zone where the central module 11 and the base module 13 are joined together with reference now mainly to fig2 and 3 which show in detail the parts arranged inside the modules 13 and 11 it can be seen that the main shaft 10 extends from a pulley handwheel group 22 which can be driven by a motor fig3 and has first of all a pulley 9a for transmitting the movement to the upper shaft 17 the main shaft 10 also operates an eccentric 23 enclosed by a connecting rod 24 fig1 which extends downwards and is operationally connected to an extension 25 from which a spindle 26 extends in a direction transverse to the main shaft 10 the latter forms part of the abovementioned second kinematic assembly 21 ending in the hook operating rod 20 the main shaft 10 then continues and is connected to a second eccentric 27 operating an arm 28 which in turn is connected to a shackle 29 keyed on to the side shaft 18 this forms the said first kinematic assembly connecting the main shaft 10 and the side shaft 18 the sections of the main shaft 10 side shaft 18 and hook operating rod 20 end on an edge 11a of the central module 11 in joining components forming substantially axial coupling devices shown in detail in fig2 this shows a rapid engagement coupling 30 comprising a collar 31 fig5 and 6 with axial receiving holes 32 arranged diametrically at a distance from each other and drive pins 33 fig4 which can be inserted in the receiving holes 32 in an original.