Abstract: In order to solve the many faults and difficult maintenances of the imported shearers ranging booms, with the numerical simulation and site practices met hod, a design plan of a domestic easy maintenance and full straight gearing ranging arm was provided for 7 m high cutting height. A full gearing driving, a casting and W elding combined casing, real-time analysis forced lubrication, combined multiple cooling and other key technologies were applied to realize five grade direct gearing dri ving of the easy maintenance direct gearing ranging arm and to improve the stability of the gearing mechanism. During the 7 months application of the easy maintenanc e and full direct gearing ranging arm in Daliuta Mine, the failure rate was 20% lower than the imported ranging arm and the maintenance time was reduced by about 3 0%. The failure rate of the equipment and labor intensity of the miners were highly reduced and the coal mining efficiency and benefit were improved.