In a preferred embodiment of a device according to the invention, {HEAD ~ said positioning arm} comprises {TAIL ~ a double working cylinder} to perform the movement of the positioning arm 
comprises
In a preferred embodiment of a device according to the invention , { HEAD ~ said positioning arm } comprises { TAIL ~ a double working cylinder } to perform the movement of the positioning arm
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH