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1. CENTRIFUGAL GOVERNORS
NISHANT SINGH
130530104034
MECHANICAL 3rd YEAR

2. INTRODUCTION
 The function of a governor is to regulate the
mean speed of an engine, when there are
variation in load.
 When the load increases, the configuration of
the governor changes and a valve is moved to
increases the supply of the working fluid;
conversely when the load decreases, the engine
speed increases and the governor decreases the
supply of working fluid.
 The governor automatically controls the supply
of working fluid to the engine with the varying
load conditions and keeps the mean speed
within certain limits.

3. Types of GOVERNORS:-
The Governors may, broadly, be classified as
1.Centrifugal governors,
2.Inertia governors
CENTRIFUGAL GOVERNORS

4. CENTRIFUGAL GOVERNORS:-
 The centrifugal governors are based on the
balancing of centrifugal force on the rotating balls
by an equal and opposite radial force known as
the controlling force.

5.  It consist of two balls of equal mass, which
are attached to the arms.
 These balls are known as governor balls or fly
balls. The balls revolve with a spindle, which
is driven by the engine through bevel gears.
 The upper end of arms are pivoted to the
spindle, so that the balls may rise up or fall
down as they revolve about the vertical axis.
 The arm are connected by the links to a
sleeve, which is keyed to the spindle. This
sleeves revolves with the spindle; but can
slide up and down.
 The balls and the sleeve rises when the
spindle speed increases, and falls when the
speed decreases.

6.  In order to limit the travel of the sleeve in
upwards and downward direction, two stops S, S
are provided on the spindle.
 The sleeve is connected by a bell crank lever to a
throttle valve.
 The supply of working fluid decreases, the engine
and the governor speed decreases.
 The results in decrease of centrifugal force on
the balls. Hence the balls move inwards and the
sleeve moves downwards.
 The download movement of the sleeve operates a
throttle valve at the other end of the bell crank
lever to increase the supply of working fluid and
thus the engine speed is increased.

7.  When the load on the engine decreases, the engine
and the governor speed increases, which results in
the centrifugal force on the balls.
 Thus the balls move outwards and the sleeve rises
upwards.
 This upward movement of the sleeve reduces the
supply of the working fluid and hence the speed is
decreased. In this case, the power output is
reduced.

9. Terms Used in Governors:-
 Height of governor: it is vertical distance from
the centre of the ball to a point where the axes of
arms intersect on the spindle axis. It is usually
denoted by h.
 Equilibrium speed: it is the speed at which the
governor balls, arms etc., are in complete
equilibrium and the sleeve does not tend to move
upwards or downwards.
 Sleeve lift: it is the vertical distance which the
sleeve travels due to change in equilibrium speed.
 Maximum and minimum equilibrium speed: the
speed at the maximum and minimum radius of
rotation of balls, without tending to move either
way are known as maximum and minimum
equilibrium speeds respectively.

10. Working of Centrifugal Governor:-

11. Characteristics of Governors:-
 Stability: A governor is said to be stable when there
is one radius of rotation of the balls for each speed
which is within the speed range of the governor.
 Sensitiveness: The smaller the change in speed
from no load to the full load, the more sensitiveness
of the governor shall be the determined by the ration
of speed range to the mean speed. The smaller the
ratio more sensitive the governor will be.
 Isochronism: A governor is said to be isochronous if
equilibrium speed is constant for all the radii of
rotation in the working range. Therefore, for an
isochronous governor the speed range is zero and this
type of governor shall maintain constant speed.
 Hunting: A governor is said to be hunt if the
speed of the engine fluctuates continuously
above and below the mean speed

12. Effort and Power of a Governor:-
 The effort of a governor is the mean force
exerted at the sleeve for a given percentage
change of speed.
 The power of a governor is the work done at the
sleeve for a given percentage change of speed. It
is the product of the mean value of the effort
and the distance through which the sleeve
moves.
Power = Mean effort * lift of sleeve

13. Watt Governor:-
 The simplest form of a
centrifugal governor is a
Watt governor.
 It consist of two balls
attached with the arm and
link, lower arm pivoted on
the sleeve and upper arm
attached to spindle.

14. Porter Governor:-
 In Porter governor central load is attached to the sleeve
 The load moves up and down the central spindle. This
additional downward force increases the speed of
revolution required to enable the balls to rise to any
predetermined level.

16. Hartnell Governor:-
 A Hartnell governor is a spring loaded governor. It
consist of two bell crank levers pivoted at the point B,
B to the frame.

17.  The frame is attached to the governor spindle
and therefore with it
 Each lever carries a ball at the end of the
vertical arm and a roller at the end of the
horizontal arm.
 A helical spring in compression provides equal
downward force on the two rollers through a
collar on the sleeve.
 The spring may be adjusted by screwing a nut up
or down on the sleeve.

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