In the aerospace industry, higher performance specifications are driving gear manufacturers to utilize revolutionary materials, such as AMS 6308 and Pyrowear 675, among others.  In the ground vehicle industry, where cost reduction is the driver, powder metal steel alloys are being seriously considered.  In all these efforts the ability of the gear to withstand impact loading is of significant interest. In order to explore this characteristic the Gear Research Institute has instrumented and applied a drop-weight stand, shown below, to subject gear teeth to impact loads.  A triggered release mechanism, which travels with the drop weight, is utilized to set the drop height and release the drop weight to initiate the test.  The mass of the drop weight can be increased by adding dead weights on either side of the drop weight.  A load cell, between the drop weight and the load anvil, measures the actual impact. By varying the drop height and the actual mass of the drop weight, the gear tooth can be subject to different amounts of impact energy, at various rates.  Several sponsored programs are currently utilizing this test equipment to evaluate the impact characteristics of their gears.