Governor Systems: Understanding Speed Control

A governor is a crucial device used in engines and turbines to regulate and maintain a near-constant speed, especially when the load on the prime mover changes. Its primary function is to control the supply of working fluid (like fuel or steam) to the engine, ensuring that the engine speed remains within desired limits regardless of variations in the power demand.

Governors are broadly classified into two main types:

• Centrifugal Governors: These governors operate on the principle of centrifugal force. As the engine speed increases, the centrifugal force acting on rotating masses (balls) increases, causing them to move outwards. This outward movement is then used to control the fuel supply.
• Inertia Governors: These governors respond to the rate of change of speed (acceleration or deceleration) rather than the absolute speed.

Centrifugal Governor Classification

Centrifugal governors are further categorized based on how the controlling force is generated and balanced:

• Dead-weight Governors: In these governors, the controlling force is provided by gravity acting on a dead weight. Examples include Watt and Porter governors.
• Spring-Controlled Governors: In these governors, the controlling force is provided by springs. As the speed changes, the centrifugal force of the rotating masses is balanced by the spring force. This type of governor is known for its higher speed range and sensitivity compared to dead-weight governors.

Types of Spring-Controlled Governors

Several types of governors fall under the category of spring-controlled governors due to their reliance on springs for their operation. Let's examine the types mentioned in the options:

Hartnell Governor

The Hartnell governor is a widely used and common type of spring-controlled centrifugal governor. Its key features include:

• It uses bell-crank levers, with balls attached to one end and rollers at the other, which are in contact with a sleeve.
• A spring (or a set of springs) directly controls the movement of the sleeve. The compression or tension of this spring provides the controlling force that balances the centrifugal force of the rotating balls.
• As the speed increases, the balls move outwards, lifting the sleeve and compressing the spring, which then adjusts the fuel supply.

Hartung Governor

The Hartung governor is another example of a spring-controlled governor. It is a variation of the Hartnell type, characterized by:

• The springs in a Hartung governor are typically attached directly to the arms of the governor balls, rather than acting on the sleeve through levers.
• This direct attachment often leads to a more compact design and specific performance characteristics in terms of sensitivity and stability. The spring force directly opposes the centrifugal force of the balls.

Pickering Governor

The Pickering governor is a unique and distinct type of spring-controlled governor, particularly known for its use in gramophones and other light machinery, although it has broader applications. Its distinguishing characteristics include:

• It does not use ball weights like other centrifugal governors. Instead, it employs three or more flat leaf springs arranged around the governor spindle.
• Small weights are attached to the center of these leaf springs. As the spindle rotates, the centrifugal force acts on these small weights, causing the leaf springs to flex outwards.
• The deflection of these springs then operates the throttle valve or control mechanism. The flexibility and stiffness of the leaf springs provide the necessary controlling force.

Conclusion on Spring-Controlled Governors

Based on the operational principles and design of the governors discussed, it is clear that Hartnell, Hartung, and Pickering governors all rely on the action of springs to provide the controlling force that balances the centrifugal force of the rotating masses (or the equivalent force in the case of Pickering). Therefore, all these types fall under the classification of spring-controlled governors.