Experimental Evaluation of Face Gears for Aerospace Drive System Applications.

Abstract : The experimental evaluation of face gears has been ongoing at NASA Lewis since 1991. Testing to date has focused on the feasibility of using this gear mesh to transfer power between intersecting shafts as found in helicopter main rotor transmissions. The focus of the experiments has been to deternaine the failure modes and load capacity of this gear mesh operated in a simulated helicopter transmission environment. At this time tests have been completed on a total of ten sets of face gears using a test facility located at NASA Lewis. Surface pitting was the predominant failure mode generated, however bending failures were also experienced. All tooth fractures due to pitting or bending occurred on the gear member. The spur gear pinion typically only had minor wear. Results from these tests indicated that the components would have to use aerospace gear materials and advanced manufacturing procedures to achieve the desired long component life.