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The transmission rig is a four-square con.guration which recirculates the power via a return loop that adds the power back to the input via differential. A detailed descrip-tion of this rig can be found in (Ref. 28). Tachometers were used on both the input and output shafts. The output tachometer signal is 1.) used to parti-tion the measured data into individual carrier cycles and 2.) count the number of output shaft cycles to produce a reset pulse to indicate when the planetary geometry has returned to its initial orientation. The planetary system has a repeat cycle of 105 output shaft cycles. Accelerometer Placement The accelerometers are Endevco 7259A-10 with a band-width of 50khz. Accelerometer A1 was mounted to the in-put end of the transmission just above the pinion. The in-put spiral bevel pinion has a thrust load against its tri-plex ball bearing and single roller bearing. This is the direc-tion of Accelerometer 1’s sensitivity axis and is aligned to the rotational axis of the input shaft. (Ref. 29) Accelerom-eter A2 is positioned 15 degrees counter-clockwise from A1 and mounted on the side of the transmission housing. Ac-celerometers A3 and A5 are mounted to a special bracket. This is the same bracket, and bracket location, used in .ight tests (Ref. 30) These two accelerometers are located 180 degrees apart. Accelerometer A4, like A2, is mounted to the side of the transmission housing. All accelerometers have their sensitivity axis in the transmission’s radial direction. It was found from previous tri-axial accelerometer tests that this direction provided the best results. (Ref. 31) All .ve ac-celerometers were conditioned using an Isotron 2972B con-ditioner. From previous tests, A1 had the spiral bevel as the dominant components (Ref. 28). In this work, Accelerom-eter A3, produced the highest levels of vibration where the dominant features were attributed to the spiral bevel pinion and planetary mesh. Accelerometers A4 and A5 also had signi.cant spiral bevel mesh components. 直升机网 www.helicopter.cn 直升机翻译 www.aviation.cn 本文链接地址：Sun Gear Fault Detection on an OH-58C Helicopter Transmission(25) |
