Gears: machining, efficiency. Planetary gears

In this final article on gears, we give a general (paragraph 1) but very brief overview of gear manufacturing methods. The machines used are often very complicated, and a more detailed study would only be of interest to the manufacturers themselves. It's worth noting that many companies, once very important, have disappeared or merged.

Paragraph 4 is extremely important, as the use of planetary gear trains is becoming increasingly common. We'll just give you the basics for the most common planetary gears.