Millwright Certification Power Transmission and Drive Systems 1 — Questions and Answers
Question 1: What is the primary purpose of a V-belt drive in industrial machinery?
- To transmit power between shafts using friction between the belt and sheave grooves (Correct answer)
- To provide electrical power to rotating machinery
- To cool the motor during operation
- To synchronize two shafts at identical speeds
Correct answer: To transmit power between shafts using friction between the belt and sheave grooves
V-belt drives transmit power through friction between the trapezoidal belt and the angled grooves of the sheave.
Question 2: When installing a roller chain drive, the maximum allowable sag for a horizontal chain is typically:
- 1–2% of the center distance (Correct answer)
- 5–10% of the center distance
- 10–15% of the center distance
- No sag is permissible
Correct answer: 1–2% of the center distance
Horizontal roller chains should have approximately 1–2% sag of the center distance to allow for thermal expansion and prevent over-tensioning.
Question 3: A gear ratio of 4:1 means the output shaft turns:
- One revolution for every four revolutions of the input shaft (Correct answer)
- Four revolutions for every one revolution of the input shaft
- At four times the torque of the input with equal speed
- At the same speed but with four times the power
Correct answer: One revolution for every four revolutions of the input shaft
A 4:1 gear ratio means the output shaft completes one revolution for every four revolutions of the input shaft, reducing speed and increasing torque.
Question 4: What type of coupling is best suited for connecting two shafts with significant angular misalignment?
- Jaw coupling
- Rigid flange coupling
- Grid coupling
- Gear coupling (Correct answer)
Correct answer: Gear coupling
Gear couplings can accommodate angular, parallel, and axial misalignment, making them suitable for applications with significant angular misalignment.
Question 5: Which belt drive arrangement is used to reverse the direction of the driven shaft?
- Open belt drive
- Cross belt drive (Correct answer)
- Compound belt drive
- Quarter-turn belt drive
Correct answer: Cross belt drive
A cross belt drive (also called a crossed belt) causes the driven shaft to rotate in the opposite direction of the driver shaft.
Question 6: When aligning a sheave on a shaft, which tool is most commonly used to check alignment between two sheaves?
- Dial indicator
- Feeler gauge
- Straight edge or laser alignment tool (Correct answer)
- Micrometer
Correct answer: Straight edge or laser alignment tool
A straight edge placed across the faces of both sheaves (or a laser alignment tool) is used to verify coplanar alignment and prevent premature belt wear.
Millwright Certification Power Transmission and Drive Systems 1
What is the primary purpose of a V-belt drive in industrial machinery?