A New Experimental Approach to Test Open Gears for Winch Drums

In several applications like hoisting equipment, cranes, open gears are used to transmit power at rather low speeds (tangential velocity < 1m/s) with lubrication by grease. In consequence those applications have particularities in term of lubricating conditions and friction involved, pairing of material between pinion and gear wheel, lubricant supply, loading cycles and behaviour of materials with significant contact pressure due to lower number of cycles.The comparison of proofed old rating methods (HENRIOT….) with ISO 6336 has shown that ISO is very conservative for through hardened steels gear wheels running with case hardened pinion specifically in the range of limited life.This has emphasis the need to develop experimental tests, in representative conditions. In order to assess new values of allowable contact-pressure stress numbers, the authors present the concept and the realization of a new test bench in order to satisfy those requirements with the associated procedures of calibration and testing.Analysis of experimental results and metallurgical analysis of cold working of tooth flanks are given. Fatigue result test are then compared to ISO and AGMA gear ratting method predictions.