Abstract: The yarn feeding device for a yarn-consuming textile machine includes a mechanism for positively feeding yarn to a textile machine according to predetermined yarn consuming speed changes and timings of those changes, this mechanism having a rotary yarn feeding element (1,83) carrying a main yarn reserve (84), a motor (82) for rotating the yarn feeding element (1,83) at a motor rotation speed according to the variable yarn consuming speed and a motor controller (51, 57) for controlling the motor; a yarn reserve device (3,78; 20, 77) for building up or reducing an auxiliary yarn reserve consisting of a portion of yarn extending between the main yarn reserve and the textile machine, when changes in the yarn consuming speed occur that are so rapid that the motor (82) temporarily cannot change the motor rotation speed to deliver yarn from the rotary yarn feeding element at the yarn consuming speed because of motor inertia; a controller for the yarn reserve device (3,78; 20,77) which increases or decreases the auxi