Boston Gear Corporation 872B-50K Speed Reducer

Boston Gear's 872B-50K inline helical gear reducer, part of the 800 Series, provides a 50:1 nominal reduction in an inline drive configuration designed for mounting along a motor shaft. The unit is a two‑stage helical gear drive in case size 7, with non‑flanged (M1) and flange‑mounted variants available within the 872B‑50K family, such as 872B‑50K‑M1 and 872BF‑50K‑M8. Some retailer listings show a 47.28:1 figure for this model, and the product is listed as discontinued in at least one catalog. Catalog pages reference part numbers like F872B‑50K‑B9‑M1 and F872BF‑50K‑B9‑M8, indicating multiple mounting and motor‑fit variants within the 872B‑50K family. In operation, it functions as a speed reducer to lower motor speed while increasing output torque for drive systems used in industrial equipment.