Reciprocal cam drive for sheet metal shears

Claim 1

IN METAL-SHEET SHEARS COMPRISING TWO SIDE COLUMNS INTERCONNECTED BY TUBULAR STRUTS, TWO BLADES COACTING FOR CARRYING OUT A HORIZONTAL CUT, AND TWO BEAMLIKE BLADE HOLDERS TO WHICH SAID BLADES ARE SECURED, THE LOWER HOLDER BEING RIGIDLY SECURED TO THE CORRESPONDING STRUT AND THE UPPER ONE BEING VERTICALLY GUIDED, THE IMPROVEMENT COMPRISING GUIDE PINS TO THE LOWER ENDS OF WHICH IS SECURED THE UPPER BLADE HOLDER, SAID GUIDE PINS BEING DISPOSED IN VERTICAL GUIDES BUILT IN THE UPPER STRUT AND BEING BEVELED AT THEIR UPPER ENDS TO ONE AND THE SAME SIDE, SLIDING WEDGES ADAPTED TO COACT WITH THE BEVELED FACES, A TIE ROD ON WHICH SAID WEDGES ARE IMMOVABLY MOUNTED, AND CONTROL MEANS IN OPERATIVE CONNECTION WITH SAID TIE ROD, THE LATTER IN THE COURSE OF ITS WORKING STROKE CAUSING SAID WEDGES THROUGH PRESSURE ON THE BEVELED SURFACES OF SAID GUIDE PINS TO DEPRESS THE UPPER BLADE HOLDER AND THE BLADE SECURED THERETO AGAINST THE ACTION OF TENSION SPRINGS FOR THE PURPOSE OF CARRYING OUT THE CUTTING OPERATION.