According to fracture characteristics of rock caused a pick and its related data

breakage mechanisms and breaking effects of rocks influenced by different cutter spacing are analyzed. Cutting tests with different cutting depths and cutter spacing are performed using a rotary cutting machine with a single pick. The cutter spacing is optimized by three indicators

i.e. specific energy

coarseness index and cutting force

and the optimum ratio of cutter spacing to cutting depth for one type of sandstone is determined. Experimental results show that breaking process of the sandstone is divided into five phases

i.e. the generation of fine chips in a primary crushed zone

the formation of nucleus and its energy accumulation

the extension and connection of cracks

the falling of fracture and the regeneration of fine chips in a secondary crushed zone. The fracture is dominated by tensile failure and meanwhile accompanied by squeezing and shearing failure. Under the optimum cutting conditions

the higher coarseness index occurred when the rate of blocks is increased

and specific energy is lower. Through analyzing rock breaking process and the optimization of cutter spacing

it provides reference for breakage mechanism of rock by the roadheader and its pick arrangement.