In involute teeth, the pressure angle is defined as the angle between which two lines?

In involute gearing, the pressure angle is a critical concept defining the interaction between meshing gears. It is specifically defined as the angle between the line of action, which is the line along which the force is transmitted between the two gears, and the tangent to the pitch circle at the point of contact.

The pitch circle represents the circle at which the gears theoretically engage and is crucial for determining the size and spacing of the teeth. When examining the pressure angle, one can visualize how the forces are directed in the system. The line of action makes an angle with the tangent to the pitch circle due to the geometry of the involute tooth profile, which ensures that the contact occurs smoothly and efficiently as the gears rotate.

This definition is essential because the pressure angle affects the tooth design, load distribution, and surface wear on the gears, influencing performance characteristics such as strength, noise, and the ability to handle misalignment. Therefore, understanding the relationship between the line of action and the tangent to the pitch circle is fundamental in gear design and analysis.