arm 2 of pliers 1 induced by piston 3 causes the hooking of the aforementioned first capsule 13 with the related bobbin 14 to spout 17 of said arm once hooking has taken place piston 8 again causes runner 7 to move backwards up to the end of stroke pistons 4 4 39 extend until the mechanical pliers 1 is coaxially realigned with seat 15 of the sewing machine position a piston 8 causes runner 7 to move forward until the loaded bobbin 14 with the related capsule 13 is inserted in said seat piston 3 causes the backward rotation of the mobile arm 2 with ensuing unhooking from said bobbin and said capsule and lastly runner 7 is repositioned at the end of stroke together with pistons 4 4 39 which are lowered to a resting position position d while the sewing machine restarts it operation the loading cartridge 21 is substantially constituted by a horizontal external box shaped body 22 wherein a longitudinal pin 23 is comprised which forms the support for the loaded bobbins 14 with the relevant capsules 13 on the front a shaped stirrup 24 is provided which forms the bearing of said bobbin capsule assemblies and which performs the function of a guide for the engagement of the mobile pliers 1 in its turn the front part 25 of said pliers 1 is provided with guide elements 26 which shift with the configuration of said capsules this has the purpose of ensuring always and certainly the.