Device for braking the yarn unwinding from a disc bobbin

Claim 1

In combination, a bobbin having a cylindrical surface adapted for winding of a continuous strand thereon, the bobbin comprising first and second discs formed on the respective ends of the bobbin, the first disc defining a first continuous uninterrupted annular surface, the first annular surface lying in a plane normal to the axis of the cylindrical surface and being coaxial with the cylindrical surface, the first and the second discs both being of greater diameter than the cylindrical surface and the first disc being of greater diameter than the second disc, and a bobbin holder for supporting the bobbin for rotation of the bobbin about the axis of the cylindrical surface, the bobbin holder comprising means defining a cylindrically walled recess of greater diameter than the second disc and of smaller diameter than the first disc, the bobbin being received in the recess with the first annular surface portion of the first disc overlying a second annular surface defined by an annular portion of the surface of the bobbin holder around the mouth of the recess, the bobbin holder further comprising a pivot pin coaxial with the cylindrical wall and the bobbin, the bobbin being provided with a bore coaxial with the cylindrical surface for receiving the pivot pin, the pivot pin being provided with an axial bore, the bobbin holder further comprising a bolt having a shank and a head, the shank being provided with a recess and being received in the bore of the pin and the head being of larger diameter than the bore of the bobbin and resting on the outer face of the first disc, a torsion spring fixed to the bobbin holder and arranged to engage in the recess in the shank and urge the head against said outer face, whereby the first and the second annular surfaces are biased toward each other so that the continuous strand when guided between the first and the second annular surfaces is clamped therebetween with a force that holds the strand and the bobbin stationary when the strand is not tensioned fRom a point outside the bobbin, that permits the bobbin to rotate when the strand is tensioned from a point outside the bobbin and that brakes the bobbin to a halt when the tensioning is discontinued.