Abstract: A road vehicle has a transducer which provides an output signal representing movement of an axle relative to a chassis of the vehicle. The output signal is compared with a reference signal to produce an indicator signal which is applied to means for indicating the axle load numerically and for providing a visual indication when the maximum prescribed axle load is exceeded. For initial calibration, the reference signal is temporarily substituted for the output signal and the numerical display is adjusted to display in selected units the prescribed maximum load. The output signal is then restored and the vehicle is loaded to subject the axle to the prescribed maximum load. While this load is maintained, the reference signal is varied until the numerical indication of the prescribed maximum load is restored.