The linear movement of a flexible steel cable, which can have a length of up to 3 m, is converted into an rotary movement with the aid of a measuring drum.
The measuring drum is connected to the shaft of an encoder. In this way a change in displacement of the measuring cable causes the shaft of the encoder to rotate by a directly proportional amount which can be recorded. The restoring force of the spring drive holds the measuring cable tight at all times and prevents any sagging which would otherwise induce an error. The cable is wound up precisely and reproducibly wrap for wrap in the helical groove of the drum. The nozzle, through which the cable enters the drum, is protected with a brush and a bellow to prevent water or dust entering the drum.
