Abstract: Apparatus for producing bulked multifilament yarn incorporates a high pressure fluid passage debouching into an intermediate pressure expansion chamber. The high pressure fluid passage is formed with entries for yarn and high pressure fluid and the intermediate expansion chamber is formed with a yarn-deflecting surface and yarn-discharge passage both located across the chamber from the point where the high pressure fluid passage enters the chamber.

Abstract: Bulked and crimped yarn is produced by a device comprising yarn feed means arranged to form a yarn package, means for taking off yarn from an end of the package and heat exchanging means arranged to be in heat-exchanging relation with the yarn on its way to the package. Means capable of sensing the position of the take-off end of the package is arranged to send a control signal controlling operation of the heat exchanging means. The yarn feed means may be a fluid jet or feed nip rollers. A stuffer tube or a movable surface may be provided to receive the yarn package. The take-off position sensing means may be optical, electrical, acoustical, pneumatic, or mechanical.