Short Answer:

The sleeve lift is the vertical movement of the governor sleeve along the spindle when the speed of the engine changes. It happens because the governor balls move outward or inward due to the change in centrifugal force.

In simple words, sleeve lift means how much the sleeve moves up or down when the engine speed increases or decreases. This movement helps in adjusting the fuel supply automatically to keep the engine speed constant. The greater the sleeve lift, the more sensitive the governor is in controlling the speed.

Detailed Explanation :

Sleeve Lift

The sleeve lift in a governor refers to the vertical distance through which the sleeve moves up or down along the governor spindle when there is a change in the speed of the engine. This movement is caused by the displacement of the governor balls due to the variation in centrifugal force. As the engine speed increases, the balls move outward, and the sleeve moves upward. Conversely, when the engine speed decreases, the balls move inward, and the sleeve moves downward.

The sleeve lift is an important parameter that indicates how responsive or sensitive a governor is. A greater sleeve lift means the governor can respond more effectively to speed changes, ensuring smooth control of the engine.

1. Construction Related to Sleeve Lift:
   To understand sleeve lift clearly, it is important to know the basic parts of a governor. The governor mainly consists of:

• A spindle connected to the engine shaft, which rotates along with it.
• A pair of fly balls attached to arms and links.
• A sleeve that slides up and down the spindle.
• A throttle valve linkage connected to the sleeve that controls fuel or steam supply.

When the speed of rotation changes, the centrifugal force on the fly balls changes. This force causes the balls to move either outward or inward, leading to the vertical movement of the sleeve. This movement or displacement is termed as the sleeve lift.

2. Working Principle of Sleeve Lift:
   The sleeve lift is based on the principle of centrifugal force. When the governor rotates:

• At low speed, the centrifugal force is less. The fly balls come closer to the spindle, pulling the sleeve down.
• At high speed, the centrifugal force increases. The fly balls move outward, pushing the sleeve upward.

This vertical displacement of the sleeve changes the position of the throttle valve through a mechanical linkage. As a result, the fuel supply is adjusted automatically:

• When the sleeve moves up, the fuel supply is reduced to slow down the engine.
• When the sleeve moves down, the fuel supply is increased to speed up the engine.

Thus, sleeve lift helps in maintaining a nearly constant engine speed by controlling the amount of fuel entering the engine.

3. Factors Affecting Sleeve Lift:
   The amount of sleeve lift depends on several factors:

• Change in engine speed: A larger change in speed produces a greater sleeve lift.
• Mass of the fly balls: Heavier balls produce more centrifugal force, leading to a higher lift.
• Length and position of the governor arms: Longer arms can produce a larger vertical displacement for the same angular movement.
• Spring stiffness (in spring-controlled governors): In spring-controlled governors, the stiffness of the spring affects how much the sleeve can lift for a given speed change.
• Type of governor: Different governors such as Watt, Porter, or Hartnell have different sleeve lift characteristics depending on their design.

Engineers design the governor such that the sleeve lift is sufficient to operate the throttle valve effectively, without being too sensitive to small speed changes.

4. Relation Between Speed and Sleeve Lift:
   The sleeve lift occurs because of the change in centrifugal force, which is directly related to the speed of rotation.
   Let the radius of rotation of the governor balls change from r₁to r₂when the speed changes from N₁ to N₂. The corresponding movement of the sleeve is the sleeve lift (h).

Mathematically, sleeve lift can be expressed as:

where f is a factor that depends on the geometry of the governor arms.

This shows that the sleeve lift is proportional to the change in radius of the governor balls and thus related to the change in engine speed.

5. Importance of Sleeve Lift:
   The sleeve lift plays a key role in the operation of the governor and affects its sensitivity and performance:

• Automatic Speed Regulation: It helps to automatically control the throttle valve position, regulating the engine’s fuel supply.
• Indication of Speed Variation: The magnitude of sleeve lift represents the extent of speed variation in the engine.
• Governor Sensitivity: A larger sleeve lift means the governor can detect small speed changes, making it more sensitive.
• Operational Efficiency: Proper sleeve lift ensures stable operation and avoids frequent or excessive speed fluctuations.
• System Stability: The smooth upward and downward motion of the sleeve prevents sudden fuel supply changes, improving stability.

6. Sleeve Lift in Different Types of Governors:
   Different governors produce different amounts of sleeve lift depending on their design:

• Watt Governor: Produces a small sleeve lift and is suitable for low-speed engines.
• Porter Governor: Has a higher sleeve lift due to the added central load, giving better control at medium speeds.
• Hartnell Governor: Uses a spring to control the sleeve lift, making it more sensitive and compact. It provides large sleeve lift even at small speed variations.

Thus, modern spring-controlled governors like Hartnell are preferred in engines where precise control and high sensitivity are required.

7. Practical Example:
   In a diesel engine, when the load suddenly increases, the engine slows down. This causes the fly balls to come closer to the spindle, moving the sleeve downward. The downward sleeve movement opens the fuel valve wider, supplying more fuel to restore speed. When the load decreases, the sleeve moves upward, closing the valve slightly to reduce fuel supply. This continuous adjustment is made possible because of sleeve lift.

Conclusion:

The sleeve lift is the vertical displacement of the governor sleeve due to changes in engine speed. It represents how much the sleeve moves up or down when the centrifugal force on the governor balls varies. This movement helps to regulate the fuel supply and maintain a constant engine speed. A proper sleeve lift is essential for stable, efficient, and smooth operation of the governor and engine system.