Device for displaying surface smoothness (black ice) on roads for motor vehicles

摘要

A sensor wheel which is permanently braked by an adjustable braking force is continuously pressed against the roadway during driving. In the event of the road becoming slippery, the sensor wheel remains stationary and is retrorotated a little counter to the direction of travel, resulting in the tripping of a black ice alarm on the dashboard. In order for the sensor wheel to be able to compensate unevennesses of the ground by an adequate spring excursion, it is mounted on a relatively long arm which moves about a pivot. This pivot is fixed between the front and rear wheels under the vehicle floor, in the tyre track. Since the relatively small sensor wheel cannot overcome larger obstacles (e.g. kerbstones) when driven backwards, the arm on which it is mounted buckles, as a result of which the part below the buckle now slides over the obstacle. When forward travel is resumed, the arm is restraightened by a spring. This device can remain mounted on the motor vehicle all year round. The sensor wheel is folded onto the roadway when required.