Question

A shaft carries a helical spur gear. Which one of the following bearings can NOT be used to support it?

• A. Angular contact bearing
• B. Double-row ball bearing
• C. Straight roller bearing
• D. Tapered roller bearing

Hint:

When selecting bearings for gear shafts, always consider the type of load (radial vs. axial) generated by the gear type (e.g., helical vs. spur) to ensure proper support.

Answer 1

The Correct Option is C

Step 1: Understanding the gear and bearing interaction
Helical gears, which are commonly used in gearboxes, produce both radial and axial forces during operation. Bearings used to support such shafts must be capable of handling both of these types of forces.

Step 2: The role of different bearings
- Angular contact bearings are designed to handle both radial and axial loads. They are ideal for supporting shafts carrying helical gears, as they can accommodate the axial forces generated.
- Double-row ball bearings also handle both radial and axial loads, making them suitable for helical gears.
- Straight roller bearings are designed primarily to handle radial loads and are not well-suited for axial loads, making them an inappropriate choice for a shaft carrying a helical spur gear.
- Tapered roller bearings are designed to handle both radial and axial loads, especially in applications where the axial forces are significant, such as in shafts carrying helical gears.

Step 3: Analyzing the options
- Option (A), (B), and (D) all describe bearings that can handle both radial and axial forces, making them suitable for use with helical spur gears.
- Option (C), straight roller bearing, is not suitable because it cannot effectively support the axial forces generated by helical gears.

Step 4: Conclusion
Thus, the correct answer is (C) Straight roller bearing, as it cannot support the shaft with a helical spur gear.