Governors - Online Article

Introduction

The function of governor is to regulate the mean speed of an engine, when there are variations in load. For example: when the load of an engine increases then its speed decreases, therefore it becomes necessary to increase the supply of working fluid. It means when the load of an engine decreases its speed increases and thus less working fluid is required. For that purpose we use the governor, the governor automatically controls the supply of working fluid to the engine with varying load conditions and try to keeps the mean speed within certain limits.

NOTE: The function of flywheel in an engine is entirely different from that of a governor. It controls the speed variation caused by the fluctuations of the engine turning moment during each cycle of operation. It does not control the speed variation caused by the varying load.

Terms used in Governors

Height of the Governors

It is the vertical distance from the centre of the ball to a point where the axis of the arms intersects on the spindle axis.

Equilibrium speed

It is the speed at which the governor balls, arms are in complete equilibrium and sleeve does not tend to move upward or downward.

Mean equilibrium speed

It is the speed at the mean position of balls or sleeve.

Maximum and minimum equilibrium speed

The speed at the maximum and minimum radius of rotation of the balls, without tending to move either ways are known as maximum and minimum equilibrium speed.

Sleeve lift

It is the vertical distance which the sleeve travels due to change in equilibrium speed.

Sensitiveness of Governor

It is the ratio of the difference between the maximum and minimum equilibrium speeds to the mean equilibrium speed. If N1 =minimum equilibrium speed If N2=maximum equilibrium speed N (mean speed) = ( N1+N2 ) / 2 Sensitiveness of the governor = 2 ( N2 - N1 ) / ( N1 + N2 ).

Types of Governor

  • Centrifugal Governors
    • Pendulum type-watt governor
    • Loaded type
      • Dead weight governors: these are two types
        • Porter Governor
        • Proell Governor
      • Spring controlled governors: these are mainly four types
        • Hartnell Governor
        • Hartung Governer
    • Wilson-Hartnell Governor
    • Pickering Governor
  • Inertia Governors

Centrifugal Governor

The centrifugal governors based on the balancing of centrifugal force on the rotating balls by an equal and opposite force, known as the controlling force. It consists 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 ends of the arms are pivoted to the pindle.

Image1

Watt Governor

The simplest form of centrifugal governor is watt governor. The arms of the governor may be connected to the spindle by two ways:

  • Pivot may be on the spindle axis.

Image2

  • Pivot may be offset from the spindle axis but arms intersect at o.

Porter Governor

This governor is the modification of watt governor, with central load attached to the sleeve. The load moves up and down the spindle axis. This load is responsible forballs to rise to any pre determined level.

Image3

Proell Governor

In proell governor balls are fixed.

Hartnell Governor

It is a spring loaded governor. It consists of two bell crank lever pivoted at the frame. The frame is attached to the governor spindle and therefore rotates with it. A helical spring in compression provided equal downward force on the two rollers through a collar on the sleeve.

Wilson Hartnell Governor

Image4

In this type of governor balls are connected by a spring in tension. A auxiliary spring is attached to the sleeve mechanism through a lever by means of which the equilibrium speed for a given radius may be adjusted. The main spring may be considered of two equal parts each belonging to both the balls.

Pickering Governor

It is mostly used for driving gramophone. It consists of three straight leaf springs arranged at equal angular intervals round the spindle. Each springs carries a weight at the centre.

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Comments

shylesh babu on 2011-09-03 05:53:25 wrote,

main application for governor is missing here.

jagan jagan on 2012-01-01 12:40:07 wrote,

purpose of governor is missing here and use of governor

jagan jagan on 2012-01-01 12:40:11 wrote,

purpose of governor is missing here and use of governor