1. What is the primary purpose of balancing rotating masses in machines?
a) To reduce friction in bearings
b) To minimize energy consumption
c) To prevent excessive vibrations and improve stability
d) To increase the rotational speed
Answer: c) To prevent excessive vibrations and improve stability
Explanation: Balancing rotating masses in machines is essential to prevent excessive vibrations that can lead to structural damage, decreased efficiency, and even safety hazards. By balancing, the distribution of mass ensures that there are minimal unbalanced forces and moments, thereby improving stability and reducing vibrations.
2. Which balancing technique involves determining balancing masses using both graphical and analytical methods?
a) Single plane balancing
b) Two plane balancing
c) Static balancing
d) Dynamic balancing
Answer: b) Two plane balancing
Explanation: Two plane balancing involves considering balancing masses in two planes to counteract unbalanced forces and moments. It typically requires both graphical and analytical methods to determine the required balancing masses accurately.
3. In engine balancing, what technique is commonly used for balancing single-cylinder engines?
a) Lanchester technique
b) V-twin balancing
c) Radial balancing
d) In-line balancing
Answer: a) Lanchester technique
Explanation: The Lanchester technique is commonly used for balancing single-cylinder engines. It involves adding counterweights to the crankshaft to offset the unbalanced forces generated during the engine’s operation.
4. Which type of engine balancing is often employed for V-twin engines?
a) Static balancing
b) Dynamic balancing
c) Lanchester technique
d) Radial balancing
Answer: b) Dynamic balancing
Explanation: V-twin engines typically require dynamic balancing to minimize vibrations and ensure smooth operation. Dynamic balancing involves counteracting both static and dynamic forces and moments generated by the engine’s moving parts.
5. What is the primary advantage of radial engines in terms of balancing?
a) Easier to balance compared to other engine types
b) Require fewer balancing masses
c) Less susceptible to imbalance effects
d) Better fuel efficiency
Answer: c) Less susceptible to imbalance effects
Explanation: Radial engines have a natural tendency to be less affected by imbalance due to the radial arrangement of cylinders around the crankshaft. This configuration inherently balances the forces generated by the pistons, resulting in smoother operation with fewer balancing requirements.
6. Which method of balancing is based on the principle of adding balancing masses directly to the rotating components?
a) Analytical balancing
b) Graphical balancing
c) Static balancing
d) Dynamic balancing
Answer: c) Static balancing
Explanation: Static balancing involves adding balancing masses directly to the rotating components, such as wheels or rotors, to achieve balance. It is typically used for systems where the distribution of mass can be adjusted without consideration of dynamic forces.
7. What is the purpose of the Lanchester technique in engine balancing?
a) To adjust valve timing
b) To optimize fuel injection
c) To minimize engine vibrations
d) To improve exhaust flow
Answer: c) To minimize engine vibrations
Explanation: The Lanchester technique in engine balancing aims to minimize engine vibrations by adding counterweights to the crankshaft. This helps offset the unbalanced forces generated by the reciprocating motion of the pistons and rods.
8. Which balancing method involves plotting the mass distribution of rotating components on a graph to determine balancing requirements?
a) Analytical balancing
b) Static balancing
c) Graphical balancing
d) Dynamic balancing
Answer: c) Graphical balancing
Explanation: Graphical balancing involves plotting the mass distribution of rotating components on a graph to visualize the imbalance and determine the required balancing masses. It is particularly useful for understanding the spatial distribution of unbalanced forces and moments.
9. In two-plane balancing, where are the balancing masses typically located?
a) On the same plane as the rotating mass
b) On two different planes perpendicular to each other
c) On two planes parallel to each other
d) On the axis of rotation
Answer: b) On two different planes perpendicular to each other
Explanation: In two-plane balancing, the balancing masses are typically located on two different planes perpendicular to each other. This configuration allows for the compensation of unbalanced forces and moments in multiple directions.
10. Which type of balancing is crucial for high-speed rotating machinery?
a) Static balancing
b) Dynamic balancing
c) Graphical balancing
d) Analytical balancing
Answer: b) Dynamic balancing
Explanation: Dynamic balancing is crucial for high-speed rotating machinery to minimize vibrations and ensure stable operation. It involves accounting for both static and dynamic forces and moments generated by the rotating components to achieve balance.