Something About Spur Gears and Helical Gears
Spur gear is the simplest type of gear which consists of a cylinder or disk. Its form is not straight-sided, thus, the edge of each tooth is straight and aligned parallel to the axis of rotation. It is the most basic and available type. As the most common type, spur gears are often used because they are the simplest to design and manufacture. Besides, they are the most efficient. Gear teeth could be manufactured with a wide variety of shapes and profiles. Nowadays, the involute profile is the most commonly used system for gearing. An involute is a curve that is traced by a point on a taut cord unwinding from a circle, which is called a base circle. The involute is a form of spiral, the curvature of which becomes straighter as it is drawn from a base circle and eventually would become a straight line if drawn far enough. In recent years, it is usual to set the pressure angle to 20 degrees. In commercial machinery, it is most common to use a portion of an involute curve as the tooth pro...