Shanghai Branch，Tiandi Science and Technology Corporation，Shanghai ，China

In response of the market′s urgent need for high-efficiency mining of the thinner coal seams and the lack of suitable shearer models at home and abroad，a MG2X250/1200-WD high-power shearer for the thinner coal seam was developed，and the key technical difficulties of shearer were mainly studied.By adopting temperature field analysis and structural optimization，the cooling water path of the rocking arm was arranged reasonably，which solved the problem of high temperature rise of high power density gear transmission system.Through the simulation analysis and structural optimization of the planet carrier，the key components of the rocking arm planetary mechanism，the maximum stress of planet carrier was reduced by more than 20%，and the reliability was greatly improved.The multi-body dynamics software ADAMS was used to simulate and analyze the meshing parameters of the walking wheel and the pin gear，and then the tooth profile was optimized.At the same time，the depth of carbon layer was increased by strictly controlling the process parameters such as temperature，time and gas phase carbon potential，which increased the contact fatigue strength of the walking wheel.The structure of the sliding shoe was optimized by solution and analysis of guide shoe，and the wear tests of 7 different wear-resistant materials were carried out to find the optimal wear-resistant materials.Through the above research，the key technical difficulties in the development process of the high-power and high-efficiency shearer for the thinner coal seam have been effectively solved，and the reliability of the coal-pulverized coal-cutting machine has been greatly improved.The MG2X250/1200-WD shearer developed has a installed power of 1 200 kW with the minimum surface height of 890 mm.It is the largest at home and abroad and has the ability to efficiently mine thin coal seams.

中国煤炭科工集团有限公司科技创新创业资金专项重点资助项目（2018ZD003）；天地科技股份有限公司科技创新创业资金专项重点资助项目（2018-TD-ZD008）