Patent ID: 7147030

Claim:
An operation group incorporated with a winding roll for automatically rolling up at least one curtain, the operation group comprising: a shaft insertable into and fixable within the winding roll; a hub ( 9 ) connected to an end of said winding roll; first elastic means ( 2 ) situated within the winding roll for automatically winding up the curtain on the roll, the first elastic means having a first end linked to said shaft ( 8 ) and a second end fixed to said winding roll; and, a mechanism ( 1 ) for imposing and stabilizing a pre-loading condition for said first elastic means ( 2 ), the mechanism located within said winding roll ( 3 ), said mechanism having: a sleeve ( 4 ) introduced into said winding roll and coaxially fixable to a first end ( 3 a ) of said winding roll; a barrel ( 5 ) having an axial hole, keyed slidingly on said shaft and axially movable within the sleeve between a first position and a second position (P 1 , P 2 ); a prismatic shank ( 50 ), provided at an end of said barrel for coupling with a complementary seat ( 10 a ), located in support means ( 10 ) for said winding roll; and, clutch means ( 7 ) situated between the sleeve ( 4 ) and the barrel ( 5 ), the clutch means mutually engaging said barrel and said sleeve when said barrel ( 5 ) is in the first position (P 1 ) and disengaging said barrel ( 5 ) from said sleeve when in the second position (P 2 ); second elastic means ( 6 ), disposed between said barrel and said sleeve for biasing said barrel so as to keep the barrel in said first position (P 1 ); said clutch means including a plurality of recesses ( 70 ) regularly spaced apart and provided in said sleeve, said barrel 5 having a disk ( 51 ) having complementary claws ( 71 ) facing said recesses and engagable therewith.