Moya Rodríguez

Gear drives occupy a very important place in modern technology. Many devices are equipped with this type of transmission. Among the most commonly used gear drives are external cylindrical gear drives, which have been extensively researched. No less important and used are the transmissions by cylindrical gears with internal teeth, which are used in numerous planetary mechanisms, gearboxes, etc., although there is very little literature on these types of transmissions, although there is very little literature dealing with the subject separately.Most of the authors of engineering textbooks express that these transmissions should be treated for their calculation and design the same as the external ones with some changes of sign in the expressions, however this is imprecise, since the internal gears present different geometric particularities, the contact stresses are lower than in external gears, product of the convex - concave contact of the external gear with the internal one, the covering coefficient and therefore the load distribution differ, they reach greater durability, etc.