1. Reg.No.
MANIPAL INSTITUTE OF TECHNOLOGY
(A Constituent Institute of Manipal University, Manipal)
V SEM B. E. (MECHANICAL ENGG.) DEGREE END SEMESTER (MAKE UP)
EXAMINATIONS DECEMBER – 2010
SUBJECT: MECHANICAL DESIGN - II (MEE-303)
(REVISED CREDIT SYSTEM)
Time: 3 Hours.
(29/12/2010)
MAX.MARKS: 50
 Answer ANY FIVE FULL questions.
 Missing data, if any may be suitably assumed.
 Use of Design Data Hand Book and non-programmable calculators are allowed. 
1.A
A machine weighing 500 kN is mounted on 10 springs in order to protect the (07)
building from vibrations. The section of the spring wire is rectangle with side
ratio 1.6. Each spring has four active turns and the spring index is 6.
Determine
i.
Section of the spring so that longer side is parallel to the axis of the
spring.
ii.
Deflection of the spring
iii.
Shear stress induced if the shorter side is parallel to the spring axis.
The allowable shear stress is 300 MPa and the modulus of elasticity
is 82.7 GPa.
1.B
Derive an expression for the deflection of helical spring from first principles.
(03)
2.A
State any 2 assumptions for deriving Lewis Equation.
(02)
2.B
Design and specify a spur gear pair driven by a 20 kW motor running at (08)
1440 rpm with a gear ratio of 4:1.The gears are 20° full depth involute. Both
the gears are of heat treated cast steel. The operation is with medium shock
for 8 to 10 hours/day. Check for wear load.
3.
A pair of Miter bevel gears is to transmit 7.5 kW at 1000 rpm. The teeth are (10)
200 stub and the number of teeth on pinion is 20. The teeth are generated
teeth. Both the pinion and gear are made of 0.20%C untreated cast steel.
Take service factor as 1.5.
i.
Determine the face width and the required module from standpoint of
strength.
ii.
Check the design from the standpoint of dynamic and wear load.
(MEE-303)
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2. 4.A
In a horizontal open belt drive for a centrifugal blower, the blower is belt (08)
driven at 600 rpm by a 15 kW, 1800 rpm electric motor. The center distance
is twice the diameter of the larger pulley. The density and Maximum
allowable stress of the belt material are1500 kg/m3 and 4 MPa respectively.
Co-efficient of friction for motor pulley and blower pulley are 0.5 and 0.4
respectively. The peripheral velocity of the belt is 2o m/s. Determine the
following
i) Pulley diameter
ii) Belt length
iii) Cross sectional area of the belt
iv) Width of the belt if thickness of the belt is 5 mm
4.B
What is “Chordal action” in chain - on - sprocket drives?
5A.
A differential band as shown in fig. 5A operates on a sheave of 420 mm (05)
diameter and rotates at 5 rps. The brake has to absorb 21 kW. Coefficient
of friction is 0.25. Determine the force F required to set the brake and What
is the width of 2 mm thick band if the tensile stress in band is not to exceed
60 MPa?
5B.
A 20 mm 8 x 19 steel wire rope is used with a hoisting drum of 1m diameter (05)
to lift a load of 20 kN. The depth of the mine is 0.8 km and the acceleration
is 3 m/s2. Determine the number of ropes required using a factor of safety 5.
Neglect the tackle weight. Take ultimate strength as 431.3 d2.
6.A
A journal bearing is to be designed for the main bearing of a four-stroke (05)
petrol engine to sustain a load of 50 kN for the shaft diameter of 50 mm.
The engine runs at 1500 rpm. Determine
i) The length of the bearing.
ii) The viscosity of the oil to be used as lubricant and hence suggest
suitable oil.
iii) Coefficient of friction and
iv) The heat generated.
6.B
Select a suitable ball bearing for the spindle of a drilling machine rotating at (05)
1200 rpm. The bearing is subjected to a radial load of 3000 N and a thrust
load of 2000 N. The machine is to work for 8 hrs/day for a service life of 5 ½
years. Based on strength, the minimum diameter of spindle is 50 mm.
(02)
Fig. 5A
All dimensions are in mm
(MEE-303)
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