Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Summer 7th Sem New 2171909 Machine Design Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2171909 Date:18/05/2019
Subject Name:Machine Design
Time:02:30 PM TO 05:30 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of design data book is permitted.
MARKS
Q.1 (a) List the major advantages of using geometric progression of for speed
regulation in a gear box.
03
(b) Classify different types of bearings. 04
(c)
Explain different types of gear tooth failures, causes and their possible
remedies.
07
Q.2 (a) List the merits and demerits of worm gear drives. 03
(b) Derive the equation for formative number of teeth for helical gears. 04
(c) Design a pair of straight teeth spur gears to transmit 20 kW when the
pinion rotates at 300 r.p.m. The velocity ratio is 1 : 3. The allowable
static stresses for the pinion and gear materials are 120 MPa and 100
MPa respectively. The pinion has 15 teeth and its face width is 14 times
the module. Assume steady load condition and 8-10 hours of service
per day.
Take, the tooth form factor, y = 0.154 ? ( 0.912 / No. of teeth ); and
the velocity factor, Cv = 3 / ( 3 + v ).
07
OR
(c) Considering static strength determine a suitable module and face width
for a pair of helical gears that 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. The gears are made of cast steel having allowable static
strength of 100 MPa. Assume endurance strength of gear material = 618
MPa.
Also, check the gears for wear.
07
Q.3 (a) Explain the significance of L/D ratio and minimum oil-film thickness
in hydrodynamic bearings.
03
(b) Differentiate between Hydrodynamic and Hydrostatic bearings. 04
(c) Find the range ratio, geometric progression ratio and spindle speeds for
the following data: Nmin = 100 r.p.m., Nmax = 1800 r.p.m. and number
of speed steps = 8.
Also, draw all possible structure diagrams.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2171909 Date:18/05/2019
Subject Name:Machine Design
Time:02:30 PM TO 05:30 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of design data book is permitted.
MARKS
Q.1 (a) List the major advantages of using geometric progression of for speed
regulation in a gear box.
03
(b) Classify different types of bearings. 04
(c)
Explain different types of gear tooth failures, causes and their possible
remedies.
07
Q.2 (a) List the merits and demerits of worm gear drives. 03
(b) Derive the equation for formative number of teeth for helical gears. 04
(c) Design a pair of straight teeth spur gears to transmit 20 kW when the
pinion rotates at 300 r.p.m. The velocity ratio is 1 : 3. The allowable
static stresses for the pinion and gear materials are 120 MPa and 100
MPa respectively. The pinion has 15 teeth and its face width is 14 times
the module. Assume steady load condition and 8-10 hours of service
per day.
Take, the tooth form factor, y = 0.154 ? ( 0.912 / No. of teeth ); and
the velocity factor, Cv = 3 / ( 3 + v ).
07
OR
(c) Considering static strength determine a suitable module and face width
for a pair of helical gears that 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. The gears are made of cast steel having allowable static
strength of 100 MPa. Assume endurance strength of gear material = 618
MPa.
Also, check the gears for wear.
07
Q.3 (a) Explain the significance of L/D ratio and minimum oil-film thickness
in hydrodynamic bearings.
03
(b) Differentiate between Hydrodynamic and Hydrostatic bearings. 04
(c) Find the range ratio, geometric progression ratio and spindle speeds for
the following data: Nmin = 100 r.p.m., Nmax = 1800 r.p.m. and number
of speed steps = 8.
Also, draw all possible structure diagrams.
07
2
OR
Q.3 (a) How the bevel gears are classified ? Explain with neat sketches. 03
(b) Explain interference and undercutting in involute gear tooth profile. 04
(c) A full journal bearing of 50 mm diameter and 100 mm long has a
bearing pressure of 1.4 N/mm
2
. The speed of the journal is 900 r.p.m.
and the ratio of journal diameter to the diametral clearance is 1000. The
bearing is lubricated with oil whose absolute viscosity at the operating
temperature of 75 ?C may be taken as 0.011 kg/m-s. The room
temperature is 35 ?C. Find : 1. The amount of artificial cooling required,
and 2. The mass of the lubricating oil required, if the difference between
the outlet and inlet temperature of the oil is 10?C. Take specific heat of
the oil as 1850 J / kg / ?C.
07
Q.4 (a) Discuss advantages of rolling contact bearings over sliding contact
bearings.
03
(b) Derive the equation for equivalent dynamic load for bearing under
cyclic loads.
04
(c) A four stroke diesel engine has the following specifications :
Brake power = 5 kW; Speed = 1200 r.p.m.; Indicated mean effective
pressure = 0.35 N/mm
2
; Mechanical efficiency = 80 %.
Determine: 1. Bore and length of the cylinder; 2. Thickness of the
cylinder head; and 3. Size of studs for the cylinder head.
Take, Allowable circumferential stress for cylinder material = 42 MPa,
and Allowable tensile strength of material for stud = 65 MPa.
07
OR
Q.4 (a) With neat sketch explain the ?inertia bending forces? acting on
connecting rod of an Internal Combustion (IC) engine.
03
(b) Describe the design procedure of a crank shaft of an Internal
Combustion (IC) engine.
04
(c) Select a single row deep groove ball bearing for a radial load of 4000 N
and an axial load of 5000 N, operating at a speed of 1600 r.p.m. for an
average life of 5 years (300 days/year) at 10 hours per day. Assume
uniform and steady load.
07
Q.5 (a) List the basic objectives of material handling systems. 03
(b) Explain with neat sketches : Construction and designation of steel wire
ropes.
04
(c) A crane hook having an approximate trapezoidal section is shown in
Figure 1. The hook is made of plain carbon steel 45C8 (yield strength
= 380 MPa) and the f.o.s. is 3.5. Determine the load carrying capacity
of the hook.
07
OR
Q.5 (a) Explain different types of loads handled by material handling
equipments.
03
(b) A crane is lifting a load of 25 kN through a wire rope and a hook. The
weight of hook, etc. is 15 kN. The rope drum diameter may be taken as
3 times the diameter of the rope. The load is to be lifted with an
04
FirstRanker.com - FirstRanker's Choice
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2171909 Date:18/05/2019
Subject Name:Machine Design
Time:02:30 PM TO 05:30 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of design data book is permitted.
MARKS
Q.1 (a) List the major advantages of using geometric progression of for speed
regulation in a gear box.
03
(b) Classify different types of bearings. 04
(c)
Explain different types of gear tooth failures, causes and their possible
remedies.
07
Q.2 (a) List the merits and demerits of worm gear drives. 03
(b) Derive the equation for formative number of teeth for helical gears. 04
(c) Design a pair of straight teeth spur gears to transmit 20 kW when the
pinion rotates at 300 r.p.m. The velocity ratio is 1 : 3. The allowable
static stresses for the pinion and gear materials are 120 MPa and 100
MPa respectively. The pinion has 15 teeth and its face width is 14 times
the module. Assume steady load condition and 8-10 hours of service
per day.
Take, the tooth form factor, y = 0.154 ? ( 0.912 / No. of teeth ); and
the velocity factor, Cv = 3 / ( 3 + v ).
07
OR
(c) Considering static strength determine a suitable module and face width
for a pair of helical gears that 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. The gears are made of cast steel having allowable static
strength of 100 MPa. Assume endurance strength of gear material = 618
MPa.
Also, check the gears for wear.
07
Q.3 (a) Explain the significance of L/D ratio and minimum oil-film thickness
in hydrodynamic bearings.
03
(b) Differentiate between Hydrodynamic and Hydrostatic bearings. 04
(c) Find the range ratio, geometric progression ratio and spindle speeds for
the following data: Nmin = 100 r.p.m., Nmax = 1800 r.p.m. and number
of speed steps = 8.
Also, draw all possible structure diagrams.
07
2
OR
Q.3 (a) How the bevel gears are classified ? Explain with neat sketches. 03
(b) Explain interference and undercutting in involute gear tooth profile. 04
(c) A full journal bearing of 50 mm diameter and 100 mm long has a
bearing pressure of 1.4 N/mm
2
. The speed of the journal is 900 r.p.m.
and the ratio of journal diameter to the diametral clearance is 1000. The
bearing is lubricated with oil whose absolute viscosity at the operating
temperature of 75 ?C may be taken as 0.011 kg/m-s. The room
temperature is 35 ?C. Find : 1. The amount of artificial cooling required,
and 2. The mass of the lubricating oil required, if the difference between
the outlet and inlet temperature of the oil is 10?C. Take specific heat of
the oil as 1850 J / kg / ?C.
07
Q.4 (a) Discuss advantages of rolling contact bearings over sliding contact
bearings.
03
(b) Derive the equation for equivalent dynamic load for bearing under
cyclic loads.
04
(c) A four stroke diesel engine has the following specifications :
Brake power = 5 kW; Speed = 1200 r.p.m.; Indicated mean effective
pressure = 0.35 N/mm
2
; Mechanical efficiency = 80 %.
Determine: 1. Bore and length of the cylinder; 2. Thickness of the
cylinder head; and 3. Size of studs for the cylinder head.
Take, Allowable circumferential stress for cylinder material = 42 MPa,
and Allowable tensile strength of material for stud = 65 MPa.
07
OR
Q.4 (a) With neat sketch explain the ?inertia bending forces? acting on
connecting rod of an Internal Combustion (IC) engine.
03
(b) Describe the design procedure of a crank shaft of an Internal
Combustion (IC) engine.
04
(c) Select a single row deep groove ball bearing for a radial load of 4000 N
and an axial load of 5000 N, operating at a speed of 1600 r.p.m. for an
average life of 5 years (300 days/year) at 10 hours per day. Assume
uniform and steady load.
07
Q.5 (a) List the basic objectives of material handling systems. 03
(b) Explain with neat sketches : Construction and designation of steel wire
ropes.
04
(c) A crane hook having an approximate trapezoidal section is shown in
Figure 1. The hook is made of plain carbon steel 45C8 (yield strength
= 380 MPa) and the f.o.s. is 3.5. Determine the load carrying capacity
of the hook.
07
OR
Q.5 (a) Explain different types of loads handled by material handling
equipments.
03
(b) A crane is lifting a load of 25 kN through a wire rope and a hook. The
weight of hook, etc. is 15 kN. The rope drum diameter may be taken as
3 times the diameter of the rope. The load is to be lifted with an
04
3
acceleration of 1 m/s
2
. Calculate the diameter of the wire rope. Take
f.o.s. of 6 and Young?s modulus for the wire rope 80 kN/mm
2
. The
ultimate stress may be taken as 1800 Mpa. The cross-sectional area of
the wire rope may be taken as 0.38 times the square of the wire rope
diameter.
(c) Explain the need of material handling equipments. Also, Classify
material handling equipments.
07
Figure 1
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This post was last modified on 20 February 2020