64 into complete engagement to multiply the end load force of the swing arm 60 against the table 11 to release the latch and raise the swing arm 60 initial motor 62 in stroke rotates the latch lever 66 about pivot pin 67 thereby shifting the position of eccentrically located oversized wedge bore 69 in latch hook 64 relative to the wedge journal 68 which extends through the parallel bars of the swing arm 60 such relative shift between journal 68 and bore 69 releases the wedging force of hook 64 against the latch bar 65 continued motor 62 in stroke rotates the lever 66 and hook 64 assembly about the axis of wedge journal 68 to clear the hook 64 of the latch bar 65 thereby freeing the front end of swing arm 60 for rotation about and away from table 11 control panels 70a and 70b illustrated only by fig2 for clarity are series connected thereby requiring both of the operator 39 s hands simultaneously to engage a machine operation an operational sequence of the above described machine begins with the swing arm 60 and shear plate 40 both in their respective upper limit positions thereby positioning the shear knives 50a and 50b above the surface of table 11 both t bar clamps 29 and 35 are also opened to the up position shuttle carriage 20 is.