provided in parallel with each other between the upper and lower flanges 119a for the base frame in the upper and lower positions of the two shafts 120 a total of four claw plates 121 with the tips turned inward are installed in such a way as to permit their respective free rotational motion the pair of claw plates 121 at the upper level and the pair of claw plates at the lower level are respectively connected with each other by means of link mechanisms for their interlocking operation forming two pairs of grasping claws 122 namely upper and lower pairs the forward end of the working shaft 118 is connected in such a way as to permit their free rotational motion with the link mechanisms 123 connecting the two shafts 120 as explained above the various apparatuses are constructed in such a way that when the cylinder cy14 is placed into its operation the slide pipe 115 performs its sliding movement forward and backward along the guide 114 while they also are rotated and haft 118 slides in relation to the slide pipe 115 actuating the two pairs of grasping claws 122 simultaneously by way of the shafts 120 and the link mechanism 123 so as to perform their opening and closing operations.