Force measuring device

A device for measuring forces including:

• a ball or roller bearing having concentric inner and outer rings for accommodating at least first and second rows of rolling elements therebetween,
• first and second resistance strain gauges on said ball or roller bearing mounted at first (1) and second (3) measuring positions proximate said first row for sensing cyclic strains applied thereto,
• a third resistance strain gauge mounted on said ball or roller bearing at a third measuring position (2) proximate said second row for sensing cyclic strains applied thereto,
• said ball or roller bearing being adapted to absorb radial and axial forces applied thereto, said first, second and third strain gauges being adapted to change resistance and provide a signal in response to cyclic strains applied to said respective measuring positions,
• first (17) and second (18) and third (14) amplifiers coupled to the output of said first, second and third strain gauges, respectively,
• first (19), second (20) and third (16) rectifiers coupled to the outputs of said first, second and third amplifiers, respectively,
• a compensator (15) coupled between the output of said third amplifier (14) and the input of said third rectifier (16) for compensating for bearing ratio percentages, and the apparent axial force resulting therefrom, with only radial forces acting on said first and second rows of rolling elements,
• said compensator being adapted to reinforce the weaker signal of the signals proceeding from the first and third measuring positions, to which the radial forces are applied in the same direction, until said apparent axial force is eliminated, and
• a subtractor (22) for subtracting said compensated signal at the output of said third rectifier (16) from the signal at the output of said first rectifier (19) to provide a different signal U.sub.A corresponding to actual applied axial force.