NCCER Millwright Practice Exam

What is a characteristic feature of bevel gears?

1. They have no sliding motion

2. They are less efficient than spur gears

3. They have no gears at all

4. They have no axial thrust

The correct answer is: They have no axial thrust

Bevel gears are designed to transmit power between shafts that are typically oriented at right angles to each other. One of the defining characteristics of bevel gears is that they are constructed to minimize axial thrust. This means that during operation, they do not generate a significant amount of axial load along their axis of rotation. The design of bevel gears allows them to achieve efficient transfer of motion without creating excess force that could lead to wear or failure of bearings or housing, which are essential in maintaining the longevity and efficiency of machinery. Therefore, the absence of axial thrust is a significant advantage in their application, as it contributes to smoother operation and reduced mechanical stress. In contrast, other gears such as helical gears do produce axial thrust due to their angled teeth, which can require additional bearing support. Understanding this aspect of bevel gears is crucial for millwrights when selecting appropriate gears for machinery and ensuring effective performance in mechanical systems.