Involute gears

involute gears

involute gearsInvolute gears have a tooth shape that is tolerant of variations in the distance between the axes, to ensure smooth running of the gears. The velocity ratio of the gears does not depend on the exact spacing of the axes, but is fixed by the number of teeth or by pitch
diameters. Increasing the distance above its theoretical value makes the gears run easier, since the clearances are larger. This also increases the backlash. Rack type cutters generate  involute gears. The involute gear profile is the most commonly used system for gearing today.