Self-threading yarn brake mechanism in a hollow spindle assembly of a textile yarn processing machine

In a textile yarn processing machine, such as a two-for-one twister and the like, having spindle assemblies for the processing of yarn and each including a carrier mechanism for carrying a package of yarn to be withdrawn and processed and defining an elongate passageway therethrough for the yarn withdrawn from the package, an enlarged cavity forming a part of and enlarging said passageway at said cavity, and pneumatic means for threading yarn through said passageway for start-up of said spindle assembly prior to yarn processing;

• the combination therewith of an improved yarn brake mechanism positioned in said cavity for applying a desired tension to the yarn passing therethrough and being characterized by a self-threading construction, said yarn brake mechanism comprising:
• a stationary braking member in the upper portion of said cavity and forming a generally flat, inclined braking surface generally around said passageway at the entrance to said cavity;
• a movable, ferromagnetic, braking plate pivotally mounted within said cavity for cooperation with said stationary braking surface and for generally covering said passageway at the entrance to said cavity;
• magnet means adjustably mounted in magnetically attracting proximity to said ferromagnetic braking plate for movement closer to and away from said braking plate for adjustably biasing said braking plate toward said inclined braking surface for applying a desired tension to yarn passing therebetween during processing;
• a yarn bypass channel formed in said stationary braking member and leading from said passageway at the entrance to said cavity and laterally alongside said stationary braking surface for receiving the yarn during pneumatic threading of the yarn through said passageway for start-up of said spindle assembly prior to yarn processing and eliminating the passage of the yarn between said braking surface and braking plate during pneumatic threading;
• and
• an obliquely extending, deflection surface formed in said stationary braking member between said bypass channel and said inclined braking surface for deflecting the yarn from said bypass channel into position between said braking surface and braking plate after pneumatic threading of the yarn and upon additional tension being placed upon the yarn during start-up of said spindle assembly.