suitable for realizing a slow and slight precooling of the filaments this leads in particular to a very uniform cross section of the yarn with that it is possible to adapt the air quantity to the heat treatment of the filaments it is possible to influence advantageously both precooling and the formation of the cooling stream the method of the invention permits production of hoy yarns which have physical properties that permit direct further processing thus properties are obtained that otherwise are ascribed only to fdy yarns typical elongation and tenacity values of fdy yarns are about 30 and gt 4 cn dtex in comparison therewith table 1 shows two polyester yarns that were produced by the method of the present invention in this process the variant of the method was applied as results from the arrangement of the spinning apparatus of fig2 the withdrawal speed was set to 7 500 m min to assist the advance of the filaments an air stream was generated in the constrictor that reached a velocity of about 2 500 m min despite the high withdrawal speeds tenacity values were obtained that were clearly higher than 4 cn dtex with yarn deniers of 55 dtex and 83 dtex the elongation was respectively 34 and 30 both yarns distinguished themselves by a very good modulus ratio the boiling shrinkage of 3 to 2 8 was satisfactory fig5 illustrates a diagram wherein the tenacity of a polyester yarn is plotted as a function of the withdrawal speed two curves are.