MDE 2 Q1

Answer: B) To maintain a seal between the piston and cylinder wall, control oil consumption, and support combustion pressure
Explanation: Piston rings are necessary to:

1. Maintain a Seal: They create a seal between the piston and the cylinder wall, preventing combustion gases from escaping and ensuring efficient power generation.
2. Control Oil Consumption: They help control the amount of oil that lubricates the cylinder wall, reducing oil consumption and preventing excessive oil from entering the combustion chamber.
3. Support Combustion Pressure: They support the combustion pressure by maintaining proper compression and helping to transfer force from the piston to the crankshaft effectively.

Answer: A) High thermal conductivity, low wear rate, and effective sealing
Explanation: Desirable properties of piston rings include high thermal conductivity to dissipate heat, low wear rate to ensure long service life, and effective sealing to prevent combustion gases from escaping and to control oil consumption. These properties help maintain engine performance and efficiency over time.

Answer: A) End clearance, radial clearance, and side clearance
Explanation: For efficient piston ring functioning, the following three clearances are necessary:

1. End Clearance: This allows for thermal expansion of the piston rings to prevent binding.
2. Radial Clearance: This is the space between the piston ring and the cylinder wall, ensuring proper sealing and preventing excessive friction.
3. Side Clearance: This is the clearance between the piston ring and the ring groove in the piston, allowing for thermal expansion and maintaining proper ring movement.

Answer: A) Butt, tapered, and bevel
Explanation: The three different types of piston ring ends are butt, tapered, and bevel. These types refer to the shape and design of the ends of the piston rings, which affect how they interact with the cylinder walls and the overall sealing performance.

Answer: A) To allow for thermal expansion, prevent binding, and ensure smooth operation
Explanation: The necessary clearances for piston rings are crucial to:

1. Allow for Thermal Expansion: Ensuring that the piston rings can expand with heat without binding in the cylinder.
2. Prevent Binding: Avoiding the risk of piston rings becoming stuck in the cylinder due to expansion.
3. Ensure Smooth Operation: Maintaining proper movement and sealing of the piston rings to support efficient engine performance and longevity.

Answer: A) To allow for thermal expansion and prevent the rings from binding in the cylinder
Explanation: Piston ring end clearance is necessary to accommodate thermal expansion of the piston rings as they heat up during engine operation. Without adequate clearance, the rings could expand and bind in the cylinder, leading to potential damage and reduced engine performance. The clearance ensures smooth operation and proper sealing throughout the engine's temperature range.

Answer: A) Cast iron, chrome-plated steel, and high-carbon steel
Explanation: Piston rings are commonly made from materials such as cast iron, chrome-plated steel, and high-carbon steel. These materials are chosen for their durability, wear resistance, and ability to withstand the high pressures and temperatures inside the engine.