NCCER Millwright Practice Exam

Which type of coupling has two halves with external teeth and a sleeve with internal teeth?

1. Flexible coupling

2. Rigid coupling

3. Gear coupling

4. Sleeve coupling

The correct answer is: Gear coupling

The correct answer is gear coupling, which is specifically designed for transferring torque between two shafts that may need to be misaligned. In a gear coupling, each half of the coupling features external teeth that interlock, while a flexible sleeve connects them, having internal teeth. This design allows for a significant amount of torque transmission and accommodates misalignment between the two shafts. The design of a gear coupling is particularly advantageous in industrial settings where high torque loads and shaft misalignment can occur, ensuring effective performance and durability. Its ability to handle angular, parallel, and axial misalignment, while still maintaining a secure connection, distinguishes it from other types of couplings, making it ideal for heavy machinery applications. In contrast, flexible couplings generally use elastomeric components or springs to absorb shock and allow for minor misalignment without the complexity of internal and external teeth. Rigid couplings do not provide any flexibility or misalignment accommodation, as they are built to securely fix two shafts in alignment. Sleeve couplings typically consist of a simple cylindrical sleeve that connects two shafts directly, again lacking the tooth configuration characteristic of gear couplings.