Experimental Testing of Prototype Face Gears for Helicopter Transmissions

Abstract

An experimental programme to test the feasibility of using face gears in a high-speed and high-power environment was conducted. Four face gear sets were tested, two sets at a time, in a closed-loop test stand at pinion rotational speeds to 19 100 r/min and to 271 kW (364 b.h.p.). The test gear sets were one-half scale of the helicopter design gear set. Testing the gears at one-eighth power, the test gear set had slightly increased bending and compressive stresses when compared to the full-scale design. The tests were performed in the NASA Lewis spiral bevel gear test facility. All four sets of gears successfully ran at 100 per cent of design torque and speed for 30 million pinion cycles, and two sets successfully ran at 200 per cent of torque for an additional 30 million pinion cycles. The results, although limited, demonstrated the feasibility of using face gears for high-speed, high-load applications.