Sensing arrangement on a material roll

Abstract From the Canadian patent

Sensing arrangements on material rolls are used to give advance warning when the material web forming the roll approaches its end. Usually this involves the sensing of the reduction of the roll diameter with the help of a sensing device resting against the roll periphery. In the case of roll suspensions where the centre of the roll is not fixed, these sensing arrangements cannot be used. Here it is possible instead to use a sensing arrangement which comprises a field-generating element e.g. a permanent magnet, present in the centre of the roll together with a movable sensing device resting against the periphery of the roll, e.g. a heavy current switch which is acted upon at a certain …