is thus braked workpiece w reserves thus a counterclockwise aligning movement about pressure stamp 15 by cloth feed 7 which is enhanced in needle feed sewing machines by the needle during the rotation of main shaft by 180 u00b0 following the feeding phase of cloth feed 7 solenoid valve 25a is disconnected and assumes switching position a compressed air cylinder 14 is thus vented on the second side of working piston 18 over line 16 and connection a and r of solenoid valve 25a while the first side of working piston 18 is admitted with the compressed air supplied from the compressed air source over connections p and b of solenoid valve 25a and line 17 thus lifting pressure stamp 15 from workpiece w and relieving it of pressure as described above workpiece w which is pushed during its aligning movement with its edge against guide arm 10 can yield to the left with pressure stamp 15 lifted and pressure relieved respectively under the latter transverse to the direction of feed arrow v related to fig2 due to the intermittent movement of pressure stamp 15 adapted to the feeding phase of cloth feed 7 each aligning movement is followed by a yielding movement so that an exact contour correct control of arcs 42 to 45 is achieved by interrupting the beam of edge scanner 22 23 at the end of an arc relay 61 is disconnected contacts 54 and 56 of switch 55 are thus opened and solenoid valve 25a is disconnected it it held in switching position a by spring force.