Exam. 2B 
Machine Elements Design 

Student Name: 
Student No. 
1) A Define the following (3 only +): 

a Spring index:
b
Coil spring mean diameter:
c Wahl factor:
d Spring maximum deflection:
1) B Write the types of springs:

Type of spring 
Uses 

1 



2 



3 



1) C If k_{1 }= 700 N/mm, k_{2} = 400
N/mm, k_{3} = 200 N/mm
+ i Which one will have more defliction under the same load?
ii Find the equevlant spring rate in the figure shown:
iii What is the deflection of the springs in the figure under a load of 1100 N
2) A helical compression spring has a mean spring diameter D of 120 mm.
i If the allowable shear stress due to torsion only on the spring is 300 MPa, when a load P_{1} = 4000 N is applied to it. Find the spring wire diameter d.
+ ii Find the spring index C, and the Wahl factor K_{w}, and solid length L_{s} if the total number of turns is 10, and the ends are plain.
iii Find the total stress due to a maximum load P_{2 }of 5000 N for the same spring.
iv Check the stress using the nomogram, for case iii.
4) The 4,000 N force is applied to M8 setscrew. If the required safety factor is 2, decide on the suitable material for the setscrew.