... , DBYK is two-stage hard-toothed surface taper cylindrical gears hollow shaft type reducer, 3 and DCY for three-level hard-toothed ... , DCYK for three-level hard-toothed surface taper cylindrical gears hollow shaft type reducer, 5, DFY into four categories of hard-toothed ... -toothed surface taper spur gear reducer. Working conditions: 1, input shaft highest RPM is not more than 1500r/min. 2, gear ...