Yarn feeding Device Having a Brake Opening Device for Threading

In a yarn feeding device comprising a storage drum for a yarn and an output brake which is arranged at a withdrawal end of the storage drum, said output brake comprising a storage drum counter-brake surface which is coaxial to the storage drum axis and is continuous in a circumferential direction and a brake element held on said counter-brake surface under a spring action wherein said spring action acts axially and counter to a yarn withdrawal direction, said brake element having a brake surface which is also continuous in the circumferential direction and coaxial to said storage drum axis, said yarn feeding device further comprising a mounting for said brake element, which said mounting is separated from said storage drum, and a pneumatically operable brake opening device which comprises a pressure chamber having a pneumatically loadable, axially movable boundary wall, comprising the improvement wherein said boundary wall is connected in motion-transmitting fashion to said brake element such that movement of said boundary wall effects movement of said brake element at least in a direction of movement against said spring action, said output brake including a pressure supply arrangement which pressurizes said pressure chamber with an elevated pressure or a vacuum such that said boundary wall moves in said direction of movement, said brake element being axially movable into a threading position when said boundary wall is pressurized by the elevated pressure or the vacuum such that said brake surface is lifted from said counter-brake surface to permit threading of the yarn therebetween.