A cutting/crushing device for the demolition of buildings has a pair of jaws (1) that pivot on frame (2). The jaws (1) are constrained to pivot in synchrony because each jaw (1) remains engaged with a guide pin (12) which substantially prevents relative movement of the two jaws (1). The guide pin (12) is guided by a slot (13) in the frame (2), aligned with a plane of symmetry between the two jaws (1), to prevent it from moving toward or away from either jaw (1). By guiding the guide pin (12) in this way, frictional binding and wear of the guide pin (12) are minimized. In addition, the shape of the recesses (11) into which the guide pin (12) fits can have smaller tolerances reducing play between the two jaws (1). Stoppers on the frame press against the rotatable jaws when they are fully opened to prevent any play.