in fig4 wherein a clamping means 90 is shown mounted on the bracket 48a and arranged on the frame 22 in a manner similar to the second clamping means 32 having a clamping arm 92 pivotable about an axis 94 attached to a tab 96 on a support frame 98 and a clamping bar 100 of 34 l 34 shape in cross section is mounted on a bracket 102 attached to the clamping arm 92 which clamping bar 100 has a pressure plate 104 directed inwardly towards the clamping arm 92 or the pressurized cylinders 60 a holding mechanism 120 is shown in fig5 wherein the reciprocable biasing means 60 is partially shown with a piston 124 attached to the piston rod 66 and a ratchet 126 is attached to the other side of the piston 124 and extends through the cylinder 62 a pawl 130 is swingably arranged about an axis 133 and is attached to an actuation cylinder 132 secured to the cylinder 62 to provide a dimensional holding arrangement for the reciprocable biasing means 60 in operation of the sewing machine a piece or pieces of web like material 34 m 34 to be stitched shown in fig1 is placed by a machine operator in a recess 110 on each bracket 48 and 48a beneath each clamping bar 46 a switch not shown is then activated by the operator to cause pressurized fluid to be distributed to the piston and cylinder mechanisms 30 of the first and second clamping means 26 and.