Porter Governor is a modification of Watt Governor with central load attached to the sleeve. This load moves up and down the central spindle. The additional force increases the speed of revolution required to enable the balls to rise to any predetermined level.

1. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
1
Lecture – III
Governor
Topics
 Porter, Proell governor and its construction
Porter Governor
Porter Governor is a modification of Watt Governor with central load attached to the sleeve.
This load moves up and down the central spindle. The additional force increases the speed of
revolution required to enable the balls to rise to any predetermined level.
Construction:-
Porter governors have two fly balls which are attached to the arms of the porter governor.
These two arms are pivoted to the top of the spindle. This spindle is driven by the engine. The
parts of the arms just above the fly balls are connected to the central sleeve. This sleeve
moves up and down according to the movement of the balls. There are stoppers place in the
spindle to limit the vertical movement of the spindle. This sleeve is carries a heavy central
load. The movement of the sleeve controls opening and closing of the throttle valve.
Working:-
When the load of engine decreases, there will be sudden increase in speed of engine and
spindle speed will also increase. As the spindle speed increases two fly balls also start
rotating around the spindle fast. The centrifugal force will push the balls outward making the
balls move in upward direction. Since the ball moves upward , the arms also moves upward
and the sleeve connected to the lower part of the arm also moves upward. Upward movement
of sleeve actuates the throttle valve via a mechanism connected to the sleeve to decrease the

2. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
2
fuel supply to the engine. The decreases in fuel supply decreases the speed. Hence speed is
maintained.
In the other case, when the load of the engine increases speed of the engine decreases. As the
engine speed decreases, speed of the spindle also decreases and centrifugal force in the balls.
Hence the balls come down with the arms. As the arms comes down, the sleeve connected to
the arm also comes down and it actuates the throttle valve which increase the fuel supply.
Due to increase in fuel supply, speed of engine also increases.

3. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
3
Functional Working
 These balls will be revolving around the spindle which is driven by the engine.
 As you can see the above schematic diagram of a porter governor, there are links
joined to a sleeve where it can translate on the spindle freely.
 A central load of W is added on the sleeve to increase the revolution speed of the balls
required to lift the sleeve on the spindle.
 A bell crank lever is connected to the sleeve and the other end of it will be connected
to throttle valve located in the fuel supply passage.
 As the engine working, these balls also revolving around the spindle at a certain speed
and maintained at a mean position radially with the speed of the engine due to the
centrifugal force.
 Whenever there is a decrease in the engine speed due to the load, then the speed of the
balls also changes and due to the less centrifugal force outwards, the balls revolve bit
lower their means radial position.
 Then the sleeve connected by the links will automatically move downwards on the
spindle, the bell crank lever opens the throttle valve to pass the more amount of fuel.
So that the engine speed will be increased to its mean speed.
This is how the Porter Governor works to govern the fuel supply and regulates the mean
speed of the engine when there is a variation in the load.

4. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
4

5. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
5

6. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
6
2. When the loaded sleeve moves up and down the spindle, the frictional force acts on it in a
direction opposite to that of the motion of sleeve.
Proell Governor
Theory
Governors, in general, are most useful means of controlling or regulating the speed of an
engine based on varying levels of the load at the output. They are used in regulating the speed
of the engine, which takes to the fact that the fuel injected is based on the speed variations
seen along the shafts.
Proell governor is a type of gravity controlled centrifugal governor. The centrifugal governor
works on the principle of centrifugal force, which gets applicable on the rotating balls. These
balls are known as fly balls, which are attached to the spindle through links. The balls rotate
with a spindle which is rotated by the engine through a bevel gear. The upper ends of the
arms are pivoted to the spindle, so that the balls may rise up or fall down as they revolve
about the vertical axis. The arms are connected by the links to a sleeve, which is keyed to the
spindle. This sleeve revolves with the spindle; but can slide up and down. The balls and the
sleeve rise when the spindle speed increases, and falls when the speed decreases. This
controls the throttle valve thus regulating the fuel intake of the engine, hence controlling the
speed. In Proell governor, fly balls are attached to the upward extension of the link and
central load attached to the sleeve.

7. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
7

8. LNCT GROUP OF COLLEGES
Name of Faculty: Prem Kumar Soni
Designation: Assistant Professor
Department: Mechanical Engineering
Subject: Theory of Machines (403)
Unit: 6
8