AGMA 09FTM18-2009 pdf free.AGMA Technical Paper Does the Type of Gear Action Affect the Appearance of Micropitting and Gear Life? by A. Williston, A&J Engineering.
A surface fatigue failure mode was desired during testing. Proper selection of the applied torque was necessary to promote a contact fatigue failure on the gearing. If the applied load is too high, tooth breakage may result — potentially damaging the tested component as well as the test equipment. If the load is too low, the time-to-failure of the test will be prohibitive. It was necessary to find a balance between these extremes.
It was also important to constrain as many variables not related to the gearing geometry as possible. These constraints included, in part: gearing material, heat treatment, applied torque, and lubrication. Of key importance is the lubrication. A high test load dictated that an assured supply of cool oil be available to the bearings and gears. Also, any cross-contamination must be prevented. Therefore, each gearbox was supported by its own oil reservoir, pump, filter, and heat exchanger.
Instrumentation for both gearboxes was similar and included: bearing temperatures, lubricant temperatures at various points, lubricant cleanliness and vibrations in three axes. Additional signals tracked circulated torque, motor amperage and speed.
3-hole gearbox
The concept for the 3-hole gearbox was to build a much simpler and less expensive test gearbox that would allow gearing to be optimized for the applied test loads. However, by reducing the size of the gearing (specifically center distance) connecting the test gearboxes proved to be troublesome. Couplings, torque actuators, and torque transducers sufficient to carry the test load were too large to fit when only one gearset was used. By expanding the scope to two gearsets with the same ratio, the original 4.0” center distance was increased to 8.0”.
As shown in figure 3, the concept has a pinion driving one of two identical gears on an intermediate shaft, while the other gear on the intermediate shaft drives another pinion. With the pinions having the same number of teeth, the ultimate ratio is 1:1. Thus exact tooth counts between the two test gearboxes are not necessary, and various gearing designs can be compared and optimized without limitations.AGMA 09FTM18 pdf download.