an actuator body forming a first chamber and a second chamber with orthogonal planes, said first chamber being tangent to said second chamber;

a pneumatic piston subject to alternating movements, said piston being located in said actuator body;

a turning pinion having a base flange and an item holder disk head, said second chamber receiving said turning pinion such that said turning pinion is supported and housed in said second chamber, said piston having a toothed rack engaging with the pinion such that said pinion rotates with the item holder disk head in response to the alternating movements of the piston, wherein said pinion has a toothing formed of parallel pins, said parallel pins extending between said base flange and said item holder disk head, said flange and said item holder disk head being composed of a first material, said pins being composed of a second material, said second material having a mechanical strength that is greater than a mechanical strength of said first material, said base flange having an axial through bore and an integral neck for receiving a first support bearing, said item holder disk head having an axial shank and a neck for receiving a second support bearing, said axial through bore of the base flange receiving one end of said axial shank, said neck of said base flange having a base flange neck side, said neck of said item holder disk head having an item holder disk head neck side, said base flange neck side being disposed opposite said item holder disk head neck side, said base flange neck side and said item holder disk head neck side having bores following a circumference for receiving and holding the ends of said pins forming the toothing of the pinion.