The shearer cutting section is used to adjust the upper bearing clearance of the heavy-duty planetary reducer. The heavy-duty planetary reducer includes an inner ring gear, a sun gear and a planet carrier, and a plurality of planetary gears and sun gears are mounted on the planet carrier. Engaging with a plurality of planet gears, the ring gear meshes with the planet gears, and a bearing housing is disposed on the cutting portion of the shearer and located at a lower portion of the planet carrier, and a tapered roller bearing 1 is disposed on the bearing housing, and the inner ring gear is provided The upper part is provided with a bearing seat 2, and the bearing seat 2 is provided with a tapered roller bearing 2. The adjustment method of the two gaps of the tapered roller bearing comprises the following steps: step one, installing a sealing cover; step two, calculating a sealing cover and a bearing seat The gap S is between the steps S; the adjustment amount X of the two gaps of the tapered roller bearing is calculated; and the sealing cover is improved according to the adjustment amount X. The effect of the gap adjustment method is good, which not only improves the service life of the bearing, but also improves the service life of the shearer.