433A Mechanical Drives and Bearings 3 — Questions and Answers
Question 1: What is the primary reason for using a spherical roller bearing in heavy industrial applications?
- It is the least expensive option
- It is self-aligning and handles heavy radial and axial loads (Correct answer)
- It operates at the highest speeds
- It requires no lubrication
Correct answer: It is self-aligning and handles heavy radial and axial loads
Spherical roller bearings feature a spherical outer raceway that allows them to self-align, accommodating shaft deflection and housing misalignment while carrying very heavy radial and moderate axial loads.
Question 2: When installing a press-fit bearing on a shaft, what is the recommended heating temperature for the bearing?
- Up to 50°C (122°F)
- Up to 120°C (250°F) (Correct answer)
- Up to 200°C (392°F)
- Up to 300°C (572°F)
Correct answer: Up to 120°C (250°F)
Bearings should be heated to a maximum of approximately 120°C (250°F) for installation. Exceeding this temperature can alter the metallurgical properties of the bearing steel and damage seals or shields.
Question 3: What does AGMA stand for in relation to gear standards?
- American Gear Maintenance Association
- American Gear Manufacturers Association (Correct answer)
- Applied Gear and Machinery Association
- Automated Gear Manufacturing Alliance
Correct answer: American Gear Manufacturers Association
AGMA stands for American Gear Manufacturers Association, which establishes industry standards for gear design, manufacturing, rating, lubrication, and inspection.
Question 4: In a timing belt drive, what happens if a tooth shears off the belt?
- The belt slips gradually and speed decreases
- The drive loses synchronization between shafts (Correct answer)
- The belt stretches to compensate
- Nothing noticeable occurs until complete failure
Correct answer: The drive loses synchronization between shafts
Timing belts are positive-drive components that maintain exact synchronization between shafts. If teeth shear off, the precise timing relationship is lost, which can cause equipment damage or product defects.
Question 5: What is the correct way to check bearing clearance using a feeler gauge on a plain bearing?
- Insert the gauge between the shaft top and bearing cap (Correct answer)
- Insert the gauge between the shaft bottom and bearing shell
- Measure at both sides of the shaft horizontally
- Place the gauge between the two bearing halves at the split line
Correct answer: Insert the gauge between the shaft top and bearing cap
Bearing clearance in a plain (sleeve) bearing is checked by inserting a feeler gauge between the top of the shaft and the top bearing shell (cap) to measure the oil clearance gap.
Question 6: Which factor most directly affects the L10 life rating of a rolling element bearing?
- Operating temperature
- Applied load relative to the dynamic load rating (Correct answer)
- Shaft surface finish
- Housing material
Correct answer: Applied load relative to the dynamic load rating
The L10 bearing life is calculated based on the ratio of the bearing's dynamic load rating (C) to the applied equivalent load (P). Life varies with the cube of this ratio for ball bearings and the 10/3 power for roller bearings.
433A Mechanical Drives and Bearings 3
What is the primary reason for using a spherical roller bearing in heavy industrial applications?