Abstract: The invention relates to an electronic instrument for use on a bicycle and intended to indicate to the bicycle operator measuring values like actual speed or actual distance covered by the bicycle. The electronic instrument is provided with two signal receiving components on both sides of the middle plane so that the instrument can be mounted on both sides of the respective wheel of the bicycle.

Abstract: Magnetic poles are provided continuously with a pitch .lambda. on the peripheral portion of a drum rotated in accordance with a movement of a moving body. A magnetic sensor is provided in opposition to these poles. The sensor is formed of two magnetoresistive element pairs which are spaced from each other at .lambda./6, and the two elements in each pair are arranged in positions spaced from each other at .lambda./2. The two elements in each pair are connected in series to form a bridge circuit. The signals obtained from the nodes of the series-connected elements in the two element pairs are differentially amplified so that third harmonic wave components are eliminated, and a signal having no distortion and representative of the position or speed of the moving body can be obtained.

Abstract: An electromagnetic power generating type rotation sensor has a magnetic pole which is divided into an inner magnetic pole piece and an outer magnetic pole piece (3a, 13a) located in a position close to an outer peripheral part or a side part of a magnetic rotator. The inner magnetic pole piece (3b, 13b) is located adjacent to the outer magnetic pole piece but inside the sensor so as not to be exposed to the external environment.

Abstract: This invention relates to a multi-phase printed circuit board (PCB) tachometer for accurate measurement of the rotational speed and direction of an electric motor. The multi-phase output not only provides rotation velocity in the form of the conventional a-c output signal, but also provides rotation direction information, in addition to providing a higher rotational resolution than conventional PCB tachometers. According to a first embodiment of the present invention, a multi "winding", multi-phase PCB tachometer that uses a single multi-pole magnet is constructed by using double sided boards with plated through holes. In a second embodiment, a multi-phase tachometer configuration is disclosed in which the number of radial printed circuit traces and the number of pole magnets are not equal, whereby the individual voltages generated across each radial segment will not be in phase, and thus can provide rotational direction information as well as velocity information.

Abstract: The generator wheel is composed of a tooth part and of a marker part. The tooth part has a rotational axis and a coaxial tooth or toothed edge in the shape of a circular ring with teeth situated distributed over its circumference, some of said teeth being marker teeth which include a recess. The marker part is secured to the tooth part and contains sheet metal strips corresponding in number to the number of marker teeth, said sheet metal strips projecting into said recesses of the marker teeth. Marker part and tooth part are composed of materials having different eddy current losses.

Abstract: A device for detecting a rotating speed of a wheel of a vehicle, including an axle hub having a shaft portion, and a flange portion which extends radially outwardly from one of opposite ends of the shaft portion such that the wheel is secured to the flange portion. The shaft portion has an intermediate section at which the axle hub is rotatably supported by a stationary member via a bearing. The detecting device further includes a rotor secured to a part of the shaft portion of the axle hub remote from the flange portion so that the rotor is rotatable with the wheel. The rotor has an externally toothed section which has a multiplicity of teeth spaced apart from each other in a circumferential direction of the rotor. A speed detector is supported by the stationary member, so as to detect the teeth of the toothed section of the rotor during rotation of the rotor. A covering member attached to the stationary member cooperates with the same to cover the rotor.

Abstract: To provide an unambiguously representative signal responsive to the speed of a vehicle wheel, an inductive pick-up (1a. . . . 1n) is coupled to a suitable star wheel or the like of each one of the wheels, the pick-ups then providing their signals to amplifiers (3a. . . . . 3n) having hysteresis characteristics. At low speeds, an offset signal is superimposed on the voltage from the inductive pick-ups so that the amplifiers respond and provide output signals only at higher amplitudes of the pick-up signals, thereby eliminating inaccuracies or disturbances occurring in the sensor which might simulate changes in speed of the respective wheel.

Abstract: A timing arrangement incorporates a timing disk having absolute marks arranged about a circle and serving for the identification of the angular position of the shaft of an internal combustion engine. The marks include a code track havig code marks and absolute marks, each absolute marks being preceded by a code element comprising a number of code marks. Each absolute mark is identified by a code section preceding and consisting of two or more code elements.

Abstract: A speed detection apparatus intended to be placed in a borehole containing high temperature flowing fluid consists of an elongated casing with a rotary shaft having a helical rotary blade in the casing. Secured to the rotary shaft is a sensor control rotor with a plurality of metal targets on the periphery. Opposed to these targets is an eddy currents displacement transducer with electric circuitry including a coil. The displacement of the targets due to fluid flow causes impedance change in the coil which produces an electrical signal proportional to the rate of flow.

Abstract: A vehicle tachometer kit including a pick up coil that is adapted to be mounted on the outside of the vehicle's alternator to sense its rotating field without any disassembly. An induced signal in the coil from alternator field leakage provides the normal input to a user calibrated r.p.m. display driving circuit in the tachometer that can be calibrated for different alternators and drive pulley ratios without another tachometer by selectively applying a simulated input reference signal to the display driving circuit and adjusting the r.p.m. display until a scheduled ratio is achieved between the displayed r.p.m. and the reference signal.

Abstract: A motion measurement device, more particularly designed for measurement of a rotation of a body around an axis. This device comprises a coded wheel drivably connected to said body for rotation and comprising a plurality of holes regularly distributed around said axis. Said holes are binary digits and for one digit is constituted by a simple hole passing through the wheel and, for the other, an open hole connected to the nearest edge of said wheel by a narrow slit. A sensor placed on the path of the holes and comprising two coils facing one another allows determination of the distance travelled by the moving body connected to said coded wheel. The speed and acceleration of the moving body can also be determined.

Abstract: A built-in wheel speed sensor structure having an internal gear-like sensor rotor integrally fixed to a tire and an electromagnetic car speed sensor fitted to an inner portion of a parking brake and facing the sensor rotor. The wheel speed sensor is supported by an anchor pin of the drum brake so that the sensor rotor may be positioned away from service holes for fastening bolts which have been bored into a brake drum.

Abstract: A tubing trip tool for use in determining the extent of defects in tubular elements comprising a continuous string used in a subterranean oil or gas well during removal of the string from the well is disclosed. Local defects and axially extending defects, as well as the average wall thickness of the tubular elements, are measured. The position of the defects is determined by measuring the variable velocity of the tubular elements as they are removed from the well. A noncontact velocity detector comprises detector elements generating a first signal dependent upon an applied magnetic field and the velocity of the tubular elements. The first signal is compared to a signal dependent only upon the magnetic field generated in a second element. A pickup coil and Hall effect probes can be used.

Abstract: An electromagnetic pickup includes an insulating body that mounts a coil of wire surrounding a spool portion at one end of the body. A magnetic element is disposed within an axial passage through the body, including its spool portion. A sleeve-like molded plastic cover surrounds the spool portion and other portions of the body, and an encapsulation occupies the spaces within the cover that are not occupied by the body and elements mounted thereto. One end of the magnetic element extends to one end of the body and abuts the inner surface of the wall that encloses one end of the cover. The other end of the body is provided with a self-centering flange that engages the inner surface of the cover, and the other end of the cover is provided with the flange that is embedded in the encapsulation that also forms a seat external of the cover.

Abstract: A metal detector circuit comprising an oscillator capable of sensing any type of metal in motion over a predetermined frequency. The oscillator supply voltage is derived from a feedback correction circuit which compensates for stationary metal as well as metal moving in a lower frequency past the sensing coil of the oscillator by adjusting the supply voltage of the oscillator to make up for Q losses. The higher frequencies are blocked by a DC time constant (low pass filter) and the sensor coil is able to see through stationary metal and detect a moving metal target on the other side thereof. The amplitude of the modulated signal from the oscillator remains nearly constant throughout its detection range by this supply voltage feedback correction circuit. The detection circuit also provides a reliable output signal indicating when the sensor portion is damaged due to an open or shorted coil circuit.

Abstract: Wheel bearing pulser combinations of the type where an annular pulser is force fitted onto the outer surface of a wheel bearing are disclosed in which the pulser is constructed to accommodate resiliently resisted radial expansion of its central opening as required by the force fitting of the pulser onto the bearing to permit increased dimensional tolerances of the bearing while avoiding an undue radial compression of the outer race of the bearing from the force fit.

Abstract: Device for a drive for storage media for the generation of at least one index pulse per revolution of a rotating element with a generator, which, during operation, for each revolution of the rotating component, generates at least one signal pulse that alternates once between two polarities, and with an evaluating circuit activated by these alternating signal pulses to generate the index pulses at its output. The evaluating circuit includes a comparator with asymmetrical hysteresis with two inputs and one output, between the two inputs of which comparator the output signal of the generator lies, and the hysteresis of which is tuned to the generator output signal such that the comparator output sharply changes from a first to a second potential when the amplitude of the signal pulse at a preset polarity exceeds a preset switching voltage value, and sharply returns from the second to the first potential when the signal pulse passes through its zero crossing from the preset to the opposite polarity.

Abstract: A sensor for magnetizable materials is comprised of an inductive component and an evaluating circuit. The inductive component is constructed by thin-film techniques. The core is made of a ferromagnetic amorphous metal. Such a sensor can detect the presence of magnetizable materials with very high position accuracy. The sensor is employed in revolution counters and in angular-displacement transducers.

Abstract: In an MWD measurement system, the speed of rotation of a downhole turbine is measured by the interaction of a triaxial magnetometer in a sensor package and a permanent magnet attached to the turbine shaft. The triaxial magnetometer may be part of an existing MWD system for measuring borehole directional parameters. The magnet is a strong magnet mounted on the turbine shaft perpendicular to the axis of the turbine and the axis of the drill string.

Abstract: A displacement measuring device, using an incremental code, which includes a coding member (22) resting on the object (21) to be measured and having a coding section for generating such signals that a sensing element can discriminate the signals as 0 or 1, sensing means (25A, 25B) disposed to sense the coding section of the coding member for producing sensed signal in response to the displacement of the coding member (22), and rectangular wave-converting circuits (27A, 27B) for receiving and converting the sensed signal into rectangular wave signals. A clock pulse generator (28) is provided in the device for generating a clock pulse with a higher repetition-frequency than the repetition-frequency of the sensed signal.

Abstract: A contactless control device for a press having a device for checking whether an abnormality detector normally operates or not. The device of this invention is constructed to operate when power is fed to the press or when the press is stopped at its top dead center. A self-check operation generates and applies a dummy pulse to the abnormality detector. The abnormality detector generates an error signal corresponding to the dummy signal if normal. Since no error signal is generated when the abnormality detector is abnormal, the press is not operated. Operation of the press is dependent on the error signal. Whether the abnormality detector is normal or not is indicated during a self-check operation.

Abstract: A coil sensor excited with alternating current and connected in a circuit for detecting changes in the coil impedance producing a signal exceeding a fixed threshold value in response to the revolution of a wheel with features providing periodic changes in the spacing between the coil and the wheel, has its periphery subdivided into zones where the surface material is alternately thereomagnetic and non-theromagnetic. With a suitable setting of the frequency of the exciting alternating current and a suitable choice of the materials with respect to their eddy current and magnetic induction effect on the inductance of the coil, it is possible to suppress the signal of once per revolution periodicity resulting from wheel eccentricity, bearing wobble or the like.

Abstract: A flat coil velocity transducer includes a thin, flat coil mounted to a member whose velocity is to be measured. The convolutions of the coil are skewed so that regions at opposite ends of the coil contain predominantly upper or lower legs of the convolutions. The coil moves transverse to a magnetic field to induce voltage in the legs of the coil. However, the field induces voltage in one, but not the other, end region so that a resultant voltage is induced in the coil dependent on the strength and direction of the magnetic field, the number and length of the legs in the region, and the direction and velocity of movement.

Abstract: An operational amplifier is used as a threshold switch and an inductive generator that provides a wave used for timing operation of the threshold switch also feeds a circuit that produces a reference current corresponding to the average absolute magnitude of the generator voltage, which, in turn, is fed to at least one current mirror, the output of which is used to shift the operating threshold of the operational amplifier. A second current mirror is used in alternation with the first for half-waves of the generator voltage which are of opposite polarity and a positive feedback connection around the operational amplifier provides a switching characteristic having an appropriate amount of hysteresis so that the inherent timing shift is compensated on switching in response to both positive-going and negative-going portions of the generator output wave.

Abstract: Apparatus for detecting at least one predetermined angular position on rotating devices, having a tachogenerator with a stator part and a rotor part for producing a tacho signal with speed-dependent frequency. The stator and rotor parts of the tachogenerator form at least four circumferentially directed, substantially equidistantly spaced pole areas. For the purpose of an angular position-dependent amplitude modulation, a pole clearance is provided in at least one of the pole areas in both the stator part and the rotor part of the tachogenerator. An envelope amplifier with a threshold value stage is preferably connected in series with the tachogenerator and essentially only permits the passage of the angular position signals resulting from the coincidence of pole clearances in the rotor and stator parts of the tachogenerator.

Abstract: A rotational speed sensor (10) comprising a shaft (54) having a reluctor (50) mounted thereon and coacting with a complementary shaped stator (18). The reluctor (50) and stator (18) have coacting regularly spaced projections (20, 58) which are magnetizable so that as the reluctor (50) rotates with the shaft (54), there is developed a cumulative voltage output which in turn enables utilization of much greater air gaps between the respective projections (20, 58). Because of the greater latitude in the air gaps, it is possible to construct a variable reluctance speed sensor (10) much more economically and with less emphasis on cumulative manufacturing tolerances. This greater flexibility of manufacturing with higher manufacturing tolerances contributes materially to the attainment of an economical and reliable speed sensor.

Abstract: A system for detecting the rotational speed of a rotating body comprising the steps of generating two kinds of signals A and B having alternating wave forms and corresponding to the rotational speed of the rotating body by means of position-detecting devices (5a, 5b), the signals A and B having the same amplitude and having phases deviating by 90.degree.

Abstract: A magnetic sensor mounting device is used in a wheel speed sensor assembly which has an annular rotor coaxially aligned with and connected to the wheel for rotation therewith and a generally cylindrical magnetic sensor to be fixedly mounted on the axle assembly. A support structure for the magnetic sensor includes a resilient plastic sleeve member which is generally cylindrical to closely encircle the magnetic sensor. An adjusting nut of the support structure acts on a tapered end of the sleeve member to inwardly wedge the sleeve member against the magnetic sensor to produce frictional contact therebetween for retention of the magnetic sensor at a desired axial location.

Abstract: An apparatus is disclosed for mounting a rotational signal transducer on a rotary shaft where the transducer generates a signal proportional to the shaft's rotational velocity. The apparatus includes a gear mounted for rotation with the shaft. A support platform is rotatably secured to the shaft by a roller bearing. The roller bearing permits the shaft and platform to rotate relative to one another but prevents relative axial motion between the shaft and platform. A transducer is mounted on the platform and operably aligned over the gear and generates a signal as gear teeth pass the transducer. A torque rod pivotally fixed to both the platform and a stationary support restrains the platform from rotating with the shaft. The pivotal connections of the torque rod permit the platform to move axially with the shaft.

Abstract: The disclosure is directed to an improved electrostatic latent image developing method in which uneven development arising from simultaneous employment of a magnetic roller rotational driving system and an AC developing bias impressing system is eliminated, without impairing the advantages available from such systems, so as to make it possible to provide developed images of good quality at high density in the application, for example, to an electrophotographic copying apparatus and the like.

Abstract: Apparatus for generating a signal corresponding to a reference phase of a reference rotor of a motor relative to the stator, includes a field magnet having a plurality of north and south poles mounted on the rotor; a Hall-effect element associated with the field magnet and mounted on the stator for generating a position signal corresponding to the position of the rotor relative to the stator for use in changing-over energization of coils on the stator; a plurality of equally spaced cut-out portions along the periphery of the rotor forming a plurality of equally spaced toothed portions; an optical detector associated with the toothed portions and mounted on the stator for generating a speed signal corresponding to the rotational speed of the rotor relative to the stator; a differentiating circuit for differentiating the position signal to produce a differentiated signal; and an AND gate supplied with the differentiated signal and the speed signal for producing the phase signal corresponding to a reference phas

Abstract: A rotational speed indication signal generator comprises a magnetic circuit and a plurality of generating coils radially arranged with respect to the rotary shaft of a rotor. Each of the generating coils is wound around a radial projection of a circular disk made of a magnetic material so that the axis of the generating coils is normal to the rotary shaft. The generating coils are electrically connected in series in such a manner that a noise voltage induced across one coil caused by external flux has opposite poloraity to that of a noise voltage induced across another coil positioned opposite with respect to the rotary shaft. The electrical connection of the generating coils has a given circular direction while a lead wire connected to the last coil in the series connection has a circular direction opposite to the direction of the series connection.

Abstract: A rotation detecting apparatus includes a transformer consisting of a primary coil disposed to be energized by an energizing source and two secondary coils connected in opposite polarity to each other on the longitudinal sides of the primary coil. The magnetic coupling of the transformer is changed in response to the rotation of a rotating body and this changes the phase of the composite voltage signal of the secondary coils. By virtue of this construction, not only the rotation of the rotating body can be detected at low rotational speeds, but also the rotation can be detected accurately without being affected by the ambient temperature.

Abstract: A hydrostatic-mechanical drive for a load, e.g. a self-propelled machine such as a concrete mixer comprising a hydrostatic motor which can be connected to the load via a mechanical transmission. According to the invention, the shaft of the hydrostatic motor extends into the control plate or cover thereof (through which hydraulic communication is made with the drum carrying the axial pistons of the motor) and is provided with an inductive sensor on this plate to form a pulse generator (with a metal gear on the shaft) whose output represents a parameter of rotation of the motor.

Abstract: A speed detector including a circular rotational member having a plurality of equally spaced-apart teeth on the outer circumference thereof, and first and second magnetic sensors. The first and second magnetic sensors each comprise a permanent magnet, a magnetic pole which permits the passage therethrough of a magnetic flux generated by the permanent magnet, and a detection coil wound on a portion of the magnetic pole. The magnetic poles of the first and second magnetic sensors are disposed in close proximity to, and arranged to face, the teeth on the rotational member, whereby each magnetic sensor produces an alternating output signal as the rotational member rotates, the frequency of each output signal being proportional to the speed of the rotational member.

Abstract: An impact wrench having an adaptive control system for determining the yield point or some similarly significant point of a fastener assembly by detecting a signal representative of the peak deceleration of the hammer, one embodiment of which is the peak recoil value of the hammer after impacting with the anvil of the wrench, and a signal representative of the angular displacement of the output shaft of the wrench. Yield of the fastener is determined when the respective magnitudes of successive deceleration signals do not exceed the magnitude of a previously stored maximum deceleration signal by a predetermined fixed amount. Upon attaining the yield point or other similarly significant point, the wrench may be allowed to rotate the fastener an additional preselected number of degrees before shutting off.

Abstract: To positively allocate output signals from a transducer scanning marker elements arranged at a uniform distance from the center of a rotating disk, the markers are located around the circumference of the disk in accordance with a predetermined pattern, for example, uniformly distributed 30.degree. apart, or distributed with uniformly increasing relative distances, and an additional market element (33) and forming a reference marker is located in the zones between adjacent markers spaced from a neighboring marker element (21) of the plurality of marker elements by a distance which is substantially larger than the angular distance with respect to the marker element at the other side of the reference marker. The outputs from a pick-up sensor are evaluated by applying the outputs to two counters, counting a different clock rate, the count output of one of the counters being stored and compared with a subsequent count state of the other counter operating at a higher clock rate.

Abstract: An apparatus for detecting displacements of existing movable bodies made of ferromagnetic materials and magnetized by external magnetic fields, comprising a magnetic sensor disposed in the vicinity of the movable body for detecting change in the magnetic field caused by the motion of the body, and a processor for converting the outputs of the magnetic sensor into pulse signals.

Abstract: A magnetic rotary encoder for detecting incremental angular displacement, angular velocity and rotating direction using magneto-resistors is disclosed. A drum, disk or cupshaped rotary member is attachable to a rotatable shaft. A magnetic medium is provided on a surface of the rotary member and is divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded. The magnetic medium produces an alternating magnetic field as the rotary member revolves. Alternatively, a plurality of permanent magnets are provided on the surface of the rotary member to produce the alternating magnetic field of the rotary member revolves. A magnetic field detector includes at least one magneto-resistor having a stripe-like configuration with width D. The magneto-resistor is located in the vicinity of the rotary member so as to be spaced from the magnetic medium or the permanent magnets by equal to or less than p at its nearest portion and by equal to or less than 20p at its furthest portion.

Abstract: A pickup probe for engine timing which is responsive electrically to an indicator on a rotating engine part. The free end of the probe is adapted to extend through an access opening in an engine member into proximity with the indicator on the rotating engine part. A sensor is contained within the free end portion of the probe. The probe includes a mounting means adapted to be detachably secured to the engine member adjacent the aforesaid access opening.

Abstract: An amplifier circuit for use with Hall effect and other similar type sensors whereby the circuit is conditioned by the cyclical signal input from the sensor and sets a threshold level based upon the signal input from the sensor, so that the signal output from the circuit is a voltage replica of the input signal, but modified to have a predetermined and constant high and low peak values without regard to peak value variations of the cyclical input signal.

Abstract: A speed measuring sensing device for producing a signal corresponding to the relative angular rotation between two structural members including a rotor arranged on the rotating member and a stator mounted on the stationary member. The stator is separated from the rotor by an air gap. The rotor includes a plurality of magnetizable sectors which vary the magnetic field while passing a pole shoe of the stator. The surface area of each of the magnetizable sectors of the rotor and the surface area of the pole shoe of the stator exhibit a maximum ratio of 1 to 1.

Abstract: The invention relates to a device for measuring the angular position of a gear in a digital ignition system of an internal combustion engine, wherein an origin sensor responsive to the passage by of a pre-set tooth of a gear, is connected to one of inputs of a pulse former having a second input to which an output of a rectifier and filter circuit is connected; and an input of the rectifier and filter circuit is coupled to the output of an angle pulse sensor.

Abstract: A rotating speed detecting device of a turbocharger comprising the compressor wheel and the turbine wheel which are fixed onto the opposed ends of the rotary shaft. A hole is formed on the central portion of the shaft. An electromagnetic detector is arranged in the vicinity of the central portion of the shaft so that the detecting head of the detector can face the hole of the shaft.

Abstract: Input variables are varied cyclically and sequentially in the same direction until the sign of the differential quotient of the magnitude of the error with respect to time changes.

Abstract: Bearing assemblies with inner and outer races and rolling elements therebetween incorporate local sensing means for producing a signal indicative of the movement of one of the races relative to the other. The sensing means is mounted in close proximity to one of the races and is usually directly secured to the race intended to be stationary. The sensing means can be mounted laterally of the bearing races or radially inside or outside of the bearing races.The sensing means may employ an inductive or capacitive sensor and oscillatory means and a body or component, such as a disc, carried by the movable race creates an influence detected by the sensing means to provide the signal. In other constructions the sensing means detects changes in electromagnetic radiation or fluid pressure created by the component or body carried by the movable race.

Abstract: A signal conditioning circuit for the output of a magnetic position sensor is disclosed. The magnetic sensor generates a total output signal that increases as a function of the rotational velocity of the sensor with a spurious noise component that is a relatively constant percentage of the actual signal voltage over the speed range. In a preferred embodiment, the signal conditioning circuit discriminates between the noise component and the signal component by comparing the total signal to a variable threshold only after a positive going zero cross. The variable threshold is generated as a function of the peak amplitude of the total signal. In a second embodiment the signal conditioning circuit includes gain control means which varies the amplitude of the total output signal as a function of its peak to maintain the threshold above the noise component.

Abstract: A system for indicating measured values, particularly the speed of movement of a motor vehicle, includes a pulse generator generating pulses having a frequency corresponding to a measured value, a counting circuit including first and second counters for counting pulses generated during successive time intervals to produce a pulse count signal for each time interval, a comparator comparing the pulse count signals from successive time intervals to produce a pulse difference signal corresponding to the difference therebetween, a memory for storing the pulse difference signal and transmitting the pulse difference signal to a stepper motor, and a pointer driven via gears from the output of the stepper motor to produce an indication of the measured value.

Abstract: A probe assembly for measuring the speed of rotation of a gas-turbine engine compressor shaft has a sensor head mounted at one end of a tubular probe body by means of a bellows unit which permits limited axial displacement of the sensor head relative to the probe body. The sensor head has a sleeve sealed to its rear end, one end of the bellows unit being sealed to the sleeve and the other end being sealed to the probe body. The forward end of the probe body extends through the bellows unit and into the sleeve where it is resiliently coupled with the sensor head by a helical spring. Four outwardly inclined leaf springs are mounted on the end of the probe body within the sleeve and are resiliently urged against the inner surface of the sleeve so that they are free to slide over the surface of the sleeve while separation of the sensor head from the probe body is limited by engagement of the springs with an inwardly projecting lip on the sleeve.

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.