NCCER Millwright Practice Exam

What type of thrust is associated with inward axial movement in machinery?

1. Radial thrust

2. Outward axial thrust

3. Inward axial thrust

4. Universal thrust

The correct answer is: Inward axial thrust

Inward axial thrust refers to the force that pushes components of machinery towards the center or axis of rotation. This type of thrust is important in applications where gear systems, bearings, or other rotating machinery parts need to maintain alignment and prevent displacement. Inward axial thrust can occur in situations where the dynamics of the assembly or machine demand components to be held together tightly, preventing excessive movement that could lead to mechanical failure or inefficiency. Understanding the mechanics of inward axial thrust is essential for millwrights, as it plays a crucial role in the design and maintenance of machinery. For instance, in a vertical turbine, the pump may induce inward axial thrust due to the fluid dynamics involved, necessitating design considerations for bearings and supports that accommodate such forces. The other types of thrust do not directly correspond to this inward movement. Radial thrust typically acts perpendicular to the axis and involves forces that can cause components to move outward rather than inward. Outward axial thrust describes forces pushing away from the center, and universal thrust, while not a standard term in every context, generally does not specifically describe a movement toward the axis. This understanding emphasizes the distinct nature of inward axial thrust within the context of machinery operation and maintenance.