433A Mechanical Drives and Bearings 1 — Questions and Answers
Question 1: What is the primary purpose of a keyway in a shaft-to-hub connection?
- To reduce shaft vibration
- To transmit torque between the shaft and the component (Correct answer)
- To allow axial movement of the component
- To lubricate the bearing surface
Correct answer: To transmit torque between the shaft and the component
A keyway and key create a positive mechanical connection that transmits torque from the shaft to the mounted component such as a gear or pulley.
Question 2: Which type of bearing is best suited for handling both radial and thrust loads simultaneously?
- Cylindrical roller bearing
- Angular contact ball bearing (Correct answer)
- Needle roller bearing
- Thrust ball bearing
Correct answer: Angular contact ball bearing
Angular contact ball bearings are designed with their raceways offset so they can handle combined radial and axial (thrust) loads simultaneously.
Question 3: What is the correct procedure when installing a tapered roller bearing on a shaft?
- Press it on with a hydraulic press using force on the outer race
- Heat the bearing and slide it onto the shaft
- Set the proper endplay or preload using a shim or locknut (Correct answer)
- Apply threadlocker to the shaft before installation
Correct answer: Set the proper endplay or preload using a shim or locknut
Tapered roller bearings require precise endplay or preload adjustment during installation, typically achieved using shims, spacers, or locknuts to ensure proper operation and longevity.
Question 4: In a V-belt drive system, what does excessive belt deflection indicate?
- The belt is too tight
- The belt tension is too low (Correct answer)
- The sheaves are misaligned
- The motor speed is too high
Correct answer: The belt tension is too low
Excessive belt deflection beyond manufacturer specifications indicates insufficient belt tension, which leads to slippage, reduced power transmission, and accelerated belt wear.
Question 5: What is the function of a backstop in a gear reducer?
- To limit the maximum output speed
- To prevent reverse rotation of the driven shaft (Correct answer)
- To dampen vibration during startup
- To lock the gearbox during maintenance
Correct answer: To prevent reverse rotation of the driven shaft
A backstop (anti-reverse device) prevents the output shaft of a gear reducer from rotating in the reverse direction, critical in applications like inclined conveyors where reverse rotation could cause material runback.
Question 6: Which gear tooth profile is most commonly used in industrial power transmission?
- Cycloidal
- Involute (Correct answer)
- Hypoid
- Worm
Correct answer: Involute
The involute tooth profile is the industry standard for spur and helical gears because it maintains a constant velocity ratio even with slight variations in center distance between gears.
433A Mechanical Drives and Bearings 1
What is the primary purpose of a keyway in a shaft-to-hub connection?