Pulling unit

The pulling unit has one expanding sleeve with outer surface fitting the valve seat and inner surface fitting one conic spindle and cut into three equal parts connected through the springs in the slots, one small pressure plate mounted to one end of the expanding sleeve, one screw sleeve screwed to the stud of the conic spindle, one large pressure plate mounted on the surface of cylinder cover, and one nut with two welded handles mounted on the screw sleeve. After the expanding sleeve is mounted inside the conic spindle and inside the hole of the valve seat and the screw sleeve is turned to press the small pressure plate and make the outer surface of the expanding sleeve contact with the inner surface of the valve seat, the valve seat may be disassembled easily. The pulling unit is simple, convenient and reliable.