Abstract: A magnetic interrupter type transducer for providing an ignition signal with alternating peaks and varying progressively between the peaks. The shape of the signal is a function of the configuration of the opposed surfaces between a rotor and an adjacent pole tip of a magnetic circuit which generates the ignition signal by electromagnetic induction. The variation in volume of the air gap produced during rotation of the rotor provides the signal of the desired characteristics.

Abstract: A sensor for responding to the rate of change of changing rotational speeds of a rotating vehicle wheel and including a flyweight coupleable for rotation in response to wheel rotation and decoupleable in response to a rate of change of a changing rotational speed of the wheel which exceeds a certain threshold rate. In accordance with the present invention, a brake device is operatively connected with the flyweight for constantly exerting on the flyweight a torque resisting rotation of the flyweight. Provision is made for signalling of any occurrence of an excessive rate of change of rotational speed of the wheel continuously for the interval of time during which a threshold rate is exceeded, and the brake device may be operable in response to such signalling for changing the level of torque exerted.

Abstract: A sensor for responding to the rate of change of changing rotational speed of a rotating member such as a vehicle wheel and including a flyweight coupleable for rotation in response to wheel rotation and selectively decoupleable in response to the exertion on the flyweight of an inertia torque having a magnitude greater than a threshold magnitude due to a change in rotational speed of the member. In accordance with the present invention, control means for exerting on the flyweight torques resisting decoupled rotation of the flyweight takes the form of a restraining mechanism, while signalling of any occurrence of an excessive rate of change of rotational speed of the member is accomplished through a magnetically actuable electrical switch.

Abstract: A crankshaft position transducer system for providing triggering pulses for an electronic ignition system comprising an internal combustion engine having a flywheel, a pair of reference elements mounted at circumferentially and radially spaced locations on the flywheel and a transducer head having two individual transducers. Each individual transducer co-operates with a respective one of the reference elements to produce a triggering pulse.

Abstract: A dynamoelectric machine for generating an electric current having the frequency thereof proportional to the shaft speed of the machine. The generator is preferably of the permanent magnet type particularly suitable for use as a wheel speed indicator or tachometer-generator. The stator has an inner and outer tubular portion, with the inner portion disposed for limited radial movement with respect to the outer housing and having one end of the rotor journalled thereon for holding a substantially constant air gap at the rotary pole thereof. The limited movement of the inner stator portion is resisted by frictional forces created by the permanent magnet and by the axial bias of a thrust bearing. The remaining end of the rotor is journalled in a bearing registered in the outer stator housing. The machine gives magnetic saturation at the stator poles at 30% of rated speed and produces a strong signal output at low speeds.

Abstract: An asynchronous machine including a shaft, a rotor and a stator coaxial with the shaft is provided with a field coil having windings coaxial with and in a plane perpendicular to the machine shaft. The field coil is connectable to a variable DC source for controlling the magnetic flux in the machine. The output voltage of the machine can be controlled without changing the speed of rotation of the machine by controlling the current supplied to the field coil.

Abstract: A Wiegand wire is placed within the magnetic field generated by a first and second permanent magnet. The first permanent magnet has a field strength exceeding that of the second permanent magnet and the polarity of its magnetic field is opposite that of the second magnet. A rotor having segments of magnetic shielding alternating with slots is rotated between the Wiegand wire and the first magnet. When the magnetic shielding is between the first magnet and the Wiegand wire, the latter is exposed only to the magnetic field of the second permanent magnet. In a second position of the rotor, the Wiegand wire is exposed to both magnetic fields. Since the second permanent magnet generates a stronger field than the first, the direction of magnetization in the Wiegand wire changes abruptly causing a pulse to be generated in pick-up coil 4.

Abstract: A variable reluctance pickup for producing electrical pulses in response to the rotation of an adjacent toothed wheel comprises a probe assembly situated tangentially to the path of the wheel teeth. The sensor comprises an elongated core surrounded by a coil and having permanent magnets of opposed polarity at each end of the core. A pole piece extending laterally from one end of the core extends to a point adjacent the path of the teeth of the rotating part. The electrical pulses produced upon part rotation are double the size of pulses produced in the case where only one magnet of equivalent strength to the two magnets is used.

Abstract: Disc type dynamo-electric machine, especially a generator, having two stators and one rotor, an active air gaps between each stator and the rotor, two annular energizing windings in the stators, and two non-active or auxiliary air gaps are formed in a smooth region between the stators and the rotor, the smooth region being closer to the hub than are the annular windings. The entire rotor is formed at least approximately as a disc of uniform strength. The stators are shaped to conform, in the region of the rotor. The magnet flux successively penetrates the two active air gaps and the two auxiliary air gaps and flows in a radial direction mainly by way of the yokes of the stators. Cooling ribs are provided.

Abstract: A device for detecting specific positions of a moving part, for example a rapidly rotating part provided with soft-magnetic projecting elements which alternately pass close to the detector device, which comprises a stationary magnetic exciter circuit for a Hall-effect crystal.The magnetic exciter circuit comprises a single permanent magnet having one pole face oriented towards the moving part, and provided with two symmetrical soft-magnetic pole pieces forming a narrow gap in which the Hall-effect crystal is disposed.

Abstract: A wheel speed sensor including an annular rotor rotatable with a wheel, or the like, has circumferentially distributed surface interruptions. A sensing device fixed against rotation faces the rotor and includes a source of magnetic flux and a coil to generate an electrical signal variable with changes in the magnetic flux through the coil. The sensing device further includes first and second pole members extending from opposite poles of the flux source and spaced so that one pole member opposes a surface interruption on the rotor while the other faces the rotor surface between surface interruptions, and vice versa, to provide a magnetic flux path between the rotating rotor and alternating ones of said first and second pole members. A third pole member extends past the coil and has one end opposing the rotor and wider than the surface interruptions to maintain continuous flux transferring relation with the rotor.

Abstract: For generating control pulses for timing gasoline engine ignition, a rotor of magnetically conducting material with one or more notches in its edge cooperates with a stator also of magnetically conducting material having the configuration of a shallow U, of which the extremity of one leg presents a broad area to the narrow air gap between it and the edge of the rotor and the other leg presents essentially a knife edge. A magnet is mounted on the former leg and a pick-up device, such as a Hall generator, field plate, inductive winding or a reed switch is provided on the other leg to produce an electric signal in response to changes in magnetic flux. The passage of the notch by the broad area foot of the stator produces at most an insignificant change in flux, whereas passage of the notch by the other stator leg produces a sharp change in flux and hence a control pulse.

Abstract: This specification discloses an apparatus and method for providing electrically distinguishable signals occurring as a function of the position of a moving element. It is possible to identify a sub group of electrical signals from the remaining electrical signals or from the entire group. The electrical signals can be used altogether to determine a variable such as revolutions per minute of the movable element or, particular ones of the electrically distinguishable signals can be used for initiating a function such as the firing of spark plugs.

Abstract: A wheel speed sensor including an annular rotor fixed to a wheel for rotation therewith and having circumferentially distributed surface interruptions. A sensing device mounted near the rotor is fixed against rotation and includes a sensing portion opposable across an air gap to the surface interruptions of the rotor to produce a signal representing rotation of the surface interruptions past the sensing portion. The rotor and sensing portion are of complementary generally V-shaped cross section and are separated by a V-shaped air gap such that the output signal is substantially insensitive to relative motion between the rotor and sensing device in an axial plane of the rotor.

Abstract: An engine driven rotor has pairs of arms of different lengths passing by the stator core teeth with respectively different clearances. The stator teeth carry pick-up coils that are connected in series-aiding relation. Although the stator teeth are uniformly spaced, the rotor arms, that are equal in number to the stator teeth, have the longer pair angularly offset from equiangular relation to the shorter pair in such a way that when the rotor moves in its normal direction, a weak pulse is followed by a stronger one and this pattern is repeated four times per revolution. The output of the coils is supplied to a threshold switch, which will be triggered on the second of the pair of pulses at low rotation speeds of the rotor and on the first of the pair of pulses at high speeds.

Abstract: A high speed inductor alternator employs axial air gaps, enabling a nonmagnetic filler in the portion of the gap extending into the solid rotor to be securely bonded to the rotor against the action of centrifugal force. This configuration permits use of axial poles on the rotor, and results in a machine that is substantially shorter, axially, than a conventional radial air gap inductor alternator of comparable output ratings.

Abstract: An electrical speed sensor having a pair of relatively confrontingly rotatable pole members one of which is fixed to the transmission housing of a vehicle while the other members being connected for rotation to a shaft driven by an output shaft of the transmission, characterized by provision of a shaft coupling interposed between the shaft and the said one of the pole mmebers and being rigid in torsion only, to thereby block transmitting of any deflection from the shaft to the said one of the members, with an accurate electric output from the sensor ensured.

Abstract: A compact rotation detecting device in which a rotor providing a set and a reset permanent magnets, a disk providing a plurality of wires having Wiegand effect in the radial direction of the disk, and spiral coils mounted on plural insulating disks are assembled in a housing case in a stack fashion, the spiral coils being automatically connected in series by the assembly, and upon rotation of the rotor pulse frequency proportional to the amount of the rotor's rotation being derived from the series connection of the spiral coils.

Abstract: An electrical power generator employing a helically-vaned in-line rotor in a flow line as a prime mover means and as an integral part of the generator by effecting a cyclic variation in the density of permanent magnet generated flux fields which pass through fixed coil windings. Output voltage magnitude varies with rotor rotation rate which, in turn, varies as the flow rate of gas and/or fluid in the line.

Abstract: A Wiegand wire forms part of a stator coil facing a rotor on which permanent magnets are located. The stator coil has two coil portions or coil sections which are wound or connected to provide opposing inductive outputs upon passage of the magnets in front of the coils to cancel each other, the Wiegand wire change of magnetization providing the additional read-out output, the amplitude of which will be independent of speed, but the recurrence rate will depend upon speed of the magnets passing the stator of transducer.

Abstract: An improved crankshaft trigger wheel for use in an ignition system for an internal combustion engine. The configuration of the trigger wheel provides a high degree of electrical noise immunity, provides a single piece construction which has the dual function of a trigger wheel as well as an engine harmonic balancer. The wheel is made into a configuration which is easily shaped during manufacture, and provides a wheel shape which produces a higher degree of timing accuracy. The wheel of the present invention has an outer, circumferentially extending surface interrupted by corners, with the corners being defined by two adjacent arcs, wherein each arc has a radius which is greater than the radius of a circle described by the rotating wheel.

Abstract: A rotational field, such as is produced by the rotation of a motor vehicle alternator rotor, has placed therein a conductor coil which is cut by the lines of force, or flux lines, of the rotating field. The coil is wound upon a magnetic strip which in turn is wrapped around the housing of the alternator. The rotational speed of the alternator rotor will cause corresponding pulses in the coil which are received by a circuit which utilizes the pulse rate to control an output.

Abstract: Measurement of the current flowing in the rotor of an electrical machine and especially an a.c. exciter with external poles for excitation of a synchronous machine by way of a rectifier mounted on the rotor is accomplished without the use of sliprings by means of at least one pair of contra-wound coils extending in the axial direction of the rotor, the coils being connected in series and mounted in a slotted support of insulation material secured to the underface of a pole shoe in the gap between shoe and a toothed rotor. A voltage proportional to the rotor current is induced in the pair of coils by the stray flux generated by the current carrying conductors in the rotor slots. The width of each coil approximates the width of one tooth on the rotor and the spacing between the axes of the coils approximates the size of the rotor slot pitch.

Abstract: A permanent magnet rotor for a permanent magnet synchronous-run induction-state motor is disclosed. The rotor has Rare Earth magnets disposed in apertures in unitary laminations and parallel to a tangent to the shaft. The magnets are magnetized outwardly so that the direct flux of the magnets is additive to the direct axis flux of the stator at no load. The rotor has a squirrel cage winding and the ends of each magnet aperture are in communication through a flux barrier space to the inner end of an adjacent conductor bar aperture of the squirrel cage winding. The unitary laminations each have an even plurality of radially directed reinforcing ribs disposed along the magnetic neutral axes. The flux barriers are wide relative to the circumferential width of the reinforcing ribs for a minimum of circumferential leakage flux. The leakage flux from one magnet radially through a rib is in opposition to the leakage flux through that rib from the adjacent magnet for substantially zero net leakage flux therein.

Abstract: A homopolar synchronous machine is disclosed which has a substantially lower inertia than equivalent conventional devices. The device includes components for forming a plurality of closed magnetic circuits along the axis of the stator, whereby the inertia is reduced and performance is improved.

Abstract: A pulse generator for the generation of pulses which are synchronously associated with the movement of a mechanical part comprises a toothed element, the teeth of which run past a pick-up head, the pick-up head comprising a first winding fed by a carrier frequency, which produces a field which is modulated by the teeth of the element and a second winding in which a voltage is induced by the modulated field, the induced voltage is supplied to a phase discriminator which produces a pulse sequence having a keying ratio proportional to the relative phase position of the induced voltage and the carrier frequency and the pulse sequence is fed to an integration element which produces a voltage signal proportional to the keying ratio.

Abstract: To suppress stray noise pulse in inductive pick-ups located in magnetic relation to a rotating body, typically the flywheel of an internal combustion engine, so that the instantaneous shaft position can be accurately determined, to accurately compute an ignition instant, fixed or stationary pick-up transducer is formed with an E-shaped core having outer legs and a central leg, the pick-up coil being wound on the central leg, and the magnetic element, typically a permanent magnet rotating with the shaft of the engine, having a width to match essentially only the width of the central core and passing in a plane transverse to the plane of the core, so that the outer legs of the core will act as shields against stray noise pulses. The core can be constructed as a circular element of a central core within a tubular magnetic structure, the E-shaped configuration being obtained by slotting the outer tubular structure.

Abstract: An improved electromagnetic scanner has a substantially E-shaped core having an outer surface that is positioned, at a predetermined air-gap spacing, from a regularly grooved ferromagnetic surface of a textile machine. A pair of coils extend around the crosspiece of the core between the outer arms of the core and the middle arm thereof, such coils being connected in series and connected to a bridge circuit to generate an electrical indication that varies at the rate of movement of the grooved ferromagnetic surface past the core in a direction crossing the grooves in the surface. The plane of said core is oblique to the grooves. A pair of abrasion-resistant, non-magnetic contact elements supported in the spaces between the arms of the core, projecting outwardly into the air gap, and are urged into contact with the moving ferromagnetic surface by a spring carried in a housing in which the core and coils are mounted.

Abstract: A wheel speed sensor for a vehicle adaptive braking system is installed within the vehicle hub cap so that the hub cap and speed sensor assembly are installed on the vehicle wheel as a unit. The speed sensor includes a rotor assembly which is rotatable with the hub cap, and a stator assembly which includes a bearing which slidably and rotatably receives a spindle which is integral with the hub cap. A tang projects from the stator assembly and is received in a corresponding slot on the vehicle axle to prevent relative rotation between the sensor assembly and the axle. A spring is provided which rotates with the hub cap and which yieldably urges the stator into engagement with the end of the vehicle axle. Consequently, the hub cap and sensor assembly are installed and removed from the vehicle as a unit, thereby facilitating installation of the sensor assembly since the air gap between the stator and the rotor may be set at the place of manufacture of the sensor assembly.

Abstract: An apparatus for generating a pulse train depending on the speed of a rotary system. The external field of a coupling magnet in a slipping clutch in the rotary system is sensed to provide a measure of speed.

Abstract: A rotation indication system having an improved sensing device for determining the velocity of a rotating body is disclosed. The improved sensing device is tubular in configuration and includes a source of magnetic flux and two pole pieces that define a split magnetic field. The sensing device is mounted in close proximity to a rotor which is connected to the rotating body. The rotor has apertures which interrupt the split magnetic field producing an output signal with a frequency proportional to the velocity of the rotating body. The sensing device is oriented relative to the rotor apertures so that each pole piece is alternatively in register with an aperture to produce the desired output signal. Since the sensing device is tubular in shape, it can be rotated about its axis to obtain the desired orientation with the rotor apertures, thus permitting the use of the sensing device with a wide range of rotor diameters having various aperture spacings.

Abstract: A variable reluctance electrical generator is disclosed having a unique structure which, for any given design parameters, tends to maximize air gap areas and thus minimize mmf drops thereacross. The mean magnetic flux paths all generally include a constant reluctance parasitic air gap and a variable reluctance active air gap. The portion of the magnetic circuit defining the active air gap is adapted to magnetically saturate before the portion of the magnetic circuit defining the parasitic air gap areas thus eliminating the parasitic air gap as a design limitation. In the exemplary embodiment the parasitic air gap is located radially outwardly of the active air gap areas such that the parasitic gap reluctance is much less than the minimum active gap reluctance. The design of the alternator is also such as to simplify its assembly during fabrication and to thereafter permit ready disassembly of its major components from one another for repair or other purposes.

Abstract: A three-phase permanent magnet alternator is disclosed employing a fractional pitch stator winding of about two-thirds or 120 electrical degrees for minimizing third harmonic circulating current in the phase windings. The alternator has a rotor supporting permanent magnet poles and a slotted stator having coils disposed in the slots with the pitch of each coil being less than the rotor pole pitch and the coils of each phase connected in series to form a fractional pitch phase winding. The rotor circumscribes the stator and the permanent magnet poles have an arcuate extent nearly as great as the rotor pole pitch.

Abstract: A wheel speed sensor for a wheel mounted on the end of an axle shaft of a drive axle can be utilized in an anti-wheel lock brake control system. The sensor includes an electromagnetic sensing device which is mounted on the drive axle housing in alignment with the axle shaft inwardly of the wheel. An excitor rotor of the sensor is preferably mounted on the differential casing about the axle shaft in alignment with the sensing device for rotation while maintaining the distance between the sensing device and the rotor within a predetermined limit without allowing contact therebetween. A C-shaped spring partially encircles the rotor as a pair of tabs at its ends extend inwardly through the rotor to make contact with a corresponding pair of grooves in the axle shaft. The C-shaped spring member drives the rotor in response to rotary movement of the axle shaft but allows removal of the axle shaft for maintenance while the rotor is retained within the protective interior of the housing.

Abstract: A non-elastomeric sensor holding fixture using metal-to-sensor contact friction in a wheel slip control system maintains a wheel speed sensor in intimate contact with an exciter wheel without the excessive sensor wear which otherwise happens when the wheel speed sensor is held in place with resilient elastomeric holder. The use of metal-to-sensor frictional contact in the holding fixture avoids the hardening and seizing normally occurring in elastomeric-to-sensor frictional contact due to time and allows readjustment of sensor position after extended use.

Abstract: A rotatable clock disc of soft magnetic material has one or more teeth arranged in an asymmetrical graduation at the periphery for use as a pulse generator with a field plate differential sensing component. Each tooth is in the form of a flap formed by a pair of radially extending cuts spaced apart an interval greater than the width of the sensing component. The flap is bent so as to extend generally parallel to the plane of the disc and provides balance of the disc when rotated.

Abstract: A device for determining the angular position of a rotating part includes first and second parallel arranged magnets forming a symmetric magnetic excitation circuit with a Hall-effect element disposed on the axis thereof. The rotating part has first and second elements made of a soft magnetic material which are angularly displaced so as to alternately pass by the first and second magnets, respectively, to produce first and second oppositely directed transverse magnetic field components, H, at the Hall-effect element which thereby generates a signal whose polarity reverses to indicate angular position of the rotating part.

Abstract: A speed detector, particularly useful on a permanent magnet DC motor, for providing a pulse indication from movement of the rotor teeth. During one revolution of the motor, a pulse is provided for each motor tooth. In a preferred embodiment, the pulse pickup probe is formed from a ferromagnetic stud which is anchored to the stator housing and extends through an opening formed in the center of the fixed permanent magnet to a position in close proximity to the rotor. The magnet through which the probe extends provides magnetic flux having a path through the stud and the rotor. The reluctance of the flux path through the rotor varies as a function of the alignment of a rotor tooth with respect to the ferromagnetic stud. The stud is formed to have a pickup end facing the rotor. The diameter of the pickup end is slightly greater than the rotor tooth width. A pickup coil is wound around a reduced diameter portion formed on the ferromagnetic stud, and generally lies within the opening through the permanent magnet.

Abstract: A measuring sensing device for generating a signal corresponding to the relative rotation between two construction parts, with a rotor arranged on the rotating construction part and a stator borne on the fixed construction part, the stator being supported by one or more clamping bodies on the fixed construction part in such a way that on overcoming a considerable frictional adhesion it is slidable with respect to the fixed construction part.

Abstract: An inboard type sensor for a vehicle anti-skid system is mounted adjacent a wheel assembly and disposed within an annular bored housing. The housing has situated therein a split tubular springlike sleeve which is adapted to exert a radially inward compressive force upon the sensor thus preventing the sensor from undesirable axial or rotational movement after the sensor is properly positioned. The sleeve is locked within the bushing to prevent its axial or rotational movement relative to the housing.

Abstract: In a bearing assembly having at least two relatively rotatable members, a device having means for generating a magnetic field and means for sensing variation in the magnetic field, said bearing assembly including means for inducing variations in the magnetic flux which variations have a frequency proportional to the rotational speed of one member relative to other member, said inducing means being associated with one of said members and said means for sensing variations being associated with said other bearing member and seal means partly defined by said members completely sealing said inducing and sensing means.

Abstract: Two yokes of magnetic material are fixedly attached to opposite axial ends of a magnet which is revolvable about its axis with a revolving shaft, an alternating magnetic field generator is positioned in the magnetic field between the two yokes to generate alternating magnetic field with revolution of the shaft, and a magnetoelectric transducer is provided in the alternating field in order to generate a pulsating electrical signal indicative of the number of the shaft revolutions.

Abstract: A magnetic pickup for sensing the speed of a rotor disc having a nosepiece affixed to the disc containing one or more magnets. The magnets are contained within blind openings passing inwardly from the back of the nosepiece and arranged to position the magnets within an embossed section extending axially from the outer surface thereof. A stationary sensing probe is mounted adjacent to the embossed section which is capable of generating a voltage signal as the magnets are passed in close proximity with the sensing element.

Abstract: A speed sensor comprises a pick-up device mounted on the aluminum casing of a vehicle transmission, adjacent an existing ferromagnetic gear inside the transmission casing, which gear rotates in unison with the driven wheels of the vehicle. The pick-up device comprises a permanent magnet and a toroidal ferromagnetic core on which an inductive coil is wound. The permanent magnet and toroidal core are cooperatively arranged with respect to the ferromagnetic gear such that a magnetic circuit is created from the permanent magnet through the toroidal core, through the transmission casing, and through the ferromagnetic transmission gear back through the transmission casing to the permanent magnet. As the gear rotates, the reluctance of the magnetic circuit is varied at a rate representative of the speed of the gear and hence the speed of the vehicle. The speed information is provided across the inductive coil.

Abstract: In order to facilitate the automated assembly of an electric motor, all of the major components and sub-assemblies thereof are successively brought together in one axial direction.

Abstract: A bracket for mounting a wheel speed sensor module to a vehicle axle. The bracket is a stamped metal part including a central portion which is secured to the axle and end portions for mounting the sensor module. A tab formed integrally with the central portion of the bracket locates the bracket on the axle.

Abstract: The motor has a first element carrying toothed studs and windings mounted on the studs and a second element constituted by a mass of magnetic material on which second element there are formed teeth capable of effecting a relative movement with respect to the teeth of the first element, the number of teeth of the first element being different from the number of teeth of the second element so that said teeth are capable of modifying the reluctance of the magnetic circuits that they constitute respectively with said studs, in order to produce a relative movement of the two elements when the windings are supplied with a poly-phase current. The number of teeth of the two elements satisfies the following relation:.vertline.Z.sub.I - Z.sub.II .vertline. = skin which:Z.sub.I = number of teeth of the first element including fictive teeth which may be assumed to be located between the studs;Z.sub.

Abstract: A rotation indication system having an improved sensing device for determining the velocity of a rotating body is provided. The improved sensing device is tubular in configuration and includes a source of magnetic flux and two pole pieces that define a split magnetic field. The sensing device is mounted in close proximity to a rotor which is connected to the rotating body. The rotor has apertures which interrupt the split magnetic field producing an output signal with a frequency proportional to the velocity of the rotating body. The sensing device is oriented relative to the rotor apertures so that each pole piece is alternatively in register with an aperture to produce the desired output signal. Since the sensing device is tubular in shape, it can be rotated about its axis to obtain the desired orientation with the rotor apertures, thus permitting the use of the sensing device with a wide range of rotor diameters having various aperture spacings.

Abstract: An ac generator for a vehicle in which a stator frame having a stator core fixed thereto and supporting a rotary shaft therein is composed of a pair of end covers of steel plate and a cylindrical casing of steel plate, and the end covers, cylindrical casing and stator core are integrally connected together by welding so as to ensure a high mechanical strength.

Abstract: The tone wheel is a heavy walled steel stamping having a flanged central opening adapted for pressing on to a pilot turned on the outside surface of the wheel hub, and a cylindrical flange contiguous to the usual offset portion of the brake disc and having teeth formed on its inside surface. The spaces between the teeth are filled with adhesive nonmagnetic material so that the tooth tips and the nonmagnetic material provide a smooth unbroken cylindrical surface. A radial adjustment for establishing a predetermined clearance between a pickup and the tone wheel is provided by a generally rectangular projection on the back of the pickup which fits into an elongated slot in the pickup bracket. The output of the pickup is used to control the adaptive braking system.