FAA Powerplant Written Practice Test

What type of bearings are master rod bearings generally classified as?

1. Ball bearings

2. Roller bearings

3. Plain bearings

4. Journal bearings

The correct answer is: Plain bearings

Master rod bearings are generally classified as plain bearings due to their structure and function. Plain bearings, also known as sliding bearings, have a simple design consisting of two surfaces that slide against each other. This type of bearing relies primarily on the lubrication to reduce friction between the surfaces during operation. In the context of aircraft engines, master rod bearings are crucial for supporting the connecting rod and allowing it to pivot smoothly about the crankshaft. These bearings are designed to handle the axial and radial loads applied during operation while providing a reliable surface for movement without the complexities associated with other bearing types. While options like ball, roller, and journal bearings have specific applications and designs that may utilize rolling elements to reduce friction, master rod bearings' plain bearing classification emphasizes their simple design and utility in aviation engine applications, which require effective load management and lubrication to ensure optimal performance and longevity.