an electrical charge from a rotating piece of equipment to ground, such as from a motor shaft to a motor housing. One embodiment of the explosion-proof CDR includes a stator that may be mounted to the equipment housing and a rotor that may be mounted to a shaft. The rotor may rotate with the shaft may be encompassed by stator and a cap, which cap may be secured directly to the stator or the housing. A conductive assembly may be positioned in a radial channel formed in the stator such that the conductive assembly contacts the shaft to conduct electricity from the shaft to the housing. Another embodiment of an explosion-proof CDR does not require a rotor. The explosion-proof CDR may be configured to define a flame path to achieve various explosion-proof certifications.

Abstract: Systems, methods, and apparatus associated for lifting brushes and shorting slip rings are provided. One embodiment may include a shaft in operable communication with a WRIM rotor; multiple slip rings positioned radially around the shaft and in electrical communication with rotor windings of the WRIM; multiple brushes adapted for selective contact with a respective one of the plurality of slip rings. In addition, the system may include multiple selectively activating electrical contacts in electrical communication with respective terminals of the rotor windings of the WRIM; and an actuating mechanism in operable communication with the brushes and the electrical contacts. When the actuating mechanism is actuated, the electrical contacts create electrical shorts between the slip rings and the rotor windings of the WRIM and the plurality of brushes are lifted from contacting the plurality of slip rings.

Abstract: A medical apparatus (600) including: a magnetic resonance imaging system (602), a medical device (634), and a slip ring assembly (400, 500) for supplying electrical power to the medical device. The slip ring assembly includes: a cylindrical body (100), a rotating member (402) for rotating the medical device, a first cylindrical conductor attached to the cylindrical body, a second cylindrical conductor (108), a first set of conductive elements (112, 712) connected to the second cylindrical conductor; and a brush assembly (406) comprising a first brush (302) and a second brush (304). The first brush is operable to contact the first cylindrical conductor. The second brush is operable to contact the set of conductive elements. The first and second cylindrical conductive elements overlap at least partially. The second cylindrical conductor is connected to the cylindrical body. The first cylindrical conductor and the second cylindrical conductors are electrically isolated.

Abstract: Systems, methods, and apparatus associated for lifting brushes and shorting slip rings are provided. One embodiment may include an actuating mechanism in operable communication with multiple brushes and a plurality of electrical contacts. Each of the brushes may be adapted for selective contact with a respective slip ring of an induction motor. The electrical contacts may be in electrical communication with respective terminals of rotor windings of the induction motor. When the actuating mechanism is actuated, at least a portion of the electrical contacts create electrical shorts between at least a portion of the slip rings and the rotor windings of the induction motor. When the actuating mechanism is actuated, at least a portion of the brushes are lifted from contacting the plurality of slip rings.

Abstract: In one general aspect, various embodiments are directed to an ultrasonic surgical instrument that comprises a handpiece housing that rotatably supports an ultrasonic transducer assembly therein that may be selectively rotated by various motor configurations. Various slip ring arrangements are disclosed for supplying ultrasonic electrical signals and motor drive signals from a control system. Various forms of blade and cutting implements are disclosed for attachment to the ultrasonic transducer assembly such that such implements may be selectively rotatable within a hollow outer sheath. Vacuum may be applied to the cutting implement or through the outer sheath to draw tissue through an opening in the sheath and into contact with the cutting implement.

Abstract: A first slip ring and a second slip ring are put from both ends of a slip ring shaft, respectively, and are attached by shrink-fitting, the slip ring shaft being provided separately from a rotor shaft; the shaft diameter of a lead connecting portion is formed larger than the shaft diameters of respective slip ring attaching portions; and a coupling, which is attached by shrink-fitting to a shaft end portion on the rotor shaft side of the slip ring shaft after the first slip ring is attached by shrink-fitting, is provided.

Abstract: A direct current motor has a wound stator, a permanent magnet rotor having a commutator assembly, and brush gear. The brush gear has a first pole brush, a second pole brush and a plurality of commutating brushes. The commutator assembly has a cylindrical insulating base, and first and second members fixed to the base. The first member includes a radially extending first slip ring and a number of axially extending first bars. The second member includes a radially extending second slip ring and a number of axially extending second bars. The first and second pole brushes make continuous sliding contact with the first and second slip rings respectively. The first and second bars are fixed to the outer cylindrical surface of the base and form a cylindrical surface against which the commutating brushes make sliding contact.