Patent attributes
A friction device (10), applied to roll-up curtains and the like, includes a tubular roller (1), on which the curtain (2) rolls up, and which is rotatably carried on a horizontal axis. The friction device (10) includes a threaded shaft (9), situated axially inside the roller (1) and connected to the roller (1) by interposition of an angular speed reducer group (4). A body (11), mounted sliding axially inside the roller (1), is screw-coupled with the threaded shaft (9), so as to translate axially due to the shaft (9) rotation during unrolling or rolling up of the curtain (2) on the roller (1). One or more elastic members (12), subjected to pressure or counter-thrust, are compressed, on opposite ends, between abutment means (13) and a surface of the body (11), to determine a friction effect, which varies as a function of the rotation direction of the roller (1).