MECHANICAL ENGINEERING DEPARTMENT, OITM

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Semester : 6th

Subject: MD-II

Paper : ME- 310E

Unit 1

Q.1(a) Explain the different causes of gear tooth failure and suggest possible remedies to avoid such

failure. (6)

(b) A helical gear speed reducer is to be used with a 2000 rpm electric motor and 500rpm load for

moderate amount of shock. The 24 tooth pinion has a normal module of a 3 mm . the face width of 40mm

,the normal pressure angle of 200 and helix angle of 23

0 (BHN 262) both the gear and pinion are made of

steel and case hardening . Estimate the power that can be transmitted by reducer .will the heat treatment

be sufficient from the wear point of view? (14) June. 07

Q.2 Determine the proper pitch ,module, face width, no. of teeth and outside of a pair of 200 in volute full

depth spur gear to transmit 112.5 Kw from a pinion running at 750 rpm to a gear running at 140 rpm . The

service is intermittent with light shock. (20) June. 07

Q. 3 (a) Define law of gearing . how are gear classified? (5)

(b) Define formative number of teeth on a helical gear. Also derive expression used to obtain its value?

(15) May. 09

Q.4 Design a pair of helical gear to transmit 30KW power at speed reduction ratio 4:1 . The input shaft

rotate at 2000rpm .Take helix and normal pressure angle equal to 250 and 20

0 ,respectively.Both pinion

and gear are made of steel. The following data is given;

Name of parts Permissible stress BHN

PINION 55MPA 340

GEAR 40MPA 300 (20) June-2010

Q.5 A pair straight bevel gear must transmit 15KW at 1250 rev/min of the 18 tooth pinion . Speed

reduction ratio is 3.5: 1 . Use 14.5 full depth teeth. Select the material to obtain a compact design.

Determine the module, the gear face,pitch diameter and pitch cone angle for both gears.(20) May.11

Q.6 Design the teeth for a pair of cast iron spur gear with cast teeth to transmit 26KW. The pinion run at

50 rev/min and the velocity ratio is to be 2.5.Decide upon a suitable grade of cast iron and find the

module,face and diameters and center distance for the gear. (20) May. 11

Q.7 Two steel bevel gear, both having a brinell hardness of 250 connect shaft at 900. The teeth are

14.5”full depth and module is 5mm. The no. of teeth on the pinion and gear are 30 and 48. The face width

is 38mm. Determine the wear load. (20) June.08

MECHANICAL ENGINEERING DEPARTMENT, OITM

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Q.8(a) Write a note on the gear housing? (10)

(b) Explain the design procedure of gear box design. (10) June.08

Unit- 2

Q. 9 An electric motor running at 1500 rpm is to transmit 11Kw to a machine tool gear box input shaft at

900rpm Approx. centre distance is 70mm. Give complete design of suitable belt and pulley drive.

(20) May2011

Q. 10 (a) What is condition of self locking in differential band brake? Why should it be avoided in speed

control brakes? (8)

(b) A cone clutch is used to connect an electric motor running at 1440 rpm with a machine that is

stationary. The machine is equivalent to a rotor of mass 150 Kg and radius of gyration as 250 mm. The

machine has to be brought to the full speed of 1440 rpm from a stationary condition in 40 sec. The semi

cone angle α is 12.50 . The mean radius of the clutch is twice the face width. The co-efficient of friction is

0.2 and normal intensity of pressure between contacting surface should not exceed 0.1 N/mm2. Calculate

the inner and outer diameter, face width of friction lining, the force required to engage the clutch.

(12) May 2011

Q. 11(a) In a plate clutch the axial force is 4500N. The inner radius of contact is 50 mm and outside

radius is 100 mm. Assuming uniform wear determine the maximum pressure, minimum pressure, average

pressure. (15)

(b) Define the clutch load characteristics? (5) June2008.

Q. 12 A belt is required to transmit 15 ?Kw from a pulley 1.2 m diameter at 300 rpm to another pulley

which runs at 500 rpm. The centre distance is 3 m . The centre line of drive makes an angle 50 0 with

horizontal. Design a suitable flat leather belt for a drive . Also design the larger pulley. (20) May 2009

Q. 13 Determine the maximum, minimum and average pressure in a plate clutch when the axial force 4

KN. The inside radius of the contact surface is 45mm and outside radius is 100mm. Assume uniform

wear. (20) May 2009

Q.14 Select a suitable chain drive to transmit 30KW from an electric motor to a line shaft. Motor shaft

diameter is 60mm,motor rpm=1200,rpm line shaft is 250,and center distance is adjustable from

600mm.Service is 10hr/day,6days per week. Good lubrication condition is expected. (20) June.10

Q.15 Design a chain drive for the following duty:

Power to be transmitted =6KW

Speed of motor shaft =1000rpm

Speed of driven shaft =500rpm

Center distance =600mm (20) June.08

MECHANICAL ENGINEERING DEPARTMENT, OITM

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Q.16 Differentiate between clutches and brakes. Name various types of clutches and brakes used in

automobiles. (10)

(b) Design a dry single plate clutch for the following data:

Power to be transmitted =15 KW

Speed = 1000rpm (10) June. 08

Unit-3

Q.17 (a) Discuss and explain the following terms; (8) June.10

1. Hydrodynamic lubrication

2. Bearing characteristics’ number

3. Sommerfield number

4. Operating pressure

(b) Select a single row deep groove ball bearing for a radial load of 5000N and an axial load of

6000N,operating at a speed of 1600 rpm for an average life of 5 years at 10 hours per day. Assume

uniform and steady load. (10) June.10

Q.18 (a) Explain what do you understand by A.M. Wahl’s factor and state its importance in the design of

helical springs. (5)

(b) Design a helical spring for loaded safety valve for the following data:

Diameter of valve seat=65mm

Operating pressure =0.7N/mm2

Max. Pressure =0.75N/mm

Max lift of valve =3.5mm

Max. allowable stress =550Mpa

Modulus of rigidty =84KN/mm2

Spring index =6

Draw a neat sketch of spring showing the main dimension. (15) June07

MECHANICAL ENGINEERING DEPARTMENT, OITM

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Q.19 Design a helical spring compression spring for a max. load 1000N for a deflection of 25 mm using

the value of spring index as 5. The max. Permissible shear stress for spring wire is 420Mpa and modulus

of rigidity is 84KN/mm2. Take Wahl’s factor:

K=

Where C= Spring index (20) May. 09

Q.20(a) Differentiate between Hydrodynamic lubrication and wedge fillet lubrication. (5)

(b) Design a journal bearing to support a load of 5000N and speed 500rpm using hardened steel journal

and bronze backed bearing. The bearing is lubricated by oil, room temp. is 250c and oil temp is 8

0c.

(15) May09

Q.21 A semi elliptical spring has 10 leaves in all, with the two full length leaves extending 625 mm.It is

62.5 mm wide and is made of strips 6mm thick. Design a helical spring, with the mean diameter of coil

100 mm, which will have approximate. The same values of induced stress and deflection for any load.

(20) June.08

Q.22 A semielliptical laminated a spring to carry load of 6000N and consist of 8 leaves 46 mm wide,2of

leaves being of full length The spring is to be made 1100 mm between the eyes and is held at center by a

70mm wide band . Assume the spring initially stressed so as to induce equal stress of 500 N/mm2

when

fully loaded. Design the spring giving:

a. Thickness of leaves

b. eye diameter

c. length of leaves

d. max. Deflection and camber

Assume E=2.1*105N/mm

2 (20) May.11

Q.22 Design a suitable journal bearing for a centrifugal pump from the following data:

Load on the bearing is = 13.5KN,Dia of journal =80mm, Speed =1440rpm, Bearing character stics no. at

the working temp.(750c)=30,Permissible bearing pressure intensity =0.7N/mm

2 and average atmospheric

temp.=300c. Calculate the cooling temperatures. if any. (20) May.11

Q.23 Design a bearing and journal to support a load of 4500N at 600rpm using a hardened steel journal

and a bronze backed Babbitt bearing. The bearing is lubricated by oil rings. Take room temp. as 210c and

oil temp. as 800c. (20) June.08

MECHANICAL ENGINEERING DEPARTMENT, OITM

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Q.24 It is required to design a helical compression spring for the valve mechanism. The axial force acting

on the spring is 300N when the valve is open and 150N when the valve is closed. The length of the spring

is 30mm when the valve is open and 35mm when the valve is closed. The spring is made of oil hardened

and tempered valve spring wire and the ultimate tensile strength is 1370N/mm2. The permissible shear

stress for spring wire should be taken as 30% of the ultimate tensile strength. The modulus of rigidity is

81370N/mm2.

The spring is to be fitted over a valve rod and the min. inside dia. Of the spring should be 20mm. Design

the spring and calculate:

Wire dia.,Mean coil dia. ,Num. of active coils ,Total number of coils, Free length of coil , Pitch of the coil

(20) June.10

Unit-4

Q.25 Design the connecting rod of an I.C. engine for the following data:

Piston dia.=0.15m

Stroke =0.215m

Length of connecting rod=0.5m

Weight of reciprocating parts= 275N

Speed=2000rpm with possible overspeed of 3000rpm

Compression ratio=5:1

Probable max. explosion pressure=3.5Mpa (20) June08

Q.26 Design a crane hook for a lifting capacity of 50KN with 50 percent overload. Sketch the designed

hook and mention the dimension on it. (20) June 08

Q.27 A four stroke Diesel Engine has the following specification:

Brake power=5KW, Speed=1200rpm, Indicated mean effective pressure=0.35N/mm2, Mechanical

efficiency=80% Determine the Base and length of the cylinder , Thickness of cylinder head, Size of studs

for cylinder head (20) May.09

Q.28 A single cylinder double acting steam engine develops 150KW at mean speed of 80rpm. The

coefficient of fluctuation of energy is 0.1 and fluctuation of speed is ±2% of the mean speed. If the mean

dia. Of flywheel rim is 2m and hub and spokes provide 5% of rotational inertia of the wheel, Find the

MECHANICAL ENGINEERING DEPARTMENT, OITM

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mass of the flywheel and cross sectional area of the rim. Assume the Density of the flywheel material(cast

iron) as 7200 kg/m3. (20) May09

Q.29 Design a connecting rod for a petrol engine from the following data:

Diameter of piston=110mm

Mass of reciprocating parts,M=2Kg

Length of connecting rod,1=325mm

Stroke,L=150mm

Compression ratio=4:1

Speed=1500rpm with possible over speed of 2500rpm

Max. explosion pressure=2.5Mpa (20) June10

Q.30 Design and draw a cast iron flywheel used for a four stroke IC engine developing 180KW at

240rpm.The hoop or centrifugal stress developed in the flywheel 5.2 Mpa, the total fluctuation of speed is

to be limited to 3% of the mean speed. The work done during the power stroke is 1/3 more than the

average work done during the whole cycle. The max. torque on the shaft is twice the main torque. The

density of cast iron is 7220kg/mm3. (20) June.10

Q.31 Design a crane hook with useful load lifting capacity of the crane 40KN. The weight of the hook

with grabbing tongs is 10KN. (20) May11

Q.32 Design a cast iron piston for a single acting four stroke engine for the following specification:

Cylinder bore=100mm

Stroke=120mm

Maximum gas pressure=5N/mm2

Brake mean effective pressure=0.65N/mm2

Fuel consumption =0.227kg/k W/hr

Speed =2200rpm

Assume suitable data, (20) May11