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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER-V EXAMINATION WINTER 2018
Subject Code:X51903 Date: 20/11/2018
Subject Name: Machine Design
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Explain Goodman's and Soderberg's diagram with neat sketches.
07

Write a brief note on the design of castings.
07
Q.2

Prove that in a spring, using two concentric coil springs made of same material, having same length and compressed equally by an axial load, the loads shared by the two springs are directly proportional to the square of the diameters of the wires of the two springs.
07

A concentric spring for an engine valve is to exert a maximum force of 5000 N under an axial deflection of 40 mm. Both the springs have same free length, same solid length and are subjected to equal maximum shear stress of 850 MPa. The spring index for both the springs is 6.
Find: the load shared by each spring, the main dimensions of both the springs, and the number of active coils in each spring.
Assume G 80 kN/mm2 and diametral clearance to be equal to the difference between the wire diameters. Also Assume square and ground ends for the spring.
07
OR

Write a note on the influence of various factors of the endurance limit of a ductile material.
07
Q.3

Derive the equation for length of cross belt drive.
07

Derive a formula for the thickness of a thin spherical tank subjected to an internal fluid pressure.
07
OR
Q.3

List advantages and disadvantages of chain drive over belt drive.
07

Distinguish between circumferential stress and longitudinal stress in a cylindrical shell, when subjected to internal pressure.
07
Q.4

Under what circumstances a fibre rope and a wire rope is used? What are the advantages of a wire rope over fibre rope?
07

What are the advantages and disadvantages of V-belt drive over flat belt drive?
07
OR
Q.4

Explain the performance of a hydrodynamic bearing with the curve of versus Z.N p.
07

Explain with sketches the working of different types of thrust bearing.
07
Q.5

Establish a formula for the frictional torque transmitted by a cone clutch.
07
2

A simple band brake operates on a drum of 600 mm in diameter that is running at 200 r.p.m. The coefficient of friction is 0.25. The brake band has a contact of 270°, one end is fastened to a fixed pin and the other end to the brake arm 125 mm from the fixed pin. The straight brake arm is 750 mm long and placed perpendicular to the diameter that bisects the angle of contact.
What is the pull necessary on the end of the brake arm to stop the wheel if 35 kW is being absorbed? What is the direction for this minimum pull?
07
OR
Q.5

Explain the design procedure for a single plate clutch considering uniform pressure theory.
07

How does the function of a brake differ from that of a clutch? Also describe with the help of a neat sketch the principle of operation of an internal expanding shoe brake.
07