Oilers/Plant Tenders (HHC) Civil Service Practice Exam

To transmit power between two shafts that are in the same plane but 90° to each other, it is BEST to use ________ gears.

1. Spur

2. Crown

3. Bevel

4. Worm

The correct answer is: Bevel

In mechanical systems where there is a need to transmit power between two shafts that are positioned at a right angle (90°) to each other, bevel gears are the most appropriate choice. Bevel gears are specifically designed for such applications, allowing for efficient power transfer and rotation changes at right angles. Bevel gears come in various configurations, such as straight, miter, and spiral types, enabling them to effectively handle the angular displacement associated with the shafts. Their design allows for smooth meshing and operation, making them suitable for a wide range of applications including in automotive, industrial machinery, and other mechanical devices where space constraints or directional changes are important. Other gear types, such as spur gears, are not suited for 90° shaft arrangements as they align parallel to each other and cannot facilitate the required angular motion. Crown gears (a type of bevel gear, specifically used in certain configurations) can fulfill this role, but bevel gears are the broader category that encompasses the necessary design for right-angle transmission. Worm gears, while capable of providing high gear reduction ratios and allowing for non-parallel shaft arrangements, also do not meet the requirement for direct 90° transmission in an optimal manner compared to bevel gears. Thus, bevel gears are recognized as the best