Abstract: An apparatus and method for improving the measurement of force variation in a tire (20) being tested on a tire uniformity machine. The apparatus includes a loadwheel assembly (500) including a rotatable loadwheel (510) connected to load sensors (530, 540) for detecting forces imposed on the loadwheel (510) by a tire (20) being tested. Vibration sensors (700, 702, 704) are associated with the loadwheel assembly (500) for detecting vibrations in the loadwheel (510) caused by forces other than the forces applied by the tire (20). Means is provided for subtracting the vibration induced forces from the tire (20) imposed forces in order to provide more precise tire uniformity data. The vibration sensors (700, 702, 704) which comprise accelerometers are used to determine vibration induced forces in the lateral and radial direction with respect to the loadwheel (510).

Abstract: Methods and apparatus for determining an angular location on a round object during a current operation in order to facilitate positioning the object for subsequent operation. At a first station, an angular location identifying feature is sensed, and an angle at which a predetermined desired angular location is located with respect to the feature is determined. At a second station, the feature is sensed, the object is indexed from the feature in an amount equal to the angle, and the object is marked at the relocated predetermined desired angular location. Another method eliminates the marking step at the second station, and the subsequent operation is performed instead. Apparatus comprises a first station means and a second station means. The first station means includes means for sensing an angular location identifying feature on the object and measurement means for determining an angle at which a predetermined desired angular location on the object is located with respect to the feature.

Abstract: Tires are measured for a parameter correlated to a tendency to contribute to steering pull when used on a vehicle. A group of the measured tires is then ranked into a successive series by ordering the parameter measurements of the tires in the group non-decreasingly or non-increasingly. A set of at least two tires of substantially consecutive rank are then selected for mounting on the same vehicle in order to reduce steering pull.

Abstract: Steering pull to which a vehicle is subjected due to tire non-uniformity is measured accurately even in the presence of wind. An anemometer mounted in proximity of and in positionally fixed relation to the vehicle measures the speed and direction of wind apparent to the vehicle. Those measurements are used by a computer to determine a wind correction quantity which is subtracted from the steering pull measured at the steering wheel.

Abstract: A tire uniformity inspection machine is calibrated by applying to at least one force measuring channel thereof a signal which simulates the application of a force of a magnitude greater than any force actually applied to the machine during calibration. That signal, which is preferably of a magnitude appropriate to simulate the largest forces encountered during actual tire testing, can be generated by connecting the channel, preferably at its input, to an energy source through an impedance. The response of the channel to the signal is measured and a calibration factor is determined based on that response. Such calibration factor accounts for the actual behavior of the channel more truely than prior art calibration techniques which relied solely upon the relatively small signal excitation conditions achievable by applying a relatively small actual force to the machine. Thus, the invention affords tire uniformity measurements of improved accuracy.

Abstract: The mass of a tire/wheel assembly is altered to apply a static imbalance to the assembly in a manner which reduces the overall tendency of the assembly to cause vibration in the plane perpendicular to its axis of rotation when in use. The applied imbalance, combined with any static imbalance initially inherent in the tire/wheel assembly, results in a desired net static imbalance oriented so as to induce a centrifugal force which opposes, and therefore tends to cancel, at least one component, such as the first order harmonic, of radial force variation characterizing the assembly. The magnitude of the net static imbalance is limited and is preferably selected to substantially equal the lesser of either: (a) a predetermined maximum limit, or (b) the amount of static imbalance required to generate at a designated highway speed a centrifugal force whose magnitude substantially equals that of the aforementioned radial force variation component.

Abstract: Tires are measured to determine the value of a parameter indicating a tendency of the tires to cause vibration in a given direction in tire/wheel assemblies. Each measured tire is assigned a tire rank designation in accordance with the order in which its measured value of the magnitude of that parameter falls in relation to the magnitudes of that parameter among a certain group of tires. Wheels are measured to determine the value of a second parameter indicating a tendency of the wheels to cause vibration in tire/wheel assemblies in that same given direction. Each wheel in a certain group of wheels is ranked in accordance with the order in which the magnitude of its second parameter falls in relation to the magnitudes of the second parameter among the other wheels in the group.

Abstract: An object is positioned in fixed relation to a measuring axis without regard to centering the object on the axis and at least one series of data samples correlated to the distance between the measuring axis and a series of points located at angularly spaced intervals on at least one surface feature of the object are generated and stored. To determine the center of a first surface feature, the corresponding series of samples is analyzed to identify samples therein corresponding to points lying on a maximum inscribed circle whose center corresponds to that of the surface feature. To measure a second surface feature of an object with reference to the center of a first surface feature thereof, a first signal and a second signal correlated to the distance between the measuring axis and points on the first surface feature and second surface feature, respectively are generated.

Abstract: A machine for measuring force variation or imbalance of tires particularly at high speeds. A rotating roadwheel is engaged by a tire mounted on a spindle. Force sensing means, such as load cells, are operably interposed between the tire spindle and a force sensor mount. To minimize the adverse effects of mechanical resonance of the machine on force measurement accuracy, the roadwheel and/or the force sensor mount are connected to ground through dampers which provide a damping ratio of at least about five percent and preferably higher. Where the force sensor mount is to be supported by such damping means, the invention further contemplates interposing a large mass between that damping means and the force sensor mount.

Abstract: A tire rim for a tire testing machine has a stepped contour providing multiple positions to accommodate tires of differing bead diameters. One or more filler rings are mountable on a bead seat to provide the proper contour for inflating a tire having the next smaller diameter bead seated on the adjacent bead seat.

Abstract: A tire testing machine having a rotatably but actuatably fixed upper rim, a rotatable lower rim assembly and a hydraulic cylinder for raising and lowering the lower rim to a desired position. The lower rim assembly has a resiliently-biased center pilot in the form of a cone that is engageable with a recess in the upper rim to center the lower rim with respect to the upper rim and to transmit rotational forces from the upper rim to the lower rim. The centering action of the pilot is assisted by a pair of mating spherical washers associated with the lower rim assembly.

Abstract: An apparatus and method for predicting fore-aft translations of tires. An inflated tire is rotated at a nominally constant angular velocity against a freely rotatable rigid loadwheel under a radial load. Changes in the instantaneous effective radius of the tire as it rolls give rise to fore/aft forces which tend to translate the tire alternately forward, toward the direction of travel and aft, toward the opposite direction. The tendency of the tire to so translate is predicted by measuring variations in effective radius or a parameter correlated thereto such as changes in the motion of the tread surface of the tire or the loadwheel relative to the angular speed of the tire.

Abstract: Apparatus and methods for use in measuring the uniformity of a body such as a tire, wheel or the like wherein a waveform related to the uniformity of the body is digitally sampled to acquire a series of data samples, each of which is correlated with a respective physical location on the body. According to a first aspect of the invention, a non-repetitive error component of the waveform is corrected for by sampling the same location on the body at two different times and determining the difference between the corresponding data samples. A part of the total difference is allocated to each of the data samples in the series according to a predetermined methematical function which at least approximately describes the non-repetitive component of the waveform. The part of the difference allocated to each sample is then subtracted from it to obtain a corrected series of data sample.

Abstract: A rim mount for a tire uniformity machine. The upper rim has bolts that cooperate with keyhole slots in an adaptor to mount the upper rim. The lower rim has keyhole slots that cooperate with bolts threaded into a lower chuck to mount the lower rim.

Abstract: An apparatus and method for imposing a desired average radial load force on a tire by calculating the current average force between the tire and a loadwheel based on the average radial force and radial distance between the tire and a loadwheel over the last previous complete revolution of the tire, the spring constant of the tire and the current radial distance between the tire and the loadwheel. The calculated average force value is applied as a feedback signal to the loadwheel position controller in order to achieve the desired average radial load. The spring constant of the tire may be determined from the change in force per unit distance as the tire is loaded or programmed as a constant to be applied for testing all tires of a given type.

Abstract: Apparatus for inflating tires to a test pressure. The apparatus includes a shop supply of air and a regulated supply of air. A valve system is used to connect the tire to the shop supply to seat the bead on the test rim; to exhaust the air from the tire to bring the pressure in the tire to approximately the test pressure; and to the regulated supply to bring the air in the tire to the preselected test level. The difference between the actual test pressure and the desired test pressure is measured and that difference is used to control the pressure regulator so as to correct the test pressure in the next succeeding tire.

Abstract: Method of inflating tires wherein the tires are inflated to a bead seat pressure and thereafter the pressure is reduced without deflating the tires through the valve.

Abstract: An arrangement for measuring the rolling resistance of tires. The arrangement includes a horizontal roadwheel and several horizontally rotatable tires which are urged against the roadwheel and rotated thereby. The tire spindle assembly is borne by a carriage which is movable toward and away from the roadwheel on a floating platform. The radial force with which the tire is urged against the roadwheel is offset by a linkage structure attached between the platform and the fixed base of the roadwheel assembly such that instantaneous rotation of the platform relative to the roadwheel base is about the axis of rotation of the roadwheel. The linkage structure includes a load cell for measuring the radial force. The arrangement further includes a load cell generally at the perimeter of the roadwheel which measures the tangential rolling resistance force of the tire.

Abstract: An analog compensation circuit for compensating for mechanical instrumentation resonance. The transfer function of the instrumentation resonance phenomenon is determined, and the compensation circuit is constructed to produce the inverse transfer function of the instrumentation resonance transfer function. The input of the compensation circuit is connected to the electrical instrumentation output signal. With the instrumentation resonance modeled as the equivalent of a second order filter, the compensation circuit includes sections for producing at a combined output a first intermediate signal representative of a constant term, a second intermediate signal representative of a first derivative term, and a third intermediate signal representative of a second derivative term.