Short Answer:

Governors are devices used in engines to control and regulate their speed automatically by adjusting the fuel supply. They are mainly classified into two broad types: centrifugal governors and inertia governors. Centrifugal governors work on the principle of centrifugal force, while inertia governors depend on the angular acceleration of the engine shaft.

Further, centrifugal governors are divided into several types such as Watt, Porter, Proell, and Hartnell governors. Each type has its own mechanism and design to control engine speed according to load changes.

Detailed Explanation:

Types of Governors

Governors are essential mechanical devices used in engines and machines to maintain a nearly constant speed under varying load conditions. When the load on an engine increases, its speed decreases, and when the load decreases, the speed increases. To avoid such fluctuations, governors automatically adjust the fuel supply to bring the speed back to the desired mean value. Depending on their operating principles and construction, governors are mainly divided into two major types:

1. Centrifugal Governors
2. Inertia Governors

Let us discuss these types in detail.

1. Centrifugal Governors

Centrifugal governors are the most commonly used type in engines. They operate on the principle of centrifugal force, which acts on rotating masses when they move in a circular path.

When the speed of the engine shaft increases, the centrifugal force on the rotating balls (masses) increases. This causes the balls to move outward and lift the sleeve upward through a system of links. The upward movement of the sleeve reduces the fuel supply, decreasing the engine speed. Similarly, when the engine speed decreases, the balls move inward, lowering the sleeve, and the fuel supply increases to restore the speed.

Types of Centrifugal Governors

Centrifugal governors are further divided into the following types based on their construction and working mechanism:

(a) Watt Governor:
It is the simplest type of centrifugal governor. It consists of two balls attached to arms, which are connected to a vertical spindle. As the speed increases, the balls move outward due to centrifugal force, lifting the sleeve. This movement controls the fuel valve. However, it works efficiently only at low speeds and is not suitable for high-speed engines.

(b) Porter Governor:
This governor is a modification of the Watt governor. It includes a heavy central load on the sleeve, which increases the controlling force. This makes it more sensitive and suitable for moderate-speed engines.

(c) Proell Governor:
It is another improved version of the Porter governor. The difference lies in the attachment of the links carrying the balls. This arrangement increases the efficiency and reduces the sleeve lift required for a given speed change, making it more stable and compact.

(d) Hartnell Governor:
The Hartnell governor is a spring-loaded type centrifugal governor. Instead of dead weights, a spring provides the controlling force. This design makes it more responsive and suitable for high-speed engines, such as in modern automobiles. It also allows adjustment of speed range by changing the spring stiffness.

(e) Hartung Governor:
This is similar to the Hartnell governor but has spring arms directly attached to the frame. It provides quicker response and better stability.

2. Inertia Governors

Inertia governors work on a different principle compared to centrifugal governors. In these, the governor balls are affected by the inertia forces that act due to angular acceleration or deceleration of the engine shaft.

When the engine speed increases suddenly, the inertia of the rotating balls causes them to move outward, which lifts the sleeve and reduces the fuel supply. Conversely, when the speed decreases, the inertia of the balls causes them to move inward, lowering the sleeve and increasing the fuel supply.

In inertia governors, the controlling force depends on both the centrifugal and inertia effects. They respond more quickly to speed changes compared to centrifugal types, making them useful where rapid load variations occur. However, their design and maintenance are more complex, which limits their practical use.

Comparison Between Centrifugal and Inertia Governors

• Operating principle:
  Centrifugal governors depend on centrifugal force, whereas inertia governors depend on the inertia of the rotating parts.
• Response time:
  Inertia governors respond faster to speed changes than centrifugal types.
• Construction:
  Centrifugal governors have simpler designs and are easier to maintain.
• Use:
  Centrifugal governors are widely used in steam, gas, and oil engines, while inertia governors are used in special high-speed applications.

Conclusion:

Governors play a vital role in maintaining uniform engine speed by automatically regulating the fuel supply. Based on their working principle, governors are classified mainly into centrifugal and inertia types. Centrifugal governors like Watt, Porter, Proell, and Hartnell are most commonly used due to their simple design and reliable operation. Inertia governors, though faster in response, are more complex and less common. The selection of a suitable governor depends on the type of engine, speed range, and stability requirements.