# Machine Dynamics Questions and Answers – Pickering Governor

This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses on “Pickering Governor”.

1. For driving a gramophone, which of the following governor is used?
a) Watt governor
b) Hartnell governor
c) Porter governor
d) Pickering governor

Explanation: For driving a gramophone a Pickering governor is used. It consists of three straight leaf springs arranged at equal angular intervals round the spindle. Its speed is controlled by dissipating excess kinetic energy.

2. The weights move inwards and the springs bend as they rotate about the spindle axis with increasing speed.
a) True
b) False

Explanation: For a Pickering governor, the weights move outwards and the springs bend as they rotate about the spindle axis with increasing speed. Hence, the given statement is false.

3. A Pickering governor is driving a gramophone. Each disc attached to the centre of a leaf spring has a mass of 20 g. The width of each spring is 5 mm and thickness of 0.125 mm. The effective length of each spring is 40 mm. The distance from the spindle axis to the centre of gravity of the mass when the governor is at rest, is 10 mm. Find the speed of the governor in rpm when the sleeve has risen to a height of 0.8 mm. (E = 210kN/mm2)
a) 25.5
b) 2.43
c) 51.0
d) 12.25

Explanation: I = bt3/12
=0.0008mm2
Length between fixed ends (L = 40-0.8 mm)
Calculating delta from central deflection will give
δ = 3.65 mm
3.65=0.51ω2

4. A Pickering governor is driving a gramophone. Each disc attached to the centre of a leaf spring has a mass of 20 g. The width of each spring is 5 mm and thickness of 0.125 mm. The effective length of each spring is 40 mm. The distance from the spindle axis to the centre of gravity of the mass when the governor is at rest, is 10 mm, find the speed of the turntable in rpm if ratio of the governor speed to the turntable speed is 10.5.
a) 25.5
b) 2.43
c) 51.0
d) 12.25

Explanation: I = bt3/12
= 0.0008 (mm2)2
Length between fixed ends (L = 40-0.8 mm)
Calculating delta from central deflection will give
δ = 3.65 mm
3.65=0.51ω2
N = 25.5 rpm
N1 = 2.43 rpm.

5. From the following data calculate the speed of governor in rpm.
Dimensions of spring = 6mm wide, 0.12 mm thick and length = 48 mm
mass attached to each leaf at centre = 25g
Distance between spindle axis and C.O.M when the governor is at rest = 8mm
Sleeve lift = 0.6mm
E = 200 GN/mm2
a) 575
b) 625
c) 600
d) 550

Explanation: I = bt3/12
= 0.864×10-15 (m2)2
δ = 0.003464 m
= Fl3/192EI
N=575 rpm.

6. From the data given:
Dimensions of spring = 6mm wide, 0.12 mm thick and length = 48 mm
mass attached to each leaf at centre = 25g
Distance between spindle axis and C.O.M when the governor is at rest = 8mm
Sleeve lift = 0.6mm
E= 200 GN/mm2
Find the speed of the turntable in rpm if ratio of the governor speed to the turntable speed is 10.
a) 57.5
b) 62.5
c) 60
d) 55

Explanation: I = bt3/12
= 0.864×10-15 (m2)2
δ = 0.003464 m
= Fl3/192EI
N=575 rpm
N1= N/10
= 57.5 rpm.

7. In case of pickering governor, the central load is_______
a) Centripetal force
b) Centrifugal force
c) Torque
d) Normal reaction

Explanation: W = FC = m.ω2 (a + δ), this is the expression of the central load, hence the central load is the centrifugal force.

8. Porter governor is used to vary the speed of the turntable in a gramophone.
a) True
b) False

Explanation: Pickering governor is used to vary the speed of the turntable in a gramophone. Porter governor is used to regulate the speed of the engine.

9. Which of the following part of the spring is attached to the sleeve?
a) Upper end
b) Lower end
c) Middle part
d) At a height 34 of total length

Explanation: The working of a Pickering governor includes: attachment of the lower end of the spring to the sleeve which is free to slide on the spindle. The spindle runs in a bearing at each end and is driven through gearing by the motor.

Sanfoundry Global Education & Learning Series – Machine Dynamics.

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