III B.Tech.
I Sem– 2020-21; Mid Exam-II Branch : ME ; Max Marks: 15 M ; Duration: 90 Min
Course Name: DYNAMICS OF MACHINERY Course Code: 19A03505
Answer any one full question from each Unit. Each question carries 5 marks
S.No Question Marks CO Cognitive
Level
1 Draw a neat sketch of Proell Governor? Derive Spring Speed of a 5 3 V
proell Governor?
OR
All the arms of a Porter governor are 178 mm long and are
2 hinged at a distance of 38 mm from the axis of rotation. The 5 3 V
mass of each ball is 1.15 kg and mass of the sleeve is 20 kg. The
governor sleeve begins to rise at 280 r.p.m. when the links are at
an angle of 30° to the vertical. Assuming the friction force to be
constant, determine the minimum and maximum speed of
rotation when the inclination of the arms to the vertical is 45°?
3 Four masses m1, m2, m3 and m4 are 200 kg, 300 kg, 240 kg and 5 4 V
260 kg respectively. The corresponding radii of rotation are 0.2
m, 0.15 m, 0.25 m and 0.3 m respectively, and the angles
between successive masses are 45°, 75° and 135°. Determine the
position and magnitude of the balance mass required, if its radius
of rotation is 0.2 m?
OR
Explain the Concept of Direct and Reverse Crank for Balancing
4 of Radial engines? 5 4 II
5 A vertical shaft of 5 mm diameter is 200 mm long and is supported in 5 5 V
long bearings at its ends. A disc of mass 50 kg is attached to the centre
of the shaft. Neglecting any increase in stiffness due to the attachment
of the disc to the shaft, find the critical speed of rotation and the
maximum bending stress when the shaft is rotating at 75% of the
critical speed. The centre of the disc is 0.25 mm from the geometric
axis of the shaft. E = 200 GN/m2 ?
OR
Explain the terms of Vibration Isolation and Transmissibility?
6 5 5 II
III B.Tech. I Sem– 2020-21; Mid Exam-II Branch : ME ; Max Marks: 15 M ; Duration: 90 Min
Course Name: DYNAMICS OF MACHINERY Course Code: 19A03505
Answer any one full question from each Unit. Each question carries 5 marks
S.No Question Marks CO Cognitive
Level
1 Each art of a Porter governor is 200 mm long and is pivoted on 5 3 V
the axis of the governor. The radii of rotation of the balls at the
minimum and the maximum speeds are 120 mm and 160 mm
respectively. The mass of the sleeve is 24 kg and each ball is 4
kg. Find the range of speed of the governor. Also determine the
range of speed if the friction at the sleeve is 18 N?
OR
In a Hartnell governor, the radius of rotation of the balls is 60 mm at
2 the minimum speed of 240 rpm. The length of the ball arm is 130 mm 5 3 V
and the sleeve arm is 80 mm. The mass of each ball is 3 kg and the
sleeve is 4 kg. The stiffness of the spring is 20 N/mm. Determine the
following: (i) Speed when the sleeve is lifted by 50 mm. (ii) Initial
compression of the spring. (iii) Governor effort. (iv) Power?
A, B, C and D are four masses carried by a rotating shaft at
3 radii 100, 125, 200 and 150 mm respectively. The planes in 5 4 V
which the masses revolve are spaced 600 mm apart and the
mass of B, C and D are 10 kg, 5 kg, and 4 kg respectively. Find
the required mass A and the relative angular settings of the four
masses so that the shaft shall be in complete balance?
OR
The firing order in a 6 cylinder vertical four stroke in-line engine is 1-4-
4 2-6-3-5. The piston stroke is 100 mm and the length of each 5 4 V
connecting rod is 200 mm. The pitch distances between the cylinder
centre lines are 100 mm, 100 mm, 150 mm, 100 mm, and 100 mm
respectively. The reciprocating mass per cylinder is 1 kg and the
engine runs at 3000 r.p.m. Determine the out-of-balance primary and
secondary forces and couples on this engine, taking a plane midway
between the cylinder 3 and 4 as the reference plane?
5 A shaft 50 mm diameter and 3 metres long is simply supported at the 5 5 V
ends and carries three loads of 1000 N, 1500 N and 750 N at 1 m, 2 m
and 2.5 m from the left support. The Young's modulus for shaft
material is 200 GN/m2 . Find the frequency of transverse vibration?
OR
Derive Dunkerley’s method to find the natural frequency of a
6 shaft carrying several loads? 5 5 V
III B.Tech. I Sem– 2020-21; Mid Exam-II Branch : ME ; Max Marks: 15 M ; Duration: 90 Min
Course Name: DYNAMICS OF MACHINERY Course Code: 19A03505
Answer any one full question from each Unit. Each question carries 5 marks
S.No Question Marks CO Cognitive
Level
Explain the following qualities of the governor:
1 (a) Sensitiveness. (b) Stability. (c) Effort and power 5 3 II
OR
In a Porter governor all the arms are 300 mm long. Upper and lower
2 arms are pivoted on the axis of rotation. Central mass is 15 kg. Mass 5 3 V
of each ball is 5 kg. Force of friction is 30 N and the extreme radii of
rotation are 200 mm and 250 mm. Determine the range of speed: (i)
Without considering friction. (ii) Considering friction?
3 A shaft is rotating at a uniform angular speed. Four masses M1, M2, 5 4 V
and M3 and M4 of magnitudes 300 kg, 450 kg, 360 kg, 390 kg
respectively are attached rigidly to the shaft. The masses are rotating
in the same plane. The corresponding radii of rotation are 200 mm,
150 mm, and 250 mm and 300 mm respectively. The angle made by
these masses with horizontal are 0°, 45°, 120°and 255° respectively.
Find: (i) The magnitude of balancing mass. (ii) The position of
balancing mass if its radius of rotation is 200 mm?
OR
A four cylinder vertical engine has cranks 150 mm long. The planes of
4 rotation of the first, second and fourth cranks are 400 mm, 200 mm 5 4 V
and 200 mm respectively from the third crank and their reciprocating
masses are 50 kg, 60 kg and 50 kg respectively. Find the mass of the
reciprocating parts for the third cylinder and the relative angular
positions of the cranks in order that the engine may be in complete
primary balance.?
5 Calculate the whirling speed of a shaft 20 mm diameter and 0.6 m 5 5 V
long carrying a mass of 1 kg at its mid-point. The density of the shaft
material is 40 kg/m 3, and Young’s modulus is 200 GN/m2 . Assume the
shaft to be freely supported.?
OR
Derive the method of finding the normal frequency of torsional
6 vibrations for a three rotor system? 5 5 V
III B.Tech. I Sem– 2020-21; Mid Exam-II Branch : ME ; Max Marks: 15 M ; Duration: 90 Min
Course Name: DYNAMICS OF MACHINERY Course Code: 19A03505
Answer any one full question from each Unit. Each question carries 5 marks
S.No Question Marks CO Cognitive
Level
Explain the following qualities of the governor:
1 (a) Sensitiveness. (b) Stability. (c) Effort and power 5 3 II
OR
A Proell governor has all four arms of length 305 mm. The upper arms
2 are pivoted on the axis of rotation and the lower arms are attached to 5 3 V
a sleeve at a distance of 38 mm from the axis. The mass of each ball is
4.8 kg and are attached to the extension of the lower arms which are
102 mm long. The mass on the sleeve is 45 kg. The minimum and
maximum radii of governor are 165 mm and 216 mm. Assuming that
the extensions of the lower arms are parallel to the governor axis at
the minimum radius, find the corresponding equilibrium speeds.
3 A, B, C and D are four masses carried by a rotating shaft at radii 100, 5 4 V
125, 200 and 150 mm respectively. The planes in which the masses
revolve are spaced 600 mm apart and the mass of B, C and D are 10
kg, 5 kg, and 4 kg respectively. Find the required mass A and the
relative angular settings of the four masses so that the shaft shall be in
complete balance?
OR
Explain Swaying couple and Hammer blow?
4 5 4 II
5 The mass of a single degree damped vibrating system is 7.5 kg and 5 5 V
makes 24 free oscillations in 14 seconds when disturbed from its
equilibrium position. The amplitude of vibration reduces to 0.25 of its
initial value after five oscillations. Determine : 1. stiffness of the
spring, 2. logarithmic decrement, and 3. damping factor, i.e. the ratio
of the system damping to critical damping?
OR
Derive the method of finding the normal frequency of torsional
6 vibrations for a two rotor system? 5 5 V
