a core enveloper , for applying a web of paper , plastic or the like , to a new core , for example , on an automatic web winder , is adapted to provide for web severing and core wrapping in either of two directions of wrap . the enveloper arms including the enveloper roll , the rider roll , the cut - off knife and web transfer brush are mounted on a subframe comprising a beam which , in turn , is rotatably mounted on a support frame and is thus movable , by a drive motor , to present the core in either an &# 34 ; over &# 34 ; or an &# 34 ; under &# 34 ; position with respect to the enveloper . the axis of rotation of the beam intersects a centerline through the core so that the geometry of the enveloper , with respect to the core , remains unchanged in either of the operating positions of the enveloper .