the worktable position d of fig1 and fig4 at this point the jack 21 is activated and by means of the pusher plate 25 acts on the edge of the overturned mattress so as to move the mattress 5 transversely on the worktable 4 and move it closer to the sewing machine so that the assigned operator can perform hemming of the opposite face of the mattress fig5 it is noted that since in the position d the tube 19 is arranged below the mattress fig1 the jack 17 is also activated simultaneously with the jack 21 so that by returning the tube 19 onto the cylinder of the jack 17 the mattress 5 can rest completely on the worktable 4 and allow a regular movement and exact positioning of the mattress with respect to the sewing machine on the part of the operator and the execution of perfect hemming finally while final hemming proceeds the arm 10 is inverted again in the initial position b of fig1 in order to be ready to proceed with the overturning of subsequent mattresses as can be seen the described device achieves the intended aim and objects in particular it allows to overturn mattresses even when the worktable is constituted by a roller bed the described device is susceptible of numerous modifications and variations all of which are within the scope of the appended claims in particular in order to ensure better grip of the mattress on the tube 19 during overturning said tube is provided with a surface covering of friction material another improvement consists in using on the bracket 16 means which are adapted to form with the tube 19 a sort.