Weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum

A weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum (D), wherein said drum (D) is formed of several fixed sectors (5), each provided with respective support shanks (5g) housed in respective seats formed in a static support disk (6), coaxial to a drive shaft (A) of the weft feeder, and wherein the spacing of said spaced coils on the drum (D) is caused by oscillatory and tilting movement of several moving sectors (7), each provided with respective support shanks (7g) housed in respective seats formed in a tilting support disk (8), eccentric and skew with respect to said drive shaft (A) of the weft feeder, and wherein elastic elements which exert a compressive force on said shanks (5g, 7g) are provided, to keep said fixed sectors (5) and said moving sectors (7) in a position of stable engagement within their respective seats, wherein the fixed sectors (5) and the moving sectors (7) are each provided with a single support shank (5g, 7g) having a general shape of a trapezoidal right prism, housed in a respective seat consisting of a cavity having a congruent trapezoidal shape, at least to a limited extent of its converging side walls, and wherein said elastic elements exert a compressive force on the major base of said support shank having a general shape of a trapezoidal right prism.