Mechanical Engineering Gear Creation of Gears This article is reproduced with the permission. Masao Kubota, Haguruma Nyumon, Tokyo : Ohmsha, Ltd., 1963. What is a gear ? A gear is a kind of machine element in which teeth are cut around cylindrical or cone shaped surfaces with equal spacing. If it is difficult to view PDF, please consult these sections. Types of Gears Spur gear Helical gear Ratchet Pawl Rack Pinion Straight bevel gear Spiral bevel gear Worm Worm wheel Internal gear Gear coupling Screw gear Involute spline shafts and bushings Miter gear There are many types of gears such as spur gears, helical gears, bevel gears, worm gears, gear rack, etc. Gears can be classified by shape as involute, cycloidal and Trophies gears. There are straight miter and spiral miter gears. Even after choosing the general type, it is important to consider factors such as: dimensions (module, number of teeth, helix angle, face width, etc.), standard of precision grade...