What is NOT a requirement for gears to mesh properly?

Gears must mesh properly to function effectively together, and several key characteristics are critical for their compatibility. Among these characteristics, the requirement for gears to have the same material is not necessary for proper meshing. While it can affect the wear resistance, load capacity, and noise levels, gears made from different materials can still mesh and operate together as long as they share critical geometric and functional properties.

Having the same pressure angle is essential as it dictates the profile of the teeth and affects how the gears interact under load. The same diametral pitch ensures that the spacing of the teeth is consistent, promoting proper engagement. Meanwhile, size is important for ensuring that the gears fit within the spatial constraints of the machinery and maintain appropriate gear ratios. Hence, not being required to be made of the same material allows for greater flexibility in gear design and application.