### THEORY OF MACHINES DIPLOMA 4TH SEMESTER MECHANICAL ENGINEERING

Model Question Paper

Mechanical Engineering Board

Fourth Semester

2010-2011

THEORY OF MACHINES

Max.Marks:100                                                                                                  Time: 3Hrs

Note : 1. Question No.1 is compulsory

2. Answer any two full questions from each of the remaining sections

3.  Any missing data may be suitably assumed

1.    a) Fill in the blanks with appropriate word /words                                            5x1=5

i) Hydraulic press is a __________ link.

ii) Type writer constitutes a __________

iii) The size of the cam depends on ______________ circle.

iv) The product of diametrical pitch and circular pitch is equal to________

v)  The brakes are commonly used in cars___________

b) Describe with a neat sketch single plate clutch .                                                    5

SECTION-I

2.   a) Define Theory of machines .                                                                                   2

b) Explain three types of constrained motions.                                                           6

c) Describe with a neat sketch , the crank and slotted lever quick return motion

mechanism.                                                                                                            7

3.   a) Explain with a neat sketch ,Scotch yoke mechanism .                                            6

b) What is pivot bearing ? Give its applications.                                                        4

c) A conical pivot bearing supports a vertical shaft of 200 mm diameter. It is

subjected to a load of 30 KN. The angle of the cone is 120 degree and the

co-efficient of friction is 0.025 .Find the power lost in friction, when the speed

is 140 rpm, assuming uniform pressure condition.                                                  5

4.  a) What is the function of clutch ?                                                                                2

b) Differentiate between brake and clutch .                                                                  5

c) A multiple disc clutch has five plates having four pairs of active friction

surfaces . If the intensity of pressure is not to exceed 0.127 N / sq. mm ,find the

Power transmitted at 500 rpm .The outer and inner radii of friction surfaces

Are 125 mm and 75 mm respectively. Assume uniform wear.                               8

SECTION-II

5.  a) List the types of belt drives .                                                                                     3

b) Explain what do you understand by “Initial Tension in a belt” .                              2

c) An open belt running over two pulleys 240 mm and 600 mm diameters connects

two parallel shafts 3 m apart and transmit 4 kw from the smaller pulley that

rotatates at 300rpm .The co-efficient of friction between the belt and pulley is 0.3 and the safe working. Tension is 10 N /mm width. Determine the

i) minimum width of the belt ,

ii) initial tension and

iii) length of belt required .                                                                                  10

6  a) List the classification of toothed wheels.                                                                   2

b) Explain with a neat sketch ,the compound gear train .                                              7

c)  Draw the nature of displacement, velocity and  acceleration diagrams ,when the

follower moves with SHM .                                                                                      6

7  a) Define the following terms related to radial disc cam .

i) Base circle  ii) Prime circle & iii) Pitch circle                                                         3

b) Why the Roller follower is preferred over the knife edge follower.                           2

c) Draw the profile of the cam with knife edged follower is raised through a distance

of 30 mm in 1 / 3 rd of revolution of the cam and is lowered in 1 / 3 rd revolution

with equal intervals between these movements .The follower must move with the

following data

Out stroke-----SHM

Return stroke---Constant acceleration. 80 degree & constant retardation. 40 degree .       10

SECTION-III

8.  a) What is the function of a Governor ?                                                                         2

b) Define the following terms used in Governors

i) Height of the governor

ii) Mean equilibrium speed

iii) Sleeve lift                                                                                                                5

c) Explain with a neat sketch ,the working  of Centrifugal governor.                            8

9  a) Explain the different types of Free vibrations with sketches .                                   10

b) What do you mean by balancing ?                                                                               2

c) Explain the balancing of single rotating mass by a single mass in the same plane     3

10 a) Briefly explain static balancing .                                                                                3

b) A shat carries two rotating masses 5 kg and 2 kg attached at radii 300 mm and

600 mm respectively from axis of rotation .The included angle between two radii

is 60 degree ,find the angular position and radius of rotation of balance mass if its

mass is 3 kg . If no balance mass is used ,what is the out of balance force on shaft

bearing at 400 rpm.                                                                                                     4

c) Four masses m1,m2 ,m3 & m4 are 200 kg ,300 kg ,240 kg &260 kg respectively.

The corresponding radii of rotation are 200 mm , 150 mm ,250 mm ,& 300 mm

respectively and the angles between successive masses are 45 degree ,75 degree

& 135 degree .Find the position and magnitude of the balance mass required by

graphical method , if its radius of rotation is 200 mm .