| abstract |
Disclosed is a crushing equipment for crushing a pillar or beam of concrete structures through opening and closing movement of a pair of arms while clamping the pillar or beam by a pair of crushing blades provided on the ends of the arms. A hydraulic cylinder 1 for opening and closing the arms comprises a second cylinder including a couple of cylinders 3' and 3", and a pair of first cylinders fitted into the cylinders 3' and 3", respectively, and each having a cylinder bottom serving as a piston 9. When a hydraulic oil is introduced through a fifth oil port 18 provided in the second cylinder on the side of the cylinder bottom, the first cylinders 2 are forwardly displaced. When the first cylinders 2 reach their stroke ends, pistons of the first cylinders are forwardly moved to close the arms for crushing the concrete structure. When the hydraulic oil is introduced through fourth oil ports 16, the pistons 5 are retracted by way of second oil ports 10 and oil passages 11. When the pistons 5 reach their stroke ends, the pressure of the hydraulic oil acts on the cylinder bottoms of the first cylinders by way of gaps retracting the first cylinders to open the arms. The hydraulic oil is into the hydraulic cylinder 1 supplied only through the fourth oil ports 16 and the fifth oil port 18, thereby simplifying control operation. |