A conductor for transmitting an electrical signal from a signal generator on a rotating member to a signal detector on a relatively stationary member across the motion interface between the two members comprises at least one solid carbon graphite ring mounted coaxially between the two members and having a first annular surface in intimate contact with a mating conductive surface on the signal generator and having a second annular surface in intimate contact with a mating conductive surface on the stationary member that is electrically connected to the signal detector, said carbon graphite ring functioning as an electrical interconnection between the two members.

A signal communicator for transmitting an electrical signal from one member rotating relative to another member is in the configuration of a journal bearing and comprises at least one conically shaped annular graphite ring supported by inner and outer electrically conductive races. While one race is insulatively mounted on the rotating member and electrically connected to a condition sensor, the other race is insulatively mounted on the relatively stationary member and electrically connected to a signal detector, and the graphite ring is an electrical conductor interconnecting the sensor and detector via the two races. Alternatively, two opposing and contacting graphite rings are mounted in nonconducting carriers, one of the carriers keyed for rotation with the sensor while the other is mounted on the relatively stationary member. Electrical connections are made directly from the sensor to one of the graphite rings and from the detector to the other of the graphite rings and the rings therefore function as the electrical interconnection between the rotating sensor and the relatively stationary detector.

A wheel rim displacement measuring apparatus which measures radial and axial displacements of a rim wall on the basis of a nut seat pitch circle. A wheel to be measured is mounted on a lower head on the basis of a hub hole center and rotated about an axis of the lower head. An upper spindle which is horizontally displaceable relative to the lower head is adjusted in position so as to align with a nut seat pitch circle center of the wheel and is rotated about the axis of the lower head. A Fourier analysis is carried on a wave of the displacements of the upper spindle so that an eccentricity amount of the nut seat pitch circle center from the hub hole center of the wheel can be calculated from the first harmonic. In a computer, a wave of the displacements of the rim wall measured on the basis of the hub hole center is amended in calculation to a wave of the displacements of the rim wall from a true circle having a center at the nut seat pitch circle using the first harmonic wave.

A wheel clamp for mounting a wheel aligning tool on a wheel rim and in a plane parallel to that of the wheel rim is disclosed. A lower bracket, a center sliding bracket and an upper clamping bracket are all mounted on a pair of parallel rods. The lower bracket is fixed to one end of the parallel rods, and two rim-engaging fingers project rearward therefrom. The upper clamping bracket slides freely on the parallel rods, and a single rim-engaging finger projects rearward therefrom. The upper sliding bracket may be positioned on the parallel rods so that the three rim-engaging fingers bear against either the inside surface or the outside surface of a peripheral lip found on the wheel rim. A clamping mechanism mounted on the upper clamping bracket fixes the upper bracket to the parallel rods and stresses the three-rim engaging fingers against either the outside or the inside surface of the peripheral lip, depending on which direction a knob on the clamping mechanism is turned. Alternative mounting means are provided on the center sliding bracket which allow the wheel clamp to be mounted directly on the lug bolts of a vehicle wheel.

An arrangement for mounting measuring devices of axle measurement equipment with a fastening plate that is adapted to be installed at the vehicle wheel aligned parallel to a flat reference surface of the vehicle axle by means of abutment pins extending through the wheel disk by way of through-openings. An incorrect alignment of the plane of the fastening plate which causes an incorrect adjustment of camber, toe-in or caster, is avoided with a completely satisfactory abutment of all abutment pins at the reference surface. Unevennesses of the reference surface or especially foreign bodies disposed between the contact surfaces of the abutment parts, such as, for example, metal shavings, will be recognized if a voltage is applied between the respective electrically conducting but mutually insulated abutment pins and the vehicle part carrying the reference surface, and if current, voltage or contact resistance is measured between the electrical connections by means of an electrical measuring device connected in the circuit.