Yarn brake mechanism

In a spindle assembly of a textile yarn processing machine, especially a two-for-one twister, having a hollow spindle defining an axial yarn passageway extending therethrough and including pneumatic threading mechanisms for selectively creating a pneumatic flow in a predetermined direction through said yarn passageway to automatically thread a yarn therethrough during a thread-up operation;

• the combination therewith of an improved yarn brake for applying tension to a moving yarn passing through said yarn passageway during normal operation and to facilitate pneumatic threading of the yarn through sad passageway during a threading-up operation, said yarn brake comprising
• a braking body movably positioned within said passageway of said spindle and being of predetermined dimensions allowing the passage of the yarn through said passageway and having upper and lower braking surfaces thereon;
• a stationary member positioned in said passageway of said spindle above said braking body and having a vertically-extending aperture therethrough and a downwardly-facing braking surface around said aperture for passage of the yarn therethrough and for cooperating and being engageable with said upper braking surface of said braking body;
• a movable member positioned for longitudinal axial movement in said passageway of said spindle below said braking body and having a vertically-extending aperture therethrough and an upwardly-facing braking surface around said aperture for passage of the yarn therethrough and for cooperating and being engageable with said lower braking surface of said braking body;
• spring means operatively associated with said movable member for biasing said movable member upwardly toward said stationary member and into a position in which said braking surfaces of said braking body are in braking engagement with said braking surfaces of said stationary and movable members to apply tension to the yarn, said spring biasing means applying a force in opposition to and less than the force of the pneumatic flow created by said pneumatic threading mechanisms for allowing downward movement of said movable member under the influence of the pneumatic flow selectively created by said pneumatic threading mechanisms for separation of said braking body from said stationary and movable members for threading of yarn through said yarn brake;
• and
• intercepting means mounted in said passageway of said spindle and being constructed and positioned for receiving and holding said braking body, upon downward movement of said movable member during yarn threading, in a position in which said braking surfaces of said braking body and said stationary and movable members are out of engagement, but remain substantially aligned, for easily returning to braking engagement after the yarn threading and upon upward movement of said movable member.