Device for pneumatically threading a yarn in a double twist spindle

A pneumatic yarn threading device for a double twist spindle having a hollow central shaft with a yarn brake therein, and having means operative when the shaft is pneumatically pressurized for introducing yarn through its bore past the brake, wherein the device comprises:

• (a) a shaft comprising axially aligned mutually-spaced tubular portions joined together by a central portion having an axial bore of diameter larger than the bores of said tubular portions, the tubular portions having opposed ends facing each other across the bore of the central portion, and the central portion having a transverse passage extending thereacross between the tubular portions;
• (b) a yarn brake comprising an elongated capsule in the bore of the central portion and having opposed ends which are disposed in a first axially aligned position to abut said opposed ends of the tubular portions and close their bores, and the capsule in a second displaced position being offset from axial alignment to expose the bores at said opposed ends to permit yarn to be passed therethrough;
• and
• (c) means for controlling the position of the capsule comprising piston means slidably mounted in said transverse passage and having an opening therethrough receiving said capsule, the opening being larger in diameter than the capsule;
• yieldable spring means urging the capsule and the piston means normally to occupy a first position wherein the capsule is axially aligned with and closes the bores of the tubular portions;
• and one side of the piston means being pneumatically coupled to the bore of the central portion and operative when the hollow shaft is pressurized to displace the piston means and move the capsule to said second displaced position, whereby yarn can pass through said bores and the opening of the piston means for threading the double twist spindle.