vertical bore 39 for the spring 20 this passage 39 is actually a hole with a sufficiently large diameter to prevent its walls from touching the spring during the pivoting action of the support 16 around the vertical axis of the stud 15 every flexible appliance 32 screwed on the end of the threaded bushing 30 is connected to a corner piece or member 41 by means of screws 66 engaged in the threaded nut 35 this corner piece 44 is provided with two projections or flaps 41 and 42 through which threaded rods 43 and 44 are fitted the threaded rods 43 and 44 as illustrated in fig2 are screwed through the fixed lengthwise beam 3 and secured in their position by means of nuts 45 and 46 the knurled knobs 47 and 48 are fitted on the threaded rod 43 or 44 in such a way as to enable the shifting of the corner piece 40 along a horizontal plane relative to the fixed member or beam 3 washers 49 and 50 are provided to provide a reliable contact between each of the flaps 41 or 42 and their respective knurled knobs 47 and 48 as illustrated in fig1 a conveyance device 51 is pivotably mounted on the beam 3 and is adjustable under pressure to form an inlet of the upper and lower straightening appliances.