Drum hydraulic shear is a widely used hydraulic shear. It is installed on continuous rolling mill or cross cutting mill for shearing steel plate or small section steel with thickness less than 12 mm. When the hydraulic shearing machine is used as the cutting head hydraulic shearing machine, its shearing thickness can reach 45 mm. The blade of the drum hydraulic shearing machine moves in a simple circle, so it can shear the rolling piece with a moving speed of more than 15m/s. Figure 9-1 (page P300) is a schematic diagram of the structure of the drum hydraulic shear. Ten thousand pieces 1 are mounted on drum 2 (Fig. 9-1). When the drum 2 rotates, the blade 1 moves in a circle. The drum type hydraulic shearing machine used for cutting head and tail is usually equipped with two blades on the drum, which are used for cutting head and tail respectively. Hydraulic shearing machine adopts start-up working system. The drum type hydraulic shearing machine used for cutting and sizing is generally of continuous working system. Because of the small width of the rolled piece, the drum hydraulic shearing machine in small workshop usually installs the blade on the lever which acts as the circumferential motion (fig. 9-2) (page P301). The hydraulic shears shown in Figure 9-2 (page P301) are also called rotary hydraulic shears. When the upper and lower blades cut into the rolled piece, they are not parallel in the vertical direction, and the head of the rolled piece is not even after shearing. Therefore, it is appropriate to shear round steel or corresponding billet with diameter less than 30 mm, as well as thin strip.