Machine Design Past Papers and important Questions

By: Prof. Fazal Rehman Shamil

Machine Design Past Papers 1

Paper: Machine Design

Time Allowed: 3 hours

Examination:  

Total Marks:    70, Passing Marks (35)

Q.1      True/False                                                                                                                                Marks (14)

  1. The loss of energy in any one form is always accompanied by an equivalent increase in another form.
  2. Stiffness is It is the ability of a material to resist deformation under stress.
  3. The ability to withstand contraction stresses of some members of the casting may be improved by providing the curved shapes e.g., the arms of pulleys and wheels.
  4. A tolerance of ± 1.6 mm on small castings (below 300 mm) should be provided. In case more dimensional accuracy is desired, a tolerance of ± 0.8 mm may be provided.
  5. A basic hole is one whose lower deviation is zero.
  6. The algebraic difference between the maximum limit and the basic size is called upper deviation.
  7. Factor of Safety is the ratio of Maximum Stress to the Working Stress

Q.2      The dimensions of the mating parts, according to basic hole system, are given as follows :

Hole : 25.00 mm Shaft : 24.97 mm
           25.02 mm             24.95 mm

Find the hole tolerance, shaft tolerance and allowance.                                                        Marks (14)

Q.3      Calculate the force required to punch a circular blank of 60 mm diameter in a plate of 5 mm thick.

The ultimate shear stress of the plate is 350 N/mm2                                                               Marks (14)

Q.4        What is the difference between modulus of elasticity and modulus of rigidity?                 Marks (14)

Q.5      Two machine parts are fastened together tightly by means of a 24 mm tap bolt. If the load tending to separate these parts is neglected, find the stress that is set up in the bolt by the initial tightening.                                                                                                                     Marks (14)

Q.6    What is a cotter joint? Explain with the help of a neat sketch, how a cotter joint is made?       Marks (14)                                                                                                             

Q.7        Describe, with the help of neat sketches, the types of various shaft couplings mentioning the uses of
each type.                                                                                                                                     Marks (14)

Q.8      Write a short note on any two of the following:                                                                       Marks (7,7)

  1.   Single Start and Double Start Threads
  2.   Flange Couplings
  3.   Standard Sizes of Transmission Shafts

Machine Design Important Questions from Past Papers 2

Paper: Machine Design

Time Allowed: 3 hours

Examination:  

Total Marks:    70, Passing Marks (35)

Q.1 True/False Marks (14)

a. The railway carriage coupling has buttress threads.
The mass density of the material is the mass per unit volume.
b. Torque is directly proportional to the rate of change of angular momentum.
c. The energy stored in a body when strained within elastic limit is known as strain energy.
d. While designing a screw in a screw jack against buckling failure, the end conditions for the screw are
taken as one end fixed and other end free.
e. The factor of safety for steel and for steady load is 4.
f. Multiple threads are used to secure high efficiency.
h. The ratio of linear stress to linear strain is called Modulus of elasticity

 

Q.2 Describe the procedure for finding out the stresses in a composite bar. Marks (14)

Q.3 A steel shaft 50 mm diameter and 500 mm long is subjected to a twisting moment of 1100 N-m,
The total angle of twist being 0.6°. Find the maximum shearing stress developed in the shaft
and modulus of rigidity Marks (14)

Q.4 Write the relations used for maximum stress when a machine member is subjected to tensile or
compressive stresses along with shearing stresses. Marks (14)

Q.5 What do you understand by the single start and double start threads ? Marks (14)

Q.6 Enumerate the different types of riveted joints and rivets Marks (14)
Q.7 What is a cotter joint? Explain with the help of a neat sketch, how a cotter joint is made? Marks (14)

Q.8 Write short note on any two of the following: Marks (7,7)
a. Parallel fillet welded joints
b. Factor of Safety
c. Stress & Strain Diagram for ductile materials

Machine Design Guess Papers 3

Paper: Machine Design

Time Allowed: 3 hours

Examination:  

Total Marks:    70, Passing Marks (35)

Q.1 True/False Marks (14)
a. The power transmitted by means of a belt depends upon velocity of the belt and tension under which
the belt is placed on the pulleys
b. A V-belt designated by A-914-50 denotes a standard belt.
c. When two concentric coil springs made of the same material, having same length and compressed
equally by an axial load, the load shared by the two springs will be directly proportional to the
square of the diameters of the wires of the two springs.
d. The property of a bearing material which has the ability to accommodate small particles of dust,
grit etc, without scoring the material of the journal, is called embed ability
e. In a leaf springs the longest leaf is known as master leaf
f. The taper on a rectangular sunk key is 1 in 100
g. Oldham coupling is used to connect two shafts which have lateral misalignment

Q.2 For bevel gears, define the following: Marks (14)
(i) Cone distance;
(ii) Pitch angle;
(iii) Face angle;
(iv) Root angle;

Q.3 An engine running at 300 r.p.m. drives a line shaft by means of a belt. The engine pulley is
1500 mm diameter and the pulley on the line shaft is 900 mm. A 1800 mm diameter pulley
on the line shaft drives a 300 mm diameter pulley keyed to a dynamo shaft.
Fine the speed of dynamo shaft, when
1. there is no slip, and
2. there is a slip of 3% at each drive. Marks (14)

Q.4 Design a roller chain to transmit power from a 20 kW motor to a reciprocating pump. The pump is
To operate continuously 24 hours per day. The speed of the motor is 600 r.p.m. and that of the pump
Is 200 r.p.m. Find:
1. Number of teeth on each sprocket;
2. Pitch and width of the chain. Marks (14)

Q.5 A chain wrapped round the sprocket is shown in Figure. Since the links of the chain are rigid,
therefore pitch of the chain does not lie on the arc of the pitch circle. The pitch length becomes a
chord. Consider one pitch length AB of the chain subtending an angle at the centre of sprocket or
pitch circle and find and expression for calculating pitch of the chain and sprocket outside diameter
(Do) for satisfactory operation. Marks (14)

Machine Design Past Papers 4

Paper: Machine Design

Time Allowed: 3 hours

Examination:  

Total Marks:    70, Passing Marks (35)

Q.1 True/False Marks (14)

a. The gears are termed as medium velocity gears, if their peripheral velocity is 3 – 15 m/sec
b. The helix angle for double helical gears may be made up to 45°
c. The included angle for the V-belt is usually 30° – 40°.
d. The face angle of a bevel gear is equal to pitch angle + addendum angle
e. The rolling contact bearings are known as antifrictional bearing.
f. When the length of the journal is equal to the diameter of the journal, then the bearing is said to
be a square bearing.
g. The taper on cotter varies from 1 in 48 to 1 in 24

 

Q.2 Mention four important types of gears and discuss their applications, the materials used
for them and their construction. Marks (14)

Q.3 A pair of helical gears are to transmit 15 kW. The teeth are 20° stub in diametral plane and
have a helix angle of 45°. The pinion runs at 10 000 r.p.m. and has 80 mm pitch diameter.
The gear has 320 mm pitch diameter. If the gears are made of cast steel having allowable static
strength of 100 MPa; determine a suitable module and face width from static strength
considerations and check the gears for wear, given σes = 618 MPa. Marks (14)

Q.4 Sketch neatly the working drawing of bevel gears in mesh. Marks (14)
Q.5 Write short note on classifications and different types of antifriction bearings. Marks (14)

Q.6 An engine running at 150 r.p.m. drives a line shaft by means of a belt. The engine pulley is 750 mm
diameter and the pulley on the line shaft is 450 mm. A 900 mm diameter pulley on the line shaft drives
a 150 mm diameter pulley keyed to a dynamo shaft. Fine the speed of dynamo shaft, when
1. there is no slip, and
2. there is a slip of 2% at each drive. Marks (14)
Q.7 What are the applications of a cottered joint ? Marks (14)

Q.8 Write short note on any two of the following: Marks (7,7)
a. Types of Springs.
b. Failure analysis of rivet joints
c. Advantages of V belts

Prof. Fazal Rehman Shamil