Mechanical Basics

What is Watt Governor?

Watt Governor

Watt Governor is a type of governor, an example of Pendulum Type Governor, which is a classification of Mechanical Governor or Centrifugal Governor. It is the most basic and earliest form of the centrifugal governor that is developed by James Watt in the year of 1788. This type of governor construction looks similar to the Mechanical Governor, which consists Two Balls, Arms, etc.  

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Construction of Watt governor

The Watt Governor construction is as simple as it looks. The step by step construction of watt governor is as follows

  • The simple watt governor consists Two balls with certain mass each are positioned on the Sleeves consisting of arms in Watt.
  • The top side of the arm is attached to the Spindle to move the ball in the upward and downward direction.
  • To operate the Throttle Valve, the lower arm is attached to the sleeve, which is joined to the spindle. The spindle is powered by bevel gear, and two stoppers are provided at the bottom and top of the spindle to limit the movement of the sleeves.

Working Principle and Working of Watt governor

As it is already said, the working principle of the watt governor is similar to the centrifugal force. When the load on the engine rises, the angular velocity and speed of the engine both decrease. At constant speed, the controlling force equals to the centrifugal force, which balances each other by the gravity control; however, when the centrifugal force on the balls drops, the balls and spindle begin to move inward and downward directions, respectively.

These motions control the throttle valve mechanism, causing it to open widely and increase the fuel supply to maintain the speed.

Height of a Watt Governor and Its Calculations

Whenever a particular component is supposed to design then there will be a dimension that need to focus more about. So, in the design of a governor, we have focus on the Height of the Watt Governor. So, the Equation to find the height of watt governor is as follows

For the calculation of watt governor, let’s consider the below variable.

m = Mass of each ball in kilogram (Kg).

W = Weight of each ball in Newton (N) = m.g

T = Tension in the arms in Newton (N)

ω = Angular Velocity of the arm ball and sleeve along the spindle in radians/seconds

r = Radial distance of the ball from the center spindle axis.

Fc = Centrifugal Force exerted on the ball in Newtons = m.ω^2.r

h = Height of the Watt Governor from point O in meters

Construction of Watt Governor

It is assumed that

  • the sleeve is frictionless,
  • the weight of links is negligible.

Now the ball is in equilibrium under the action of the Centrifugal force acting on the balls

Fc = m.ω2.r

The weight of balls w = mg

Tension in the upper arms = T

There is no tension in the lower arms because it is assumed the sleeve is frictionless and the weight of the arms is negligible.

Then the Sleeve Lift = 2 [h2 – h1]

Where h1 sleeve position at speed N1 and h2 sleeve position at speed N2.

Height of Watt Governor

We can also write the above equation in another way as follows by taking the moment of these forces along with point O. For equilibrium

Watt Governor Height Formula

We can conclude from the previous equation that speed is inversely related to governor height. As a result, at high speeds, the value of h is small.

Because of the short height of the watt governor, at extremely high engine speeds, the change in the value of h corresponds to the minor variation in the speed is inadequate to cause a governor to operate the mechanism to provide the necessary change in the fuel supply.

As a result, this sort of governor is only suitable for engine speeds ranging from 60 to 80 rpm.

Limitations of Watt Governor

Even though it is invented to overcome the previous designs, it also consisted few limitations. The limitations of Watt Governor are

  • This Type of Governors can only be used in vertical positions.
  • In an extremely slow-speed engine, a watt governor is utilized.
  • The Sensitivity of Watt Governor decreases as speed increases.

Applications of Watt Governor

The Watt Governor applications are

  • This is employed in ships and trains to keep the engine running at a constant pace.
  • It may be utilized in AC generators to keep the power on.


Watt Governor construction looks similar to the Mechanical Governor because of its own kind. These types of governors are the first and earliest governors that almost work on all the Automobile Vehicles. As the world is turning all its technology to easy and simple; we can see lots of changes and types further. This is simple and centrifugal governor that will work purely mechanically and not any electronic or hydraulic components are involved.

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