Principle of operation
The Clavis belt tension meter measures the natural frequency of vibration of a belt span. This frequency is directly related to the tension in the belt. As the tension in the belt is increased the frequency of vibration also increases. The belt is forced into vibration by gently tapping or plucking it. The vibration is usually not visible and also inaudible.
The relationship between the measured frequency and the tension of the belt should be determined from a calibration test on the belt span. A Clavis calibration rig is available for those users of this instrument who wish to perform their own calibrations, or we can undertake your calibration in our laboratory. Alternatively the relationship between belt tension (T) and frequency of vibration (f) may be calculated from knowing the mass per unit length of the belt (m), and the belt span (l), using the expression;
Where T is in Newtons, F in Hertz, I in metres, and m in Kg/metre. However as the belt does have some flexural stiffness the predicted tension for a given frequency will be slightly greater than the actual tension. This is most noticeable on short belt spans where the belt bending stiffness is the greatest. For belt spans greater than 250mm a calculation based on the above expression will provide results within 10% of the actual values.
