Which of the following governing methods is used for gas engines? 

Explanation:

Hit-and-Miss Governing:

• Hit-and-miss governing is a type of speed governing method used primarily in gas engines.
• In this method, the engine is designed to run at a constant speed, and the governor controls the engine speed by allowing or preventing the fuel supply to the engine.
• This method involves "hitting" (allowing the fuel to ignite) and "missing" (cutting off the fuel supply) cycles based on the speed requirements.

Important Points

• This governing method is highly effective in maintaining the desired speed of gas engines.
• It is commonly used in small stationary engines, such as those used in agricultural machinery and generators.

Additional Information

Other governing methods used in engines include:

1. Controlled Governing:

• In controlled governing, the fuel supply is continuously regulated to maintain the engine speed.

2. Quantity Governing:

• Quantity governing involves controlling the amount of air-fuel mixture supplied to the engine to regulate its speed.

3. Quality Governing:

• Quality governing involves varying the quality or richness of the air-fuel mixture supplied to the engine to control its speed.

Conclusion: The correct answer is option 4, as hit-and-miss governing is the specific method used for gas engines to maintain their speed by alternately allowing and cutting off the fuel supply.