Important terminology of governors

Prepared By-Narendra Kumar Patel

Assistant ProfessorDepartment Of Mechanical Engineering

Dr. C.V. Raman Institute Of Science & Technology, Bilaspur (C.G.)

• The function of a governor is to maintain the speed of an engine within specified limits whenever there is a variation of load.

• If the load on the shaft increases, the speed of the engine decreases unless the supply of the fuel is increased by opening the throttle valve.

• If the load on the shaft If the load on the shaft increases, the speed of the engine decreases, the speed of the engine increases unless the fuel supply is decreased by closing the valve sufficiently to slow the engine to its original speed.

• The throttle valve is operated by the governor through a mechanism for the purpose.

Governors can be broadly classified into two types:1 Centrifugal governors2 Inertia governors

Centrifugal governors

Pendulum type Loaded type Watt governor

Classification of Governor

Loaded type

Dead weight governors Spring controlled governors

Porter governor Proell governor

Hartnellgovernor

Hartung governor

Wilson-hartnell governor

Pickeringgovernor

• In watt governor• The height of a watt governor is inversely proportional to the

square of the speed. • h = mm• The following table shows the height h with the variation in

speed:

N(rpm) 50 100 150 200 300 400

h(mm) 358 89.5 39.8 22.4 9.9 5.6

This shows that in this type of governor, the movement of the sleeve is very less at high speeds and thus is unsuitable for these speeds. However, this drawback has been overcome by loading the governor with a dead weight or by means of a spring.

• In porter governor• For the given value of h, the governor is insensitive between

two values of angular velocity by Equation.• N2 = 895/h ×((m+M)/m)

• Where, M = mass of the sleeve• m = mass of each ball

• In proell governor• In this type, the two balls are fixed on the upward extension of

the lower links which are in the form of bent links.• N2 = 895/h × a/e × ((m+M)/m)

• A pickering governor is used in gramophones to adjust the speed of the turn table.

• A governor is said to be sensitive when it readily responds to a small change of speed. The movement of the sleeve for a fractional change of speed is the measure of sensitivity.

• Sensitiveness =

• Hunting is the process of continuous fluctuating of sleeve for longer periods whenever there is change in speed. This happens if the governor is too sensitive.

• A governor with a zero speed range is known as an isochronous governor. This means that for all positions of the sleeve or the balls, the governor has the same equilibrium speed.

• The power of a governor is the work done at the sleeve for a given percentage change of speed, i.e., it is the product of the effort and the displacement of the sleeve.

• The effort of the governor is the mean force acting on the sleeve to raise or lower it for a given change of speed.