The effect of grease level and backlash on the AH-64 intermediate gearbox using a unique test rig

Developing a diagnostic algorithm requires conducting experiments under working conditions as close as possible to the real life. In the case of the AH-64 Apache intermediate gearbox this task is difficult, because of the high power and rotation speed it requires. To enable the research in the laboratory, a closed loop belt-based device capable of producing the necessary torque and rotation speed was designed and built. Using the test rig, an examination of the vibrations signature of the gearbox was conducted which aimed to distinguish between fully lubricated and under lubricated transmissions, and between transmission with normal and excessive backlash. Gear under-lubrication caused an increase in the vibration level and temperature. Further research is needed to examine if the vibration level increase is due to lack of grease or high temperature. The backlash presented a change in vibrations that varied between the three axes which is probably due to the change in the pressure angle.