DESIGN OF TRANSMISSION SYSTEMS QUESTION BANK

R.M.K COLLEGE OF ENGINEERING
AND TECHNOLOGY
RSM NAGAR, PUDUVOYAL-601206
DEPARTMENT OF MECHANICAL ENGINEERING
ME6601 – DESIGN OF TRANSMISSION SYSTEM
VI SEM MECHANICAL ENGINEERING
Regulation 2013
QUESTION BANK
PREPARED BY
R.ASHOK KUMAR M.E, (Ph.D.)
S.ARUNKUMAR M.E, (Ph.D.)

R.M.K COLLEGE OF ENGG AND TECH / AQ / R2013/ ME6601 / VI / MECH / DEC 2017 – MAY 2018
ME6601 – DESIGN OF TRANSMISSION SYSTEM QUESTION BANK by ASHOK KUMAR.R & ARUNKUMAR.S
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ME6601 – DESIGN OF TRANSMISSION SYSTEMS
UNIT – I DESIGN OF FLEXIBLE ELEMENTS 9
Design of Flat belts and pulleys - Selection of V belts and pulleys – Selection of hoisting wire
ropes and pulleys – Design of Transmission chains and Sprockets.
UNIT – II SPUR GEARS AND PARALLEL AXIS HELICAL GEARS 9
Speed ratios and number of teeth-Force analysis -Tooth stresses - Dynamic effects – Fatigue
strength - Factor of safety - Gear materials – Design of straight tooth spur & helical gears based
on strength and wear considerations – Pressure angle in the normal and transverse plane-
Equivalent number of teeth-forces for helical gears.
UNIT – III BEVEL, WORM AND CROSS HELICAL GEARS 9
Straight bevel gear: Tooth terminology, tooth forces and stresses, equivalent number of teeth.
Estimating the dimensions of pair of straight bevel gears. Worm Gear: Merits and demerits-
terminology. Thermal capacity, materials-forces and stresses, efficiency, estimating the size of
the worm gear pair. Cross helical: Terminology-helix angles-Estimating the size of the pair of
cross helical gears.
UNIT – IV GEAR BOXES 9
Geometric progression - Standard step ratio - Ray diagram, kinematics layout -Design of sliding
mesh gear box - Design of multi speed gear box for machine tool applications - Constant mesh
gear box - Speed reducer unit. – Variable speed gear box, Fluid Couplings, Torque Converters
for automotive applications.
UNIT – V CAMS, CLUTCHES AND BRAKES 9
Cam Design: Types-pressure angle and under cutting base circle determination-forces and
surface stresses. Design of plate clutches –axial clutches-cone clutches-internal expanding rim
clutches- Electromagnetic clutches. Band and Block brakes - external shoe brakes – Internal
expanding shoe brake. TOTAL: 45 PERIODS
TEXT BOOKS:
 Bhandari V, “Design of Machine Elements”, 3rd Edition, Tata McGraw-Hill Book Co, 2010.
 Joseph Shigley, Charles Mischke, Richard Budynas and Keith Nisbett “Mechanical
Engineering Design”, 8th Edition, Tata McGraw-Hill, 2008.
REFERENCES:
 Sundararajamoorthy T. V, Shanmugam .N, “Machine Design”, Anuradha Publications,
Chennai, 2003.
 Prabhu. T.J., “Design of Transmission Elements”, Mani Offset, Chennai, 2000.

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COURSE OUTCOMES:
After successful completion of the course, the students should be able to
MAPPING OF COURSE OUTCOMES WITH PROGRAM OUTCOMES:
CO No. Course Outcomes
Highest
Cognitive
Level
C311.1
Design flexible elements like belts, chains and wire ropes for real
applications.
K4
C311.2 Design spur and Helical gear considering strength and wear. K4
C311.3
Design worm, bevel and double helical gear with their associated
parameters.
K4
C311.4 Develop gear box for automotive application. K4
C311.5 Design cam, clutches and brakes for varied application. K4
C311.6
Develop the components related power transmission used in Engine
and machines
K4
Course
Out
Comes
Level
of CO
Program Outcomes
Program Specific
Outcomes
K3 K4 K5 K5
K3,K5
,K6
A3 A2 A3 A3 A3 A3 A2
PSO-
1
PSO-
2
PSO-
3PO-
1
PO-
2
PO-
3
PO-
4
PO-5
PO-
6
PO-
7
PO-
8
PO-
9
PO-
10
PO-
11
PO-
12
C311.1 K4 2 3
C311.2 K4 2 3
C311.3 K4 2 3
C311.4 K4 2 3
C311.5 K4 2 3
C311.6 K4 3 3

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UNIT – I – DESIGN OF FLEXIBLE ELEMENTS
PART - A
1.1) What is a power drive? Mention their types.
1.2) What is meant by mechanical drives?
1.3) State the law of belting.
1.4) Why are belt drives called as flexible drives?
1.5) What are the types of belts?
1.6) Name different types of belts. [AU, Nov / Dec – 2017]
1.7) What is meant by the ply of belt? [AU, Nov / Dec –2013]
1.8) What is meant by ply in a flat belt? [AU, Apr / May – 2016]
1.9) Mention the different types of joints employed for joining flat - belts.
1.10) Mention the materials used for making belts. [AU, Nov / Dec – 2011]
1.11) Name the few materials for belt drives. [AU, Apr / May – 2016]
1.12) What are the materials used for belt – drive? [AU, May / Jun – 2013]
1.13) Why should the tight - side of the belt be at the bottom side of the pulley?
[AU, Apr / May – 2005]
1.14) Differentiate open - belt drive and cross - belt drive.
1.15) Distinguish between open drive and cross drive of a belt drive. Which is better?
[AU, Apr / May – 2011]
1.16) What is belt rating?
1.17) Why are thin wide flat belts preferred over thick narrow belts?
1.18) A longer belt will last more than a shorter belt, why? [AU, Apr / May – 2017]
1.19) Briefly explain initial tension in belts.
1.20) Derive an expression for tension ratio in a belt drive. [AU, May / Jun – 2007]
1.21) Give an expression for ratio of tensions in a flat belt drive.
[AU, Nov / Dec –2012]
1.22) What is the condition to transmit maximum power in a flat belt drive?
[AU, Nov / Dec – 2016]
1.23) Why tight – side of the belt should be at the bottom side of the pulley?
[AU, Nov / Dec –2004, May / Jun – 2006]

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1.24) What will be the effect on the limiting ratio of tensions of a belt if the co-
efficient of friction between the belt and rim of pulley is doubled while angle of lap
remains the same? [AU, Nov / Dec –2007]
1.25) What are the various losses in the power transmission by belts?
[AU, Nov / Dec –2005, 2008]
1.26) Mention the losses in belt drives. [AU, Nov / Dec –2014]
1.27) Why is the face of a pulley crowned? [AU, Nov / Dec –2009]
1.28) Define the term "crowning of pulley". [AU, Nov / Dec – 2016]
1.29) Explain the term crowning of pulley.[AU, Apr / May – 2005, May / Jun – 2011]
1.30) Brief the term "Crowning of Pulley [AU, May / Jun – 2014]
1.31) Specify the purpose of crowning of flat pulley.
1.32) What is crowning of pulley? Specify the purpose of crowning of pulley.
[AU, May / Jun – 2006]
1.33) What is the effect of centre distance and diameter of pulley on the life of a belt?
[AU, Nov / Dec –2005]
1.34) Explain briefly about creep in belts.
1.35) State the reasons for V – belt drive being preferred to flat belt drive?
[AU, Nov / Dec –2010]
1.36) Write a brief note on adjustment of belt tensions.
1.37) State the condition for maximum power transmission in a belt drive.
1.38) Write the different types of pulleys used in belt drives.
1.39) When is a split pulley used? How is it tightened on a shaft?
1.40) When do you use stepped pulley drive? [AU, Apr / May – 2016]
1.41) Write a brief note on fast and loose pulley.
1.42) What are the factors upon which the coefficient of Giction between the belt and
pulley depends? [AU, May / Jun – 2014]
1.43) Sketch the cross - section of a V- belt and label its important parts.
[AU, Nov / Dec –2009]
1.44) How is a V - belt specified? [AU, May / Jun – 2012, Nov / Dec –2012]
1.45) What are the advantages of V belt drive? [AU, Nov / Dec –2012]
1.46) What are the advantages and disadvantages of V - belt drive over flat belt drive?
[AU, May / Jun – 2011]

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1.47) Write the advantages of V - belt over flat belt. [AU, Nov / Dec – 2017]
1.48) Mention the disadvantages of V belts over flat belts. [AU, May / Jun – 2012]
1.49) Define a) pitch length b) inside length
1.50) In what ways are the timing belts superior to ordinary V belts?
[AU, May / Jun – 2006, 2007, Apr / May – 2015]
1.51) Give the relationship of ratio of tensions in a V-belt drive.
[AU, Apr / May – 2008]
1.52) Why slip is less in the case of V – belts when compared with flat belts?
[AU, May / Jun – 2013]
1.53) Define maximum tension in a belt. [AU, Apr / May – 2008]
1.54) What is centrifugal effect on belts? [AU, Nov / Dec –2015]
1.55) Give the condition for maximum power transmission in terms of centrifugal
tension in case of belt drive. [AU, May / Jun – 2009, 2011]
1.56) How the ends of flat are – belt joined? [AU, Apr / May – 2010]
1.57) What are the five parts of roller chain? [AU, Apr / May – 2010]
1.58) Specify the five parts of roller chain. [AU, Nov / Dec –2011]
1.59) What do you mean by galling of roller chains? [AU, Nov / Dec –2010]
1.60) Mention the materials used for making link plates in chain drives.
[AU, May / Jun – 2012]
1.61) What are the features of a chain drive?
1.62) What is chordal action in chain drives? [AU, Nov / Dec –2015]
1.63) What is done to accommodate initial sag in chain drive?[AU, May / Jun – 2007]
1.64) What is meant by chordal action in chain drives? [AU, Apr / May – 2004, 2010]
1.65) What is meant by chordal action of chain? Also name a company theta produces
driving chains. [AU, Apr / May – 2015]
1.66) What factors will affect the working conditions of the chain drive?
[AU, Nov / Dec – 2016]
1.67) List the chain drive failures. [AU, Nov / Dec – 2017]
1.68) In chain drives, the sprocket has odd number of teeth and the chain has even
number of links. Why? [AU, Nov / Dec –2012]
1.69) What are the advantages and disadvantages of chain drives?

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1.70) Give any three applications of chain drives. What are their limitations?
[AU, Apr / May – 2011]
1.71) Give the advantages of chain drives over belt drives. [AU, May / Jun – 2012]
1.72) Under what circumstances chain drives are preferred over V belt drives?
[AU, Apr / May – 2016]
1.73) What are the possible ways by which a chain drive may fail?
1.74) What do you understand by simplex, duplex and triplex chains?
[AU, May / Jun – 2007]
1.75) Distinguish between bush chain and roller chain.
1.76) In what way is a silent chain better than an ordinary driving chain?
[AU, Apr / May – 2005, Nov / Dec –2008, May / Jun – 2011]
1.77) What is a silent chain? In what situations, silent chains are preferred?
[AU, Nov / Dec –2007]
1.78) What is meant by chordal action of chain? Also name a company that produces
driving chains. [AU, May / Jun – 2006]
1.79) What is a slack adjuster? [AU, Nov / Dec –2004]
1.80) What is the reason for using even number of pitches of length in chains?
1.81) Describe fiber ropes.
1.82) Sketch and name the different types of compound wire ropes.
[AU, Apr / May – 2004, 2010]
1.83) How the wire ropes are designated? [AU, Nov / Dec – 2016]
1.84) Under what circumstances is a fiber rope and a wire rope used?
1.85) How are wire - rope ends fastened?
1.86) How is a wire - rope designated? [AU, May / Jun – 2007]
1.87) How is a wire rope specified? [AU, May / Jun – 2009]
1.88) What kind of stresses should be considered during the selection of wire - ropes?
1.89) Give the application of the following wire ropes (a) 6 x 7 rope (b) 6 x
19 rope (c) 6 x 37 rope
1.90) How is a wire rope specified? [AU, May / Jun – 2009]
1.91) What do you understand by 6 x 19 construction in wire ropes?
[AU, Nov / Dec –2014]
1.92) Where are rope - drives employed?

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1.93) Write any four wire rope applications. [AU, Nov / Dec –2013]
1.94) List the advantages of wire ropes compared to chains. [AU, Apr / May – 2017]
1.95) What are the advantages of belt drives in compare with that of the chain and
rope drives? [AU, Nov / Dec – 2017]
PART – B
1.96) Design a belt drive to transmit 30 HP at 740 rpm to an Aluminium rolling
machine; the speed ratio being 3.0; the distance between the pulleys is 3 m;
diameter of the rolling machine pulley is 1.2 m.
1.97) A stone crushing machine receives power from a motor rated at 50 KW at 1800
rpm by means of flat belts. The pulley diameters are 200 mm and 700 mm. The
centre distance between the two pulleys is 4000 mm. Design the belt drives if the
direction of rotation of the two pulleys are opposite to each other.
1.98) Design a fabric belt to transmit 12 KW from an engine running at 1200 rpm to
machine shaft at 480 rpm. The diameter of engine shaft pulley is 300 mm and the
distance of the engine shaft from machine shafts is 2m. m = 0.2 (using fundamental
formulae).
1.99) Design a flat belt drive to transmit 20 KW at 730 rpm to a rolling machine with a
speed ratio of 3. The centre distance is nearly 3.5m. The diameter of rolling
machine pulley is 1.2m.
1.100) Design a flat belt drive to transmit 110 kW for a system consisting of two
pulleys of diameters 0.9m and 1.2m respectively, for a center distance of 3.6m, belt
speed of 20m/s and coefficient of friction = 0.3. There is a slip of 1.2% at each
pulley and 5% friction loss at each shaft with 20% over load.
[AU, Nov / Dec –2008, 2009, 2016, Apr / May – 2016]
1.101) Select a flat belt to drive a mill at 250 rpm from a 10 kW, 730 rpm motor.
Centre distance is to be around 2m. The mill shaft pulley is of 1 m diameter.
[AU, Apr / May – 2011, 2016]
1.102) The head stock spindle of an ordinary lathe is to have three fast speed 225, 300
and 375 rpm by means of a 3 - step cone pulley. Another cone pulley of identical
dimensions is carried on the 3 KW electric motor shaft running at 300 rpm. The
power is transmitted by a flat belt. Assuming the centre distance between motor

9
shaft and spindle as 60 cm and m = 0.25, design the drive, if the minimum diameter
of cone pulley is to be 10 cm.
1.103) It is required to design a leather crossed belt drive to connect 7.5 KW, 1440
rpm electric motor to a compressor running at 480 rpm. The distance between the
centers of the pulley is twice the diameter of the bigger pulley. The belt should
operate at 20 m/s approximately and its thickness is 5 mm. The density of leather is
950 kg/m3
and the permissible stress is 5.6 MPa. Give the design.
[AU, Nov / Dec –2004, Apr / May – 2010]
1.104) A compressor is to run by a motor pulley running at 1440 rpm, speed ratio 2.5.
Choose a flat belt crossed drive. Centre distance between pulleys is 3.6m. Take belt
speed as 16 m/s. Load factor is 1.3. Take a 5 – ply, flat Dunlop belt. Power to be
transmitted is 12kW. High speed load rating is 0.0118 kW/ply/mm width at
V=5m/s. Determine the width and length of the belt. [AU, Nov / Dec –2014]
1.105) A compressor is driven by a 15 kW motor, running at 960 rpm, through an
open belt drive. The speed of the compressor pulley is 480 rpm. The centre
distance of the drive is 2.5m. Select a flat belt drive. Neglect the effect of slip.
[AU, Nov / Dec – 2016]
1.106) A flat belt drive is to design to drive a flour mill. The driving power
requirements of the mill 22.5kW at 750rpm with a speed reduction of 3. The
distance between the shafts is 3m. Diameter of the mill pulley is 1.2m. Design and
make a neat sketch of the drive. [AU, May / Jun – 2012]
1.107) It is required to select a flat-belt drive for a fan running at 360 rpm which is
driven by a 10 KW, 1440 rpm motor. The belt drive is open - type and space is
available for a center distance of 2 m approximately. The belt velocity should be
between 17.8 to 22.9 m/s. The power transmitting capacity of the belt per mm width
per ply at 180ᵒ arc of contact and a belt velocity of 5.08 m/s is 0.0118 KW. The
load correction factor can be taken as 1.2.
1.108) A leather belt 9 mm x 250 mm is used to drive a cast iron pulley 900 mm in
diameter at 336 rpm. If the active arc on the smaller pulley is 120º and stress in
tight side is 2 MPa, find the power capacity of the belt. The density of the leather
may be taken as 980 kg/m3
and co-efficient of friction of leather on cast iron is 0.35.
[AU, May / Jun – 2007, Apr / May – 2010]

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1.109) Design a flat belt drive to transmit 25 kW at 720 rpm to an Aluminium rolling
machine with a speed reduction of 3.0. The distance between the shafts is 3 m.
Diameter of the rolling machine pulley is 1.2 m. [AU, May / Jun – 2009]
1.110) Design a flat belt drive to transmit 6kW at 900 rpm of the driver pulley. Speed
reduction is to be 2.5:1. Assume that the service is service is 16 hours a day.
[AU, Apr / May – 2010]
1.111) Design a flat belt drive for the following data: Power to be transmitted = 22.5
kW; Driver speed = 740 rpm; speed ratio = 3; Distance between the pulleys = 3m;
Larger pulley diameter= 1.2 m. [AU, Nov / Dec –2011]
1.112) Design a V-belt drive to the following specifications
[AU, May / Jun – 2013, Nov / Dec – 2017]
Power to be transmitted = 75 KW
Speed of driving wheel = 1440 rpm
Speed of driven wheel = 400 rpm
Diameter of driving wheel = 300 mm
Centre distance = 2500 mm
Service = 16 hrs / day.
1.113) Design a V-belt drive to the following specifications [AU, Apr / May – 2015]
Power to be transmitted = 7.5 KW
Speed of driving wheel = 1000 rpm
Speed of driven wheel = 300 rpm
Diameter of driven pulley = 500 mm
Diameter of driver pulley = 150 mm
Centre distance = 925 mm.
1.114) A V - belt drive is to transmit 15 KW to a compressor. The motor runs at 1150
rpm and the compressor is to run at 400 rpm. Determine the
(i) Belt specifications
(ii) Number of belts
(iii)Correct centre distance and

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(iv) Drive pulley diameter [AU, Nov / Dec –2005]
1.115) A V belt is to transmit 50kW in a heavy duty saw mill which works in two
shifts of 8 hours each. The speed of the motor is 1440rpm with an approximate
speed reduction of 2 in the machine shaft. The peripheral speed of the belt should
not exceed 24m/sec. Design the drive. [AU, Apr / May – 2004]
1.116) A V – belt drive with 10 belts and a belt speed of 25 m/s transmits 120 kW.
The angle of lap for each belt is 160° and the groove angle is 35°. The coefficient
of friction between the belt and pulley is 0.2. Assuming that the belts are just on the
point of slipping, find the tensions in the tight and slack sides of the belt. The mass
of each belt is 0.6b kg/m. [AU, Nov / Dec – 2017]
1.117) A motor driven blower is to run at 650 rpm driven by electric motor of 7.5 KW
at 1600 rpm. Design the V-belt drive.
1.118) A 50KW, 1160 rpm, AC split phase motor is to be used to drive a reciprocating
pump at a speed of 330 rpm. The pump is for 12hour service and normally requires
44 KW but is subjected to peak loads of 175% of full load. Determine the details of
multiple V - belt drive for this applications.
1.119) Two shafts whose centres are l meter apart are connected by a V - belt drive.
The driving pulley is supplied with 95 KW power and has an effective diameter of
300 mm. It runs at 1000 rpm, while the driven pulley runs at 375 rpm. The angle of
groove on the pulleys is 40ᵒ. Permissible tension in 400 mm2
cross - sectional area
belt is 2.1MPa. The material of the belt has a density of 1100 kg/m3
. The driven
pulley is overhung, the distance of the centre from the nearest bearing being 200
mm. The co - efficient of friction between the belt and the pulley rim is 0.28.
Estimate the number of belts required. [AU, Apr / May – 2005]
1.120) Two shafts whose centers are 1 In. apart are connected by a V- belt drive. The
driving pulley is supplied with 100 kW and has an effective diameter of 300 mm. It
runs at 1000 rpm, while the driven pulley runs at 375 rpm. The angle of groove on
the pulleys is 40°. The permissible tension in 400 mm2
cross sectional area of belt
is 2.1 MPa. The density of the belt is 1100 kg/m3
Taking μ = 0.28, estimate the
number of belts required. Also calculate the length of the each belt.
[AU, Apr / May – 2017]

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1.121) Design a V-belt drive and calculate the actual belt tensions and average stress
for the following data [AU, May / Jun – 2006, 2007, Apr / May – 2010]
Driven pulley diameter (D) = 500 mm
Driver pulley diameter (d) = 150 mm
Center distance (C) = 925 mm
Speeds (N1) = 1000 rpm
(N2) = 300 rpm
Power (P) = 7.5 KW
1.122) A V-belt drive is required for a 1.5 KW, 1440 rpm electric motor which drives
a centrifugal pump running at 360 rpm for a service of 24 hrs per day from the
space considerations. The centre distance should be approximately 1 m. Determine
the
(i) Belt specifications
(ii) Number of belts
(iii)Correct centre distance and
(iv) Drive pulley diameter
1.123) A V-belt drive is required to transmit 16KW power to a compressor. The motor
speed is 1440 rpm and the speed reduction ratio is 3.6. Design the belt drive.
Sketch the details of pulley [AU, May / Jun – 2007]
1.124) Design a V-belt drive to transmit 50 kW at 1440 rpm from an electric motor to
a textile machine running 24 hours a day. The speed of the machine shaft is 480
rpm. [AU, Apr / May – 2008]
1.125) A V – belt drive consist of three V – belts in parallel on grooved pulleys of the
same size. The angle of groove is 30º and the coefficient of friction 0.12. The cross
sectional area of each belt is 800mm2
and the permissible safe stress in the belt
material is 3MPa. Calculate the power that can be transmitted between two pulleys
400mm in diameter rotating at 960rpm. [AU, Nov / Dec –2010]
1.126) Select a suitable V – belt and design the drive for a wet grinder. Power is
available from a 0.5kW motor running at 750rpm. Drum speed is to be about
100rpm. Drive is to be compact. [AU, May / Jun – 2011, 2012, Nov / Dec –2015]

13
1.127) A motor of power 2kW running at a speed of 1400rpm transmits power to an
air blower running at 560rpm. The motor pulley diameter is 200mm. The center
distance may be 1000mm. Design a suitable V – belt drive. [AU, Nov / Dec –2012]
1.128) A crusher running at a speed of 400 rpm is driven by an electric motor of
10kW with a reduction in speed of 3 times. Taking a center distance of 600mm,
design a V – belt drive. [AU, Nov / Dec –2012]
1.129) A centrifugal pump running at 340 rpm is to be driven by a 100 kW motor
running at 1440 rpm. The drive is to work for at least 20 hours every day. The
centre distance between the motor shaft and the pump shaft is 2000 mm, suggest a
suitable multiple V – belt drive for this application. Also calculate the actual belt
tensions and stress induced. [AU, Nov / Dec –2013]
1.130) A V – belt drive is to transmit 45 kW in a heavy duty saw mill which works in
two shifts of 8 hours each. The speed of motor shaft is 1400 rpm with the
approximate speed reduction of 3 in the machine shaft. Design the drive and
calculate the average stress induced in the belt. [AU, May / Jun – 2014]
1.131) It is required to design a chain drive with a duplex chain to connect 15 KW,
1440 rpm electric motor to a transmission shaft at 350 rpm. The operation involves
moderate shocks.
(a) Specify the number of teeth on the driving and driven sprockets.
(b) Select a proper roller chain
(c) Calculate the pitch circle diameters of the driving and driven sprockets.
(d) Determine the number of chain links
(e) Specify the correct centre distance.
1.132) Design a chain drive to actuate a compressor from a 10 KW electric motor at
960 rpm. The compressor speed is to be 350 rpm. The minimum centre distance
should be 0.5 m. Motor is mounted on an auxiliary bed. Compressor is to work for
8hrs/day. [AU, May / Jun – 2012, 2013]
1.133) A 7.5 KW electric motor running at 1400 rpm is used to drive the input shaft of
the gear box of a special purpose machine. Design a suitable roller chain to connect
the motor shaft to the gear box shaft to give an exact speed ratio of 10 to 1. Assume

14
the minimum centre distance between the driver and driven shaft as 600 mm.
[AU, May / Jun – 2006, Apr / May – 2015, 2016]
1.134) Design a suitable chain drive to actuate a compressor from a 10 KW electric
motor. Speed of the motor shaft is 1050 rpm. The compressor speed is to be 350
rpm. The minimum centre distance should be 600mm. Compressor is to work for
12hrs/day [AU, Nov / Dec –2012]
1.135) A roller chain drive is used between a driver shaft running at 1000 rpm and a
driven shaft running approximately at 320rpm. The power transmitted is 10kW.
The drive is to be used for 2 shifts / per day with 8 hours per shift. The center
distance is approximately 700mm and the chain tension can be adjusted by moving
the motor in the rails. Design the drive [AU, Apr / May – 2004]
1.136) A roller chain drive transmits 4 kW power. The driving shaft on an electric
motor runs at 600 rpm and velocity ratio is 5. The drive is required to operate
continuously with periodic lubrication, and drive a machine such that the load can
be regarded as fairly constant. Assuming factor of safety as 14, select the drive and
check for power capacity of it, based on breaking load and bearing pressure.
Assume service factor 2.25. [AU, Nov / Dec – 2017]
1.137) Design a chain drive to actuate a compressor from a 12 KW electric motor at
900 rpm, the compressor being 250 rpm. The minimum centre distance should be
500 mm. The chain tension may be adjusted by shifting the motor on rails. The
compressor is to work 8 hours / day. [AU, Nov / Dec –2005, 2008]
1.138) Design a chain to transmit 7.5KW at 960 rpm of the sprocket pinion. A speed
reduction of 2.5 to 1 is desired. The drive is horizontal and the motor is mounted on
an adjustable base. A service of 12 hrs/ day is engaged.
1.139) A bucket elevator is to be driven by a gear motor and a roller chain drive with
the information given below. Motor output = 7.5 KW; speed = 1400 rpm;
transmission ratio = 10: 1. Assuming a minimum center distance of 550mm
between sprockets, select suitable chain. [AU, Nov / Dec –2012]
1.140) A bucket elevator is to be driven by a geared motor and a roller chain drive
with the information given below: Motor output- 3 kW; Speed of motor shaft - 100
rpm; Elevator drive shaft speed- 42 rpm; Load-even; Distance between centres of
sprockets approximately - 1.2 m; Period of operation- 16 hours/day. Geared motor

15
is mounted on an auxiliary bed for centre distance adjustments. Design the Chain
drive. [AU, Nov / Dec – 2016]
1.141) A blower is to run at 600 rpm. Power to the blower is available from a motor
rated 8 kW at 1500 rpm. Design a chain drive for the system if the centre distance
is to be 800 mm. [AU, Apr / May – 2008]
1.142) A compressor is to be actuated from a 10kW electric motor. The speed of the
motor shaft is 1000rpm and the compressor speed being 350rpm. The minimum
centre distance is 500mm. The compressor operates 16 hours per day. Design a
suitable chain drive. [AU, Nov / Dec –2009]
1.143) Design a chain drive to transmit 6kW at 900rpm of a sprocket pinion. Speed
reduction is 2.5:1. Driving motor is mounted on an adjustable base. Assume that
load is steady, drive is horizontal and service is 16 hours/day.
[AU, Apr / May – 2010]
1.144) The reduction of speed from 360 rpm to 120 rpm is desired by the use of chain
drive. The driving sprocket has 10 teeth. Find the number of teeth on the driven
sprocket. If the pitch radius of the driven sprocket is 250mm and the centre to
centre distance between the two sprockets is 400mm. Find the pitch and length of
the chain. [AU, Nov / Dec –2010]
1.145) Design a chain drive (roller chain) for power to transmitted = 30 KW at a small
sprocket speed of 1000 rpm. The driven shaft runs at 500rpm. The chain will be
subjected to intermittent overloads of 100% (Take KS= 2.0).
1.146) Design a chain drive to run a compressor from a 11 KW electric motor running
at 970 rpm, the compressor speed being 330 rpm. The compressor operates 16
hours/day. The centre distances should be approximately 500 mm. The chain
tension can be adjusted by shifting the motor on slides.
[AU, Nov / Dec –2004, Apr / May – 2010, 2016]
1.147) Design a chain drive to actuate a compressor from 15 KW electric motor
running at 1,000 rpm, the compressor speed being 350 rpm. The minimum centre
distance in 500mm. The compressor operator 15 hours per day the chain tension
may be adjusted by shifting the motor. [AU, May / Jun – 2007, 2014]

16
1.148) A 15 KW squirrel cage motor, 1250 rpm is driving a centrifugal pump at 550
rpm. The centrifugal pump is located at 700 mm from the motor. Design a chain
drive. [AU, Nov / Dec –2007]
1.149) Design a chain drive to activate a compressor from a 15 kW electric motor at
960 rpm. The compressor speed is 300 rpm. The chain tension may be adjusted by
shifting the motor on rails. The compressor is to work 8 hours/day.
[AU, May / Jun – 2009]
1.150) Design a chain drive to a drive a centrifugal compressor from an electric motor
15kW at 1000rpm. The speed reduction ratio required is 2.5. The compressor to
work for 16 hours per day. State solutions for common problems encountered in
continuous operation of the drive. [AU, May / Jun – 2012]
1.151) The transporter of a heat treatment furnace is driven by a 4.5 kW, 1440 rpm
induction motor through a chain drive with a speed reduction ratio of 2.4. The
transmission is horizontal with bath type of lubrication; Rating is continuous with 3
shifts per day. Design the complete chain drive. [AU, Nov / Dec –2013]
1.152) A truck equipped with a 9.5 kW engine uses a roller chain as the final drive to
the rear axle. The driving sprocket runs at 900 rpm and the driven sprocket at 400
rpm with a centre distance of approximately 600 mm. Select the roller chain.
[AU, Apr / May – 2011]
1.153) A truck equipped with a 9.5 kW engine uses a roller chain as the final drive to
the rear axle. The driving sprocket runs at 900 rpm and the driven· sprocket at 400
rpm with a centre distance of approximately 600 mm. Select the roller chain.
Number of teeth on driving sprocket can be taken as 27 and the pitch value can be
taken at the middle of Pmax and Pmin values. [AU, Apr / May – 2017]
1.154) Select a suitable wire - rope from 6 x 37 group to lift a maximum load of 10KN
through a height of 60m. The weight of bucket is 2KN. Maximum lifting speed is 2
m/s which is attained in 3 sec. Drum diameter is 30 times the rope diameter. Factor
of safety is 6.
1.155) Select a suitable wire - rope for EOT from 6 x 37 group to the following data :
Load to be carried = 15 tonnes
Lifting height = 10 m.
Weight of lifting magnet = 3 tonnes

17
Lifting speed = 30 m/minutes.
1.156) Select a suitable wire - rope to lift 20KN of debris from a well of 60m deep.
The weight of the bucket is 4KN. The weight is being lifted with a maximum speed
of 100 m/min and the maximum speed is attained in 2 seconds. Determine also the
stress induced in the rope due to starting with an initial slack of 0.2m.
1.157) Select a wire rope for a vertical mine hoist to lift 1800 tonnes of ore in each 8
hour shift from a depth of 750m. Assume a two compartment shaft with the
hoisting skips in balance. Use a maximum velocity of 720 m/min with acceleration
and deceleration of 15 sec each and a rest period of 10 sec. for discharging and
loading the skips. Hoisting skip weight approximately 0.6 times of its load
capacity. Factor of safety = 6.
1.158) Select a wire rope for a vertical mine hoist to lift 10000kN of coal from a depth
of 750m in each 8 hours shift. Assume a two compartment shaft with hoisting skips
in balance. Assume rope velocity 750m/min, acceleration and deceleration periods
of each 10sec and rest periods of each 10sec for discharging and loading.
Assuming skip weight to be half of that of the load. Take E = 8 * 104
N/mm2
[AU, Apr / May – 2004]
1.159) A workshop crane is lifting a load of 25 KN through a wire rope and a hook.
The weight of the hook is 15 KN. The rope drum diameter may be taken as 30
times the diameter of the rope. The load is to be lifted with an acceleration of 1
m/s2
. Calculate the diameter of the wire rope. Take a factor of safety of 6 and the
Young's modulus for the wire rope is 80 KN / mm2
. 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. [AU, Apr / May – 2005]
1.160) A crane is used to loft a load of 32 KN through a wire rope. Weight of crane of
took is 6 KW. The load is to be lofted with on acceleration of 1.2 m/s2
. Neglecting
self-weight of the rope, design the drive. [AU, May / Jun – 2007]
1.161) A crane is lifting a load of 18 KN through a wire rope and a hook. The weight
of the hook is 10 KN. The load to be lifted with an acceleration of 1 m/s2
.
Calculate the diameter of the wire rope. The rope diameter may be taken as 30
times the diameter of the wire. Take a factor of safety of 6 and young’s modulus of
the wire rope 0.8 x 105N/mm2
. The ultimate stress may be taken as 1800 N/mm2
.

18
The cross- sectional area of the wire rope may be taken as 0.38 times the square of
the rope diameter. [AU, Nov / Dec –2007]
1.162) A workshop crane carries a load of 30 kN using wire ropes and a hook. The
hook weighs 15 kN. Diameter of the rope drum is 30 times the diameter of the
rope. The load is lifted with an acceleration of 1 m/s2
. Find the diameter of the
rope. FS = 6, Er = 80 kN/cm2
,σu = 180 kN/mm2
, cross section of the rope = 0.4 ×
(dia. of rope)2
. [AU, Nov / Dec –2011]
1.163) At the construction site, 1 tonne of steel is to be lifted up to a height of 20 m
with the help of 2 wire ropes of 6 x 19 size, nominal diameter 12 mm, and breaking
load 78 kN. Determine the factor of safety if the sheave diameter is 56 d and if wire
rope is suddenly stopped in 1 second when travelling at a speed of 1.2 m/s. What is
the factor of safety if bending load is neglected? [AU, Nov / Dec –2014]
1.164) Select a wire rope for a vertical mine hoist to lift a load of 20kN from a depth
of 60m. A rope speed is 4 m/s is attained in 10seconds. [AU, Nov / Dec –2015]
1.165) Select a wire rope for a vertical mine hoist to lift a load of 20kN from a depth
of 500m. A rope speed is 3 m/s is attained in 10seconds. [AU, Nov / Dec –2017]
1.166) Design a wire rope for a vertical mine hoist to lift a load 50 kN, from a depth
of 250m. Rope speed of 8 m/s is to be attained in 10 seconds. Take factor of safety
as 6. [AU, Nov / Dec – 2016]

19
UNIT – II – SPUR GEARS AND PARALLEL AXIS HELICAL GEARS
Part – A
2.1) What is a gear drive? Where is it operated?
2.2) Enumerate the advantages and disadvantages of gear - drives over flexible drives.
2.3) Mention some applications of gear drives.
2.4) How are gears classified?
2.5) Label a) addendum b) flank in a simple sketch of a gear tooth.
[AU, May / Jun – 2007]
2.6) Specify the types of gear - failures.
2.7) Which of the material property influences the surface compressive strength of the
gear teeth? [AU, Nov / Dec – 2017]
2.8) What is meant by spur - gear?
2.9) Mention the advantages and disadvantages of non – metallic gears?
[AU, Nov / Dec –2012]
2.10) Mention the disadvantages of non-metallic gears. [AU, Nov / Dec –2011]
2.11) Specify the significance of minimum number of teeth in pinions.
[AU, May / Jun – 2012]
2.12) What condition must be satisfied in order that a pair of spur gears may have a
constant velocity ratio? [AU, Nov / Dec –2009, May / Jun – 2014]
2.13) Define the following terms.(a) tip circle (b) root circle (c) pitch
circle (d)base circle
2.14) What is meant by pressure angle? [AU, May / Jun – 2006]
2.15) What is pressure angle? What is the effect of increase in pressure angle?
[AU, May / Jun – 2006, 2014, Apr / May – 2015]
2.16) What is the effect of increase in pressure angle? [AU, Apr / May – 2005]
2.17) What is the effect of increasing the pressure angle in gears?
[AU, Nov / Dec –2011]
2.18) Specify the effects of increasing the pressure angle in gear design.
[AU, Nov / Dec –2014]
2.19) What are the effects of increasing or decreasing the pressure angle in gear
design? [AU, Apr / May – 2017]

20
2.20) Why is tangential component of gear tooth force called useful component?
[AU, Apr / May – 2010]
2.21) What does the load correction factor account for in gear design?
[AU, May / Jun – 2012]
2.22) Define module. [AU, Apr / May – 2011, May / Jun – 2013, Nov / Dec –2015]
2.23) Specify the following terms (a) circular pitch (b) diametral pitch
2.24) Differentiate between circular pitch and diametral pitch. [AU, Nov / Dec –2013]
2.25) Define the following terms (a) backlash (b) gear ratio
[AU, Apr / May – 2008]
2.26) Define Backlash. What factors influence backlash? [AU, Nov / Dec – 2016]
2.27) Backlash of Spur gear depends on which of two factors?
[AU, Nov / Dec – 2016]
2.28) What is meant by addendum and dedendum?
2.29) Why is dedendum value more than addendum value? [AU, Nov / Dec –2004]
2.30) What is working depth of a gear - tooth?
[AU, Apr / May – 2005, May / Jun – 2011]
2.31) What are the profiles of a spur gear? [AU, Apr / May – 2016]
2.32) What are the common profiles used for gear tooth? [AU, Nov / Dec – 2016]
2.33) Sketch the profile of spur gear and mark terminology used to specify the gear.
[AU, Apr / May – 2010]
2.34) What preliminary design considerations should be adopted while selecting a
gear drive?
2.35) What is beam strength of spur gear? What is the effect of module on bema
strength of a tooth in a spur gear? [AU, Apr / May – 2010]
2.36) State any two important applications where the spur gear is used.
[AU, Nov / Dec – 2017]
2.37) Why is a gear tooth subjected to dynamic loading?
[AU, Nov / Dec –2007, 2014, May / Jun – 2011]
2.38) How does the number of teeth affect the design of gears [AU, Nov / Dec –2005]
2.39) State the law of gearing.
[AU, May / Jun – 2005, 2006, 2007, Nov / Dec –2012, Apr / May – 2015]
2.40) What is interference in gears? How can you overcome it?

21
2.41) Specify the conditions based on which gear cutters are selected.
[AU, Nov / Dec –2004]
2.42) How do spur - gears fail?
2.43) How does failure by pitting happen in gears? [AU, Nov / Dec –2011]
2.44) What stresses are induced in gear tooth?
2.45) What is meant by a corrected gear?
2.46) Briefly explain about contact ratio of gears.
2.47) Write short notes on backlash of gears.
2.48) What are the effects of little backlash and excessive backlash on gears?
2.49) What factors influence that backlash in gear drives?
[AU, Apr / May – 2005, Nov / Dec –2008, May / Jun – 2011]
2.50) What is a form factor?
2.51) What are the effects of little backlash and excessive backlash on gears?
2.52) What factors influence backlash in gear drives? [AU, Apr / May – 2005]
2.53) Specify the types of gear tooth.
2.54) What are the common forms of gear tooth profile? [AU, Apr / May – 2011]
2.55) What are the generally used gear profiles? [AU, May / Jun – 2012]
2.56) What are the commonly used gear tooth profiles? [AU, May / Jun – 2007]
2.57) What are the main types of gear tooth failure? [AU, May / Jun – 2013, 2016]
2.58) Explain full - depth gear - tooth system.
2.59) What is stub tooth? Why it is preferred? [AU, May / Jun – 2012]
2.60) Write short notes on stub - tooth system.
2.61) What is meant by stub tooth in gear drives? [AU, Nov / Dec – 2017]
2.62) Define involute and cycloidal curves.
2.63) Distinguish between internal gearing and external gearing.
2.64) Find the outer diameter of a gear blank for module 2mm and number of teeth 40.
2.65) In a pair of spur gears, the module is 6mm. Determine the circular pitch and
diametral pitch. [AU, Nov / Dec –2010]
2.66) Find the equivalent Young 's modulus for the following data: Young's modulus
for pinion material = 2.0 * 105 N/mm2
& Young's modulus for wheel material = 1.0
* 10 5 N/mm2

22
2.67) Where do we use spiral gears? [AU, Nov / Dec –2013]
2.68) What is helical gear?
2.69) Compare the contact between mating teeth of spur and helical gears.
[AU, Apr / May – 2010]
2.70) In what ways are helical gears different from spur gears?
2.71) Differentiate double helical and herringbone gears.
[AU, Nov / Dec –2015, Apr / May – 2017]
2.72) What are the advantages of helical gears?
2.73) Where do we use helical gears? [AU, Apr / May – 2016]
2.74) State the advantage of helical gear over spur gear.
2.75) Mention a few gear materials. [AU, May / Jun – 2009, 2011]
2.76) What are the advantages of the helical gear over spur gear?
[AU, Nov / Dec –2005, Apr / May – 2008]
2.77) State an advantage and a disadvantage of helical gear.
[AU, May / Jun – 2009, Nov / Dec –2012]
2.78) What is helix angle?
2.79) Differentiate the following terms with respect to helical gears:(a) transverse
circular pitch, (b) normal circular pitch and (c) axial pitch [AU, Nov / Dec –2007]
2.80) A helical gear has a normal pressure angle of 20°, a helix angle of 45°, normal
module of 4 mm and has 20 teeth. Find the Pitch Diameter.
[AU, Nov / Dec – 2016]
2.81) Give a brief account of skew gears.
2.82) Where do we use skew gears? [AU, Nov / Dec –2004, 2008, Apr / May – 2005]
2.83) What are the applications of skew helical gears? [AU, May / Jun – 2011]
2.84) Define virtual number of teeth in helical gears. [AU, Nov / Dec – 2017]
2.85) What is meant by virtual number of teeth?
2.86) What is virtual number of teeth in helical gears? [AU, Nov / Dec –2012]
2.87) Differentiate axial pitch and normal pitch of the helical gear.
2.88) Write the expressions for static strength limiting wear load and dynamic load for
helical gears.
2.89) What is the interference in involute profile? [AU, Nov / Dec –2005, 2008]

23
2.90) State the advantages of herring bone gear.
[AU, May / Jun – 2006, 2007, Apr / May – 2015]
2.91) What is herring bone gear? [AU, Apr / May – 2016]
2.92) What is herring bone gear? Where are they used? [AU, Nov / Dec –2009]
2.93) What is herringbone gear? State its application. [AU, Nov / Dec –2005]
2.94) State the application of herring bone gear. [AU, Apr / May – 2008]
PART – B
2.95) Discuss in detail the procedure for designing of spur gear drive.
2.96) Describe the modes of failure of gears with suitable illustrations.
[AU, Nov / Dec –2012]
2.97) What are all the preliminary considerations that should be taken before
designing a spur gear drive?
2.98) Explain the phenomenon of interference in involute gears.
[AU, May / Jun – 2014]
2.99) Design a pair of spur gear to transmit 20 KW at a pinion speed of 1400 rpm. The
transmission ratio is 4. Assume suitable materials and stresses
2.100) Design a pair of spur gear drive to transmit 7.5 KW at 750 rpm with a speed
reduction of 3. The number of teeth on pinion is to be 20. Assume suitable
material. Check for plastic deformation.
2.101) Design a spur gear pair to transmit 1.5 KW at 1440 rpm from an electric motor
to an air compressor running at 720 rpm. Take the working life as 10,000 hrs. The
material to be used is cast iron grade 25 for both pinion and wheel.
[AU, Nov / Dec –2004]
2.102) An electric motor is to be connected to a reciprocating pump through a gear
pair. The gears are overhanging in their shafts. Motor speed = 1440 rpm. Speed
reduction ratio = 5. Motor power = 36.8 KW. The gears are to have 20º pressure
angle. Design a spur gear drive. [AU, Apr / May – 2005, 2010, Nov / Dec –2008]
2.103) A motor shaft rotating at 1440 rpm has to transmit 15 KW power to a low speed
shaft rotating at 500 rpm. A 20ᵒ pressure angle involute tooth gear pinion is used.
The pinion has 25 teeth. Design a suitable gear drive.[AU, Nov / Dec –2005, 2008]
2.104) A bronze spur pinion rotating at 600 rpm drives a cast iron spur gear at a
transmission ration 4:1. The allowable static stresses for the bronze pinion and cast

24
iron gear are 84MPa and 105MPa respectively. The pinion has 16 standards 20º full
depth involute teeth of module 8mm. The face width of the both gears is 90mm.
Find the power that can be transmitted from the stand point of strength.
[AU, Nov / Dec –2008]
2.105) A motor shaft rotating at 1440 rpm has to transmit 15 KW power to a low speed
shaft rotating at 500 rpm. A teeth are 20ᵒ involute with 25 teeth on the pinion.
Bothe the pinion and gear are made of cast iron with a maximum safe stress of
56MPa. A safe stress of 35MPa may be taken for the shaft on which the gear is
mounted. Design and sketch the spur gear drive to suit the above conditions. The
starting torque may be assumed as 1.25 times the running torque.
[AU, Nov / Dec –2009]
2.106) A 27.5kW power is transmitted at 450 rpm to a shaft running at approximately
112 rpm through a spur gear drive. The load is steady and continuous. Design a
gear drive and check the design. Assume the following materials: Pinion – Heat
treated cast steel; Gear – High grade cast iron. [AU, Nov / Dec –2010]
2.107) A speed reducing unit using spur gears are to be designed. Power to be
transmitted is 60hp and is continuous with moderate shaft loads. The speed of the
shafts is 920 rpm and 144 rpm respectively. The centre distance is kept as small as
possible. Select a suitable material and design the gears. [AU, Apr / May – 2016]
2.108) Design a spur gear drive to transmit 22KW at 900 rpm, speed reduction is 2.5.
Materials for pinion and wheel are C15 steel and cast iron grade 30 respectively.
Take pressure angle of 20º and working life of gears as 10,000 hours.
[AU, May / Jun – 2012]
2.109) Design a pair of straight spur gear drive for a stone crusher, the pinion and
wheel are made of C15 steel and cast iron grade 30 respectively. The pinion is1to
transmit 22 kW power at 900 rpm. The gear ratio is 2.5. Take pressure angle of 20°
and working life of gears as 10,000 hours. [AU, Nov / Dec – 2016]
2.110) Design a spur gear drive to transmit 22.5 kW at 900 rpm. Speed reduction is
2.5. Materials for pinion and wheel are C15 steel and cast iron grade 30
respectively. Take pressure angle of 20º and working life of the gears 10,000 hours.
[AU, Nov / Dec –2013]

25
2.111) Design a spur gear drive for a heavy machine tool with moderate shocks. The
pinion is transmitting 18kW at 1200rpm with a gear ratio of 3.5. Design the drive
and check for elastic stresses and plastic deformation. Make a sketch and label
important dimensions arrived. [AU, May / Jun – 2012]
2.112) Design a spur gear drive to transmit 8kW at 720rpm and the speed ratio is 2.
The pinion and wheel are made of the same surface hardened carbon steel with 55
RC and core hardness less than 350 BHN. Ultimate strength is 720 N/mm2
and
yield strength is 360N/mm2
. [AU, Apr / May – 2015]
2.113) Design a pair of spur gear to transmit 10 KW at 1500 rpm with a gear ratio of
3. Assume same material for both wheels. Check for plastic deformation assuming
instantaneous torque of 50 % higher than the mean torque.
2.114) Design a pair of spur gears to transmit 30kW at a pinion speed of 1400rpm.
The transmission ratio is 4. Assume suitable material. [AU, May / Jun – 2011]
2.115) Design a pair of spur gears to transmit 20 kW at a pinion speed of 1400 rpm.
The transmission ratio is 4. Pinion and gear are made of 15 Ni2 Cr l Mo15 and C45
steels respectively. Assume pressure angle 20° and minimum number of teeth 20.
[AU, Nov / Dec – 2017]
2.116) Design and draw spur gear drive transmitting 30 kW at 400 rpm to another
shaft running approximately at 1000 rpm. The load is steady and continuous. The
material for the pinion is cast steel and for gear is cast iron. Take module as 10
mm. Also check the design for dynamic load and wear. [AU, May / Jun – 2014]
2.117) The following particulars refer to a spur gear drive: Centre distance = 200 mm;
Velocity ratio = 4; Power = 50 kW; Pinion speed = 1440 rpm; Tooth profile 20°,
full depth involute; Permissible normal load between the teeth = 160 N/mm of the
face width min. no. of teeth on pinion is 18. Design the drive. Also, determine the
load on the bearings, stating its nature. Assume that both gears are mounted on
overhanging shafts. [AU, Nov / Dec – 2017]
2.118) A pair of 20ᵒ full depth spur gear is required to transmit 22.5KW. The speed of
the pinion is 3000 rpm and the gear ratio of the drive is 10. The pinion is made of
steel with Brinell hardness number of 250 and gear is made up of ordinary cast
iron. The number of teeth of pinion should be between 15 and 24. The diameter of
the pinion should be approximately 75mm. Design the spur gear drive.

26
2.119) Design a pair of spur gear to drive a lobe - blower from a 120 KW, motor
running at 2880 rpm, with a reduction ratio of 1.6. The pitch diameter of the pinion
is not to be more than 80mm. Drive is an enclosed one with proper lubrication. Life
is being indefinite. Light shock loads are likely.
2.120) A spur gear drive is used to drive a cam - shaft by the crank shaft with a speed
reduction of 2 in a 5KW engine. The centre distance is not to be more than 160mm.
Design the drive for 12,000 hrs. Crank shaft speed is 1300 rpm.
2.121) In a non - reversible type rolling mill drive, a gear is designed to run 24
hrs/day, transmitting power in the following manner (i) 1104 KW normally (ii)
4516 KW for 3 seconds, 600 times a day (iii) 5888 KW maximum (monetary peak
load) at all constant speed of 40 rpm. The life of gears to be 10 years. Determine N
equivalent.
2.122) A pair of straight teeth spur gears is to transmit 30 HP when the pinion rotates
at 300 rpm. The velocity ratio is 1: 3. The allowable static stresses for the pinion
and gear materials are 1200 and 1000 kg/cm2
respectively. The pinion has 15 teeth
and its face width is 14 times the module. Determine (i) module (ii) face width
(iii)pitch circle diameter of both the pinion and the gear from the stand point of
strength only, taking into consideration the effect of dynamic loading.
2.123) Design a spur gear drive to connect an electric motor to a reciprocating pump
both being mounted on the same bed. Speed of the motor is 1440 rpm. Speed
reduction desired is 10:1. Motor power is 36.8 KW. The gears are to have
20ºpressure angle. The minimum number of teeth on pinion is 24 (Using Lewis and
Buckingham equation).
2.124) Design a gear drive to transmit 22KW at 1000 rpm. Speed reduction is 2.5. The
centre distance between the shafts is 350mm. The materials for the pinion and the
wheel are cast steel and cast iron respectively. Pressure angle, φ = 20ᵒ. The design
stress for the pinion material is 84 N/mm2
and the surface endurance limit for the
gear pair is 600 N/mm2
, modulus of elasticity of the pinion material is 2 *105
N/mm2
and that of gear is 1 *105
N/mm2
. (Using Lewis and Buckingham equation).
[AU, Apr / May – 2004]
2.125) The pitch circles of a train of spur gears are shown in Figure. Gear A
receives3.5 kW power at 700 r.p.m through its shaft and rotates in the clockwise

27
direction. Gear B is the idler gear while gear C is the driven gear. The number of
teeth on gears A, B and Care 30, 60 and 40 respectively, while the module is 5 mm.
Calculate: (i) the torque on each gear shaft, and (ii) the components of gear tooth
forces. Draw a free-body diagram of forces and determine the reaction on the idler
gear shaft. Assume the 20 ° involute system for the gears.
[AU, Nov / Dec –2007, Apr / May – 2010]
2.126) Pinion 2 in the following figure runs at 30 rev/s and transmits 2.5 KW to idle
gear 3The teeth are cut on the 20º full - depth system and have a module of m = 2.5
mm. Draw a free - body diagram of gear 3 and show all the forces which act upon
it.
2.127) Referring to the figure given below, spur gear A receives 3 KW at 600 rev /
min through its shaft and rotates clockwise. Gear B is an idler and gear C is the
driven gear. The teeth are 20º full depth. (Pitch circles are shown in the figure)
determine (i)torque each shaft must transmit(ii)tooth load for which each gear must
be designed(iii)force applied to the idler shaft as a result of the gear tooth loads.
[AU, Nov / Dec –2004, 2007]

28
2.128) Two shafts 300 mm apart transmitting 7.46 KW are to be connected by a steel
pinion meshing with a cast iron gear. The velocity ratio of the drive is 3:1 and the
pinion runs at 600 rpm. Assume 20º involute tooth profile, design the drive
[AU, May / Jun – 2006]
2.129) Design a straight spur gear drive to transmit 8 KW. The pinion speed is 720
rpm and the speed ratio is 2. Both the gears are made of the same surface hardened
carbon steel with 55RC and core hardness less than 350 BHN. Ultimate strength is
720 N/mm2
and yield strength is 360 N/mm2
[AU, May / Jun – 2006, 2007]
2.130) Design a pair of straight spur gears to transmit 12kW at 1500rpm. Speed
reduction required is 4. Check for compressive and bending stresses. Also check
for plastic deformation of teeth. Make a schematic diagram and show the results
neatly. [AU, Nov / Dec –2012]
2.131) Design a straight spur gear drive. Transmitted power 8kW. Pinion speed
764rpm. Speed ratio is 2. The gears are to be made of C45 steel. Life is to be
10,000hours. [AU, May / Jun – 2013]
2.132) A motor shaft rotating at 1500 rpm has to transmit 15 kW to a low speed shaft
with a speed reduction of 3:1. Assume starting torque to be 25% higher than the
running torque. The teeth are 20ºinvolute with 25 teeth on the pinion. Both the
pinion and gear are made of C45 steel. Design a spur gear drive to suit the above
conditions and check for compressive and bending stresses and plastic deformation.
Also sketch the spur gear drive. [AU, Apr / May – 2008]
with a speed reduction of 3:1. The teeth are 20º involute with 25 teeth on the
pinion. Both the pinion and gear are the made of steel with a maximum safe stress
of 200 N/mm2
. A safe stress of 40N/mm2
may be taken for the shaft on which the

29
gear is mounted and also for the key. Design a spur gear drive to suit the above
conditions. Assume starting torque to be 25% higher than the running torque.
[AU, Nov / Dec –2011]
with a speed reduction of 4:1. The teeth are 20º involute with 20 teeth on the
pinion. Both the pinion and gear are the made of steel with a maximum safe stress
of 230 N/mm2
. A safe stress of 50N/mm2
may be taken for the shaft on which the
gear is mounted and also for the key. Design a spur gear drive to suit the above
conditions. Assume starting torque to be 30% higher than the running torque.
[AU, Nov / Dec –2012]
2.135) A motor shaft running at 1440 rpm has to transmit 15 KW power to a low
speed shaft rotating at 480 rpm. The pinion has 25 teeth. Both pinion and gear are
made of C 45 steel. Design a suitable spur gear drives. [AU, May / Jun – 2007]
2.136) In a spur gear drive for a rock crusher, the gears are made of case hardened
alloy steel. The pinion is transmitting 18 kW at 1200 rpm with a gear ratio of
3.5.The gear is to work 8 hours/day for 3 years. Design the drive's major
dimensions, check for compressive and bending stresses and sketch the
arrangement. [AU, May / Jun – 2009]
2.137) In a spur gear drive for a stone crusher, the gears are made of C40 steel. The
pinion is transmitting 20 kW at 1200 rpm. The gear ratio is 3. Gear is to work 8 hrs
per day, six days a week and for 3 years. Design the drive.
[AU, Apr / May – 2011]
2.138) In a spur gear drive for a stone crusher, the gears are made of C45 steel. The
pinion is transmitting 30 kW at 1200 rpm. The gear ratio is 3. Gear is to work 8
hours per day, six days a week and for 3 years. Design the drive.
[AU, Apr / May, Nov / Dec – 2016]
2.139) Design a spur gear drive for a stone crusher where the gears are made of C40
steel. The pinion is transmitting 30 kW at 1200 rpm. The gear ratio is 3. Take the
working life of the gears as 7500 hrs. [AU, Nov / Dec –2014]
2.140) Design a spur gear drive required to transmit 45kW at a pinion speed of
800rpm. The velocity ratio is 3.5:1. The teeth are 20º full depth involute with 18
teeth on the pinion. Both the pinion and gear are made of steel with a maximum

30
safe static stress of 180N/mm2
. Assume medium shock conditions.
[AU, Nov / Dec –2015]
2.141) Design a spur gear drive required to transmit 45kW at a pinion speed of
800rpm. The velocity ratio is 3.5:1. The teeth are 20º full depth involute with 18
teeth on the pinion. Both the pinion and gear are made of steel with a maximum
safe static stress of 180N/mm2
. Assume medium shock conditions. Assume
medium shock conditions, Vm = 12 m/s and steel is hardened to 200 BHN.
[AU, Apr / May – 2017]
2.142) Derive expressions for determining the forces acting on a helical gear.
[AU, Nov / Dec –2012]
2.143) A pair of helical gears subjected to heavy shock loading is to transmit 37.5 kW
at 1750 rpm of the pinion. The speed reduction ratio is 4 and the helix angle is 15o.
The service is continuous and the teeth are 20º full depth in the normal plane.
Select suitable material and design the gears. Check for working stresses and
sketch the drive. [AU, May / Jun – 2009]
2.144) Design a pair of helical gear to transmit 20KW at 1000 rpm of the pinion.
Reduction ratio of 5 is required. Give the details of the drive. Select suitable
materials and stresses. [AU, May / Jun – 2011]
2.145) Design a pair of helical gear to transmit 10 kW at 1000 rpm of the pinion.
Reduction ratio of 5 is required. Pressure angle is 20° and the helix angle is 15°.
The material for both the gears is 40 Ni2Cr 1Mo28. Give the details of the drive in
a tabular form. [AU, Nov / Dec – 2016]
2.146) Design a pair of helical gears to transmit 10 kW at 1000 rpm of the pinion.
Speed ratio 5. Take 40/Ni2 Cr l Mo28 steel as material for pinion and gear. Assume
minimum number of teeth as 20 and tabulate the results. [AU, Nov / Dec – 2017]
2.147) Design a pair of helical gears to transmit 37.5kW at 1750rpm of the pinion.
The drive is subjected to heavy shock loading. The speed reduction ratio is 4 and
helix is 15º. Select suitable material and design the gears. Check for working
stresses and sketch the drive. [AU, May / Jun – 2012]
2.148) Design a helical gear drive to transmit the power of 15kW. Speed ratio is 6.
Pinion speed 1200 rpm, helix angle is 25º. The recommended materials for pinion
and gear are 15Ni2CrlMo15 and C45 steel respectively. [AU, May / Jun – 2012]

31
2.149) Design a helical gear to transmit 15 kW at 1440 rpm to the following
specifications: Speed reduction is 3; pressure angle is 20º; helix angle is 15º; the
material of both the gears is C45 steel. Allowable static stress 180GPa; surface
endurance limit is 800 GPa. Young's modulus of material = 200 GPa.
[AU, Nov / Dec –2013]
2.150) Design a helical gear drive to connect an electric motor to a reciprocating
pump. Gears are overhanging in their shafts. Motor speed = 1440 rpm. Speed
reduction ratio = 5, motor power = 37 kW Pressure angle = 20º Helix angle = 25º.
[AU, Nov / Dec –2014]
2.151) Design a helical gear drive to transmit the power if 14.7kW. Speed ratio 6,
pinion speed 1200rpm, helix angle is 25º. Select suitable materials and design the
gear. [AU, Apr / May – 2015]
2.152) A pair of helical gear subjected to moderate shock loading is to transmit 40KW
at 1440 rpm of the pinion. The speed reduction is 4.25 and the helix angle is 15º.
The service is continuous and teeth are 20º full depth in the normal plane. Design
the gears, assuming life of 10,000 hrs. [AU, Apr / May – 2005]
2.153) Design a pair of full depth involute teeth helical gears to transmit 5kW at
1440rpm. Use C45 steel for the gears. Number of teeth on pinion may be 24 and
that in on gear 56. Check for compressive and bending stresses. Make a simple
sketch and label the important dimensions of the drive. [AU, Nov / Dec –2012]
2.154) A helical gear with 30º helix angle has to transmit 35kW at 1500 rpm with a
speed reduction ratio 2.5. If the pinion has 24 teeth, determine the necessary
module, pitch diameter and face width for 20º full depth teeth. Assume 15 Ni 2 Cr
1 Mo 15 material for both pinion and wheel. [AU, Apr / May – 2008]
2.155) Design a pair of helical gears to transmit 30 KW power at a speed reduction
ratio of 4: 1. The input shaft rotates at 2000 rpm. Take helix and pressure angles
equal to 25º and 25º respectively. The number of teeth on the pinion may be taken
as 30 [AU, Nov / Dec –2005, Apr / May – 2010]
2.156) A pair of helical gears subjected to moderate shock loading is to transmit 37.5
KW at 1750 rpm of the pinion. The speed reduction ratio is 4.25 and the helix
angle is 15º. The service is continuous and the teeth are 20º FD in the normal

32
plane. Design the gears, assuming a life of 10,000 hours.
[AU, Apr / May – 2010, Nov / Dec – 2016]
2.157) For intermittent duty of an elevator, two cylindrical gears made of alloy steel
40 Ni 2 Cr l Mo 28, and have to transmit 12.5 kW at a pinion speed of 1200 rpm.
Design the gear pair for the following specifications: Gear ratio 3.5; Pressure angle
20°, involute full depth, helix anglel5°. Gears are expected to work 6 hours a day
for 10 years. Minimum number of teeth on pinion can be taken as 20 and IS quality
8. [AU, Apr / May – 2017]
2.158) Design a pair of helical gears to transmit 20 KW at a speed reduction ratio of
4:1. The input shaft runs at 2000 rpm. Both pinion and gear are 15 Ni2crl mo15
under carburized condition. [AU, May / Jun – 2007]
2.159) Design a pair of helical gears to transmit 10 kW at 1000 rpm of the pinion.
Reduction ratio of 5 is required. Assume suitable materials and stresses.
[AU, Apr / May – 2011, May / Jun – 2013, Nov / Dec –2015]
2.160) A general purpose enclosed gear train is based on parallel helical gears,
specified life is 36,000 hours. Torque at driven shaft is 411Nm. Driving shaft speed
is 475 rpm. Velocity ratio is 4. It is desired to have standard center distance. Design
the gear drive. [AU, Nov / Dec –2011]
2.161) A pair of helical gears subjected to moderate shock loading is to transmit
30KW at 1500 rpm of the pinion. The speed reduction ratio is 4 and the helix angle
is 20º. The service is continuous and the teeth are 20º FD in normal plane for the
gear life of 10,000 hours, design the gear drive.
[AU, Nov / Dec –2007, Apr / May – 2016]
2.162) A pair of helical gears subjected to moderate shock loading is to transmit 40
kW at 1750 rpm of the pinion. The speed reduction ratio is 4. Design the gear,
assuming a life of 10,000 hours. [AU, Apr / May – 2016]
2.163) A helical gear speed reducer is to be designed. The rated power of the speed
reducer is 75kW at a pinion speed of 1200 rpm. The speed ratio is 3 to 1. For
medium shock conditions and 24 hours operation; determine, the module, face
width, number of teeth in each gear. The teeth are 20º full depth in the normal
plane. Assume suitable materials. [AU, Nov / Dec –2009]

33
2.164) A pair of helical gears is to transmit 14kW. The teeth are 20º stub and helix
angle is 45º. Pinion runs at 10,000 rpm and has 80mm PCD. Wheel has 320mm
PCD. Both gears are made of cast steel. Design the gear pair and obtain the basic
dimensions assuming a life of 1000 hours. [AU, Apr / May – 2010]
2.165) A pair of helical gears subjected to moderate shock loading is to transmit
20kW at 1500 rpm of the pinion. The speed reduction ration is 4 and the helix
angle is 20º. The service is continuous and the teeth are 20º full depth in the normal
plane. For the gear life of 10,000 hours. Design a gear drive.
[AU, Nov / Dec –2010]
2.166) A pair of helical gears is to transmit 12 kW. The teeth ate 20° stub in diametral
plane, and have a helix angle of 45°. The number of teeth on the pinion is 20, and it
runs at 10,000 rpm. The teeth on the gear is 80. If the gears are made of cast steel,
having static strength of 100 MPa; determine the required face width, from the
strength point of view. Assume module as 2 mm and scant lubrication.
[AU, Nov / Dec – 2017]
2.167) A single stage helical gear reducer is to receive power from a 1440 rpm 25 kW
induction motor. The gear tooth profile is involute full depth with 20º normal
pressure angle. The helix angle is 23º, number of teeth on pinion is 20 and the gear
ratio is 3. Both the gears are made of steel with allowable beam stress of 90 MPa
and hardness 250 B.H.N. (i) Design the gears for 20% overload carrying capacity
from the standpoint of bending strength and wear. (ii) If the incremental dynamic
load of 8 kN is estimated in tangential plane, what will be the safe power
transmitted by the pair at the same speed? [AU, May / Jun – 2014]
2.168) The following data is given for a pair of parallel helical gears made of steel,
Speed of pinon= 720 rpm
Number of teeth on pinion = 35
Number of teeth on gear = 70
Centre distance = 285 mm
Normal module = 5 mm
Face width = 50 mm

34
Normal pressure angle = 20º
Ultimate tensile strength = 450 N/mm2
Surface hardness = 300 BHN
Grade of machining = Gr. 8
Factor of safety = 2
Service factor = 1.25
Calculate the
(i) Helix angle (iv) Dynamic load
(ii) Beam strength (v) Maximum static load
(iii) Wear strength (vi) Power transmitting capacity
2.169) In figure given below, a 0.75 KW electric motor runs at 30 rev/s in the
clockwise direction, as viewed from the positive x axis. Keyed to the motor shaft is
an 18 - tooth helical pinion having a normal pressure angle of 20º, a helical angle
of 30º, and a normal module of 2.0 mm. The hand of helix is shown in the figure.
Make a three - dimensional sketch of the motor shaft and pinion, and show the
forces acting on the pinion and the bearing reactions at A and B. The thrust should
be taken out at A.
2.170) Two shafts A and B are connected by skew gears so that A rotates at 2½ times
the speed of B the angle between the shafts is 75º. Wheel A has a pitch diameter of
100mm and has 20 teeth of spiral angle 35º. The teeth on both wheels are of the
same hand. Find the spiral angle of the teeth on B and the distance between the
shafts. Each shaft is provided with a thrust bearing of mean radius 62.5mm; the co-

35
efficient of friction between these and the teeth is 0.05. Find the overall efficiency
of drive if A is the driver and obliquity being neglected.
2.171) A helical cast steel gear with 30o helix angle has to transmit 33.12 KW at 1500
rpm. The gear has 24 teeth. Design the gear for 20ºFD teeth. Static stress for cast
steel may be taken as 56 N/mm2
. Width of face may be taken as three times of
normal pitch gear ratio is 3. Hardness of gear is 250 BHN. (Using Lewis and
2.172) Design a pair of double helical gear to drive a lobe-blower from a 120 KW
motor running at 2880rpm with a reduction ratio of 1.6. The pitch diameter of the
pinion is not to be more than 80 mm. Drive is an enclosed one with proper
lubrication. Life is to be indefinite. Light shock loads are likely.
2.173) Design a Herringbone gear for the data given below; power = 45 KW; pinion
speed =1800 rpm; gear ratio = 4; helix angle = 25º; material used is C 45 steel.
2.174) A power of 40 KW at 1440 rpm is to be transmitted with a gear ratio of 4.
Design a suitable herringbone gear drive.

36
UNIT – III – BEVEL, WORM AND CROSS HELICAL GEARS
PART – A
3.1) What is bevel gear?
3.2) How bevel gears are manufactured? [AU, Apr / May – 2016]
3.3) How are bevel gears classified?
3.4) When do we use bevel gears? [AU, May / Jun – 2007, Apr / May – 2008, 2009]
3.5) When bevel gears are used? [AU, May / Jun – 2007]
3.6) When bevel gear is preferred? [AU, May / Jun – 2009, Nov / Dec –2012]
3.7) Under what situation, bevel gears are used? [AU, Apr / May – 2011]
3.8) Sketch neatly the working drawing of bevel gears in mesh.
3.9) Define back cone radius for a bevel gear. [AU, Nov / Dec – 2016]
3.10) What is a crown gear? [AU, May / Jun – 2011, Nov / Dec – 2016]
3.11) What is the specific feature of a miter gear? [AU, Nov / Dec –2004]
3.12) State whether true or false and justify. Mitre gears are used for connecting non -
intersecting shafts. [AU, Nov / Dec –2005]
3.13) What is meant by Mitre gears? [AU, Nov / Dec – 2017]
3.14) What is virtual number of teeth in bevel gears?
[AU, Apr / May – 2004, May / Jun – 2014, Nov / Dec –2014]
3.15) Define the following terms.(a) pitch angle(b) shaft angle(c) cone
distance(d) face angle [AU, Apr / May – 2005, May / Jun – 2014]
3.16) What is Tredgold's approximation about the formative number of teeth on a
bevel gear?
3.17) What is known as formative number of teeth on bevel gears?
[AU, Apr / May – 2017]
3.18) What are the various forces acting on a bevel gear?
[AU, Nov / Dec –2009, May / Jun – 2013]
3.19) What is a Zerol bevel gears? [AU, Apr / May – 2015]
3.20) Write a note on beam strength of a bevel gear
3.21) What do you mean by angular bevel gear?
3.22) What is the difference between an angular gear and a miter gear?
[AU, Nov / Dec –2012, 2013, 2015]

37
3.23) Specify the features of skew bevel gears. [AU, May / Jun – 2012]
3.24) State the difference between internal and external bevel gear.
3.25) Differentiate a straight bevel gear and a spiral bevel gear.
[AU, Apr / May – 2016]
3.26) Mention two characteristics of hypoid gear. [AU, Apr / May – 2010]
3.27) If the radial force component of the bevel gear is 1200N (+ y direction),
determine the axial component of pinion in the gear drive. Also write down the
relation between the axial force and tangential force component.
[AU, Nov / Dec –2010]
3.28) What is Lewis (tooth) form factor? [AU, Apr / May – 2010]
3.29) What is reference angle? How is it related to speed ratio of bevel gear ratio?
[AU, May / Jun – 2012]
3.30) State the assumption used in the estimation of equivalent number of teeth for
bevel gear using Tredgold’s approximation.
3.31) What is a worm - gear drive?
3.32) What kind of contact occurs between worm and wheel? How does it differ from
other gears? [AU, Nov / Dec –2015]
3.33) Suggest the suitable gear for the following application. i) A hand operated
winch to have speed ratio of 50: 1 ii) Differential gear mechanism in automobile.
[AU, Nov / Dec – 2017]
3.34) How does worm gear differ from other gears?
3.35) What are the commonly used materials for worm and wheel?
[AU, May / Jun – 2007]
3.36) Why phosphor bronze is widely used for worm gears? [AU, Nov / Dec –2013]
3.37) When do we use worm gears? [AU, May / Jun – 2013]
3.38) Under what circumstances, the worm gears are used for power transmission?
[AU, Nov / Dec – 2017]
3.39) Give some applications of worm - gear drive. [AU, May / Jun – 2007]
3.40) Write some applications of worm-gear drive. [AU, Nov / Dec – 2016]
3.41) In worm gear drive, only the wheel is designed. Why? [AU, Apr / May – 2011]
3.42) Mention the reason for irreversibility in worm gears. [AU, Nov / Dec –2010]
3.43) Define the following terms (a) pitch (b) lead

38
3.44) Write the conditions of self-locking of worm gears in terms of lead and Pressure
angles. [AU, Apr / May – 2017]
3.45) What are the various forces acting on worm and worm gears?
3.46) Write the expression for centre distance in terms of axial lead, lead angle and
velocity ratio.
3.47) What is helical angle of worm? [AU, Apr / May – 2016]
3.48) Give the speed ratio range of worm – wheel drive. [AU, May / Jun – 2012]
3.49) Usually worm is made of hard materials and worm gear is made of softer
material – Justify. [AU, Nov / Dec –2009]
3.50) Why is dynamic loading rarely considered in worm gear drives?
[AU, Nov / Dec –2011]
3.51) In which gear – drive is self – locking available?
[AU, Nov / Dec –2008, Apr / May – 2015]
3.52) Why is a multistart worm more efficient than a single start one?
[AU, Nov / Dec – 2005]
3.53) When the number of start of a worm is increased in a worm gear drive, how it
affects the other parameters and action of the drive? [AU, Apr / May – 2004]
3.54) Write the advantages of worm gear drive. [AU, May / Jun – 2008]
3.55) Mention the advantages of worm gear drive. [AU, Nov / Dec –2014]
3.56) What are the disadvantages of worm gear drive? [AU, Nov / Dec – 2017]
3.57) Write some applications of worm gear drive. [AU, May / Jun – 2011]
3.58) State the advantage of worm gear drive in weight lifting machines.
[AU, Apr / May – 2008]
3.59) What are the main types of failure in worm gear drives?
[AU, May / Jun – 2012, Nov / Dec –2012]
3.60) What are the two types of failure in worm gear drives? [AU, Nov / Dec – 2016]
3.61) Define normal pitch of a worm gear. [AU, Apr / May – 2016]
3.62) How do you rate the strength of worm gears?
3.63) A pair of worm gears is designated as 2 / 54 / 10 / 5. Find the gear ratio.
[AU, Nov / Dec –2010]
3.64) State the factors which reduce the efficiency of the worm gear.

39
3.65) Why is the efficiency of a worm gear drive comparatively low?
[AU, Apr / May – 2004, Nov / Dec –2007]
3.66) How do you specify a worm gear pair?
3.67) Differentiate cross helical from parallel axis helical gear.
3.68) Write the relationship between the shaft angle and the helix angles of mating
gears 1 and 2with respect to cross helical gear.
3.69) When do we employ crossed helical gear? [AU, Apr / May – 2010]
3.70) Why is the crossed helical gear drive not used for power transmission?
[AU, Nov / Dec –2007]
3.71) Calculate the angle between the shafts of a crossed helical gears made of two
right handed helical gears of 15º helix angle each. [AU, May / Jun – 2009]
3.72) Calculate the angle between the shafts of a crossed helical gears made of two left
handed helical gears of 10º helix angle each. [AU, Nov / Dec –2012]
PART – B
3.73) Discuss in detail about the design procedure of bevel gear drive.
3.74) Derive expressions for determining the forces acting on a bevel gear with
suitable illustrations. [AU, Nov / Dec –2014]
3.75) Design a bevel gear drive to transmit 7 KW at 1600 rpm for the following data :
Gear ratio = 3
Material for pinion and gear = C45 steel
Life = 10,000 hrs.
[AU, May / Jun – 2013, Apr / May – 2016]
3.76) Design the teeth of a pair of bevel gears to transmit 18.75 KW at 600 rpm of the
pinion. The velocity ratio should be about 3 and the pinion should have about 20
teeth which are full depth 20º involute. Find the module, face width, diameter of
the gears and pitch cone angle for both gears. [AU, Nov / Dec –2005, 2008]
3.77) Two straight bevel gears are used in a speed reducer with a transmission ratio of
2. The wheel is supported on both sides and the pinion is over hanging. The input is
from a 2 KW electric motor running at 950 rpm. Design the bevel gears.
[AU, May / Jun – 2012]

40
3.78) A pair of straight bevel gear is to be designed to transmit 5 KW at a pinion speed
of 800 rpm. The desired velocity ratio is 2. Choosing proper materials, design the
drive.
3.79) Design a pair of spiral bevel gear for the following details :
Velocity ratio = 3
Power permitted = 20 KW
Speed of pinion = 600 rpm.
3.80) A pair of bevel gear is required to transmit 30 KW at 500 rpm. The output shaft
is running at 200 rpm and is at right angles to the input shaft. The gear is of cast-
iron and the pinion is of cast steel. Determine the properties of the gears on the
basis of strength.
3.81) A pair of bevel gears is to be used to transmit 12 KW from a pinion rotating at
360 rpm to a gear mounted on a shaft which intersects the pinion shaft at an angle
of 70º. Assuming that the pinion is to have an outside pitch diameter of 200 mm, a
pressure angle of 20º, a face width of 40 mm, and the gear shaft is to rotate at 120
rpm, determine the(i)pitch angle for the gears(ii)forces on the gears(iii)torque
produced about the shaft axis. [AU, Nov / Dec –2004]
3.82) A pair of bevel gears with 20° pressure angle consists of 20 teeth pinion meshing
with a 40 teeth gear. The module is 4 mm and face width is 20 mm. The static
strength of the steel used for the pinion and gear is 200 MPa. The Pinon rotates at
500 rpm and receives power from an electric motor. Determine the rated power that
the gears can transmit from the strength point of view. Assume generated teeth.
[AU, Nov / Dec – 2017]
3.83) A pair of straight tooth bevel gears has a velocity ratio of 4/3.The pitch diameter
of the pinion is 150 mm. The face width is 50 mm. The pinion rotates at 240 rev /
min. The teeth are 5mm module, involute. If 6 KW is transmitted, determine (i) the
tangential force at the mean radius (ii) the pinion thrust force (iii) the gear thrust
force. Draw the free body diagrams indicating the forces. [AU, Apr / May – 2005]
3.84) A pair of 20º FD involute bevel gear connect shafts at right angle having velocity
ratio 3:1. Gear is made of cast steel having allowable static strength of 70
N/mm2
and the pinion is of steel with allowable static stress as N/mm2
and the pinion

41
transmits 36.8KW at 750 rpm. Design the drive (Using Lewis and Buckingham
equation).
3.85) A micarta pinion at 1200 rpm is to transmit 1kW at a cast iron gear at a speed of
192 rpm. Assuming a starting overload of 20% and using 20º full depth involute
teeth, determine the module, number of teeth on the pinion and gear and face
width. Take allowance static strength for micarta as 40MPa and for cast iron as
53MPa. Check the pair in wear. [AU, Nov / Dec –2008]
3.86) Design a pair of bevel gears for two shafts whose axis are at right angles. The
power transmitted is 25 KW. The speed of the pinion is 300 rpm and of the gear is
120 rpm. [AU, May / Jun – 2006]
3.87) Design a pair of bevel gears for two shafts whose axes are at right angles. The
power transmitted is 25 KW. The speed of the pinion is 300 rpm and the gear in
120 rpm. [AU, May / Jun – 2007]
3.88) Design a pair of bevel gears for two shafts whose axis are at right angles. The
power transmitted is 30KW. The speed of the pinion is 300 rpm and of the gear is
120 rpm. Select the materials and design the drive. [AU, Apr / May – 2004]
3.89) Design a pair of cast iron bevel gears for a special purpose machine tool to
transmit 3.5kW from the shaft at 500rpm to another at 800rpm. The gears overhang
in their shafts. Life required is 8000 hours. [AU, Apr / May – 2010]
3.90) A pair of straight bevel gears is mounted on shafts, which are intersecting at
right angles. The pinion shaft is connected to an electric motor developing 16.5
KW at 500 rpm. The gear should run at 200 rpm. Design the drive.
[AU, May / Jun – 2007]
3.91) A 90º degree straight bevel gear set is needed to give a 3:1 reduction. Determine
the pitch cone angle, pitch diameter and gear forces if the, 25 degree pressure angle
has 15 teeth of pitch circle diameter, 4 and the power transmitted is 8 HP at 550
pinion rpm. [AU, May / Jun – 2007]
3.92) Design a bevel gear drive to transmit 3.5 KW with the following specifications:
Speed ratio = 4; driving shaft speed = 200 rpm; drive is non-reversible; material for
pinion is steel; material for wheel is cast iron; and life 25,000 hrs.
[AU, Nov / Dec –2007, 2011, 2016, Apr / May – 2016]

42
3.93) Design a bevel gear drive to transmit 3.5 kW. Speed ratio = 4. Driving shaft
speed= 200 rpm. Pinion is of steel and wheel of CI. Assume a life of 25000 hrs.
[AU, Nov / Dec – 2016]
3.94) Design a bevel gear drive to transmit 10kW at 1600rpm for the following data:
Gear ratio = 3; Materials for pinion and gear = C45steel; Life = 10,000 hours.
[AU, May / Jun – 2011]
3.95) Design a bevel gear drive to transmit 7.5kW. Speed ratio is 4. Driving shaft
speed 400 rpm. [AU, Nov / Dec –2012]
3.96) Design a bevel gear drive to transmit 7.36 kW at 1440 rpm for the following
data. Gear ratio 3, material for pinion and gear C45 surface hardened.
[AU, Nov / Dec – 2017]
3.97) Design a straight bevel gear drive between two shafts at right angles to each
other to transmit 4kW. Speed of the pinion shaft is 300rpm and the speed of the
gear wheel shaft is 900rpm. Pinion is of steel and wheel of cast iron. Assume the
expected gear life as 20,000hours. [AU, Nov / Dec –2012]
3.98) Design a straight bevel gear drive between two shafts at right angles to each
other. Speed of the pinion shaft is 360 rpm and the speed of the gear wheel shaft is
120 rpm. Pinion is of steel and wheel of cast iron. Each gear is expected to work 2
hours per day for 10 years. The drive transmits 9.37 kW.
[AU, Nov / Dec –2013, 2015]
3.99) Design a pair of straight bevel gears for two shafts whose axis are right angles.
The power transmitted is 25kW. The speed of pinion is 300rpm and of the gear is
120rpm. [AU, Apr / May – 2015]
3.100) A 25 kW motor running at 1200 rpm drives a compressor at 780 rpm through a
90º bevel gearing arrangement. The pinion has 30 teeth. The pressure angle of the
teeth is 20º. Both the pinion and the gear are made of heat treated cast iron grade
35. Determine the cone distance, average module and face width of the gears.
[AU, Apr / May – 2008]
3.101) Design a bevel gear drive to transmit 10 kW at 1440 rpm. Gear ratio is 3,
material for pinion and gear is C45 steel. Minimum number of teeth is to be 20.
[AU, May / Jun – 2009, 2014]

43
3.102) Design a bevel gear drive to transmit 7.36 kW at 1440 rpm for the following
data. Gear ratio = 3. Material for pinion and gear C45 surface hardened.
[AU, Apr / May – 2011]
3.103) Design a bevel gear drive to transmit 7.5kW at 1500rpm. Gear ratio is 3.5.
Material for pinion gear is C45 steel. Minimum number of teeth is to be 25.
[AU, May / Jun – 2012]
3.104) Design a bevel gear drive to transmit 7.5 kW at 1440 rpm: Gear ratio 3. Pinion
and gear are made of forged C45 steel. Life of gears 10,000 hrs. Assume surface
hardened heat treatment and IS quality 6. [AU, Apr / May – 2017]
3.105) A pair of cast iron bevel gears connect two shafts at right angles. The pitch
diameters of the pinion and gear are 80mm and 100mm respectively. The tooth
profiles of the gears are 14.5 º composite forms. The allowable static stress for both
the gears is 55MPa. If the pinion transmits 2.75kW at 1100rpm, find the module
and number of teeth on each gear and check the design. Take surface endurance
limit as 630MPa and module and modulus of elasticity for cast iron as 84kN/mm2
.
[AU, Nov / Dec –2009]
3.106) Design a cast iron bevel gear drive for pillar drilling machine to transmit
1.5kW at 800 rpm to a spindle at 400 rpm. The gear is to work for 40 hours per
week for 3 years. Pressure angle is 20º. Check the design and calculate the basic
dimensions. [AU, Nov / Dec –2010]
3.107) The input to worm gear shaft is 18 KW and 600 rpm. Speed ratio is 20, the
worm is of hardened steel and the wheel is made of chilled phosphor bronze.
Considering wear and strength, design worm and worm wheel.
[AU, May / Jun – 2011, Nov / Dec –2013, 2015]
3.108) Determine the dimensions of a pair of worm and worm wheel for transmitting
25KW at a worm speed of 1200 rpm. The desired ratio is about 12. Choosing
proper materials decide all the dimensions.
3.109) A worm gear drive is required to give a reduction ratio of 20 + 2%. Power to be
transmitted is 10 KW, at 1440 rpm of the pinion speed. Use steel worm and bronze
wheel with suitably assumed stress values.
3.110) A 2 kW power is applied to a worm shaft at 720 rpm. The worm is of
quadruple start type with 50 mm as pitch circle diameter. The worm gear has 40

44
teeth with 5 mm module. The pressure angle in the diametral plane is 20º.
Determine the (i) lead angle of the worm, (ii) velocity ratio, and (iii) centre
distance. Also, calculate the efficiency of the worm gear drive, and power lost in
friction. [AU, Apr / May – 2008, May / Jun – 2014, Nov / Dec – 2017]
3.111) Design a worm - gear speed reducer for transmitting 6 KW at 960 rpm of the
worm with a transmission ratio of 15. Allowable variation of ratio is + 3%. Load
almost constant. Rating is continuous. Reducer is used to operate a transporter in a
furnace which is to work for 2 shift / day, 310 days per year and for 2 years.
3.112) A hardened steel worm rotates at 1440 rpm and transmits 11 kW to a phosphor
bronze gear with a gear ratio of 15. Design the worm gear drive and determine the
power loss by heat generation. [AU, May / Jun – 2009]
bronze gear. The speed of the worm wheel should be 60 ± 3% rpm. Design the
worm gear drive if an efficiency of at least 82% is desired.
[AU, Nov / Dec –2010, 2014]
bronze gear. The speed of the worm gear should be 60 rpm. Design the worm gear
drive if an efficiency of at least 82% is desired. [AU, Nov / Dec – 2016]
3.115) Design a worm gear reducer to transmit 10 hp from the input shaft running at
1800 rpm to the output shaft which is to run at 100 rpm. Calculate the efficiency of
the drive.
3.116) Design a worm gear drive to transmit 12 kW at 1440 rpm with a speed ratio of
20. Use steel worm and cast iron wheel. [AU, Nov / Dec –2012]
3.117) Design a worm gear drive to transmit 10 kW at 1440 rpm with a speed ratio of
12. Use steel worm and cast steel wheel. [AU, Nov / Dec –2012]
3.118) Design a worm gear drive with a standard centre distance to transmit 7.5 KW
from a worm rotating at 1440 rpm to a worm wheel at 20 rpm.
[AU, Apr / May – 2005, 2010, Nov / Dec –2008]
3.119) A speed reducer wait is to be designed for an input of 11.25 KW with a
transmission ratio of 20. The speed of the hardened steel worm is 1500 rpm. The
worm wheel is to be made of bronze. The tooth form is to be 20º involute.
[AU, Nov / Dec –2005]

45
3.120) Design a worm gear drive to transmit 18KW at a worm speed of 1440 rpm.
Speed ratio is 24. A minimum required efficiency of the drive 85%. Check the
design for heat dissipation and give your interference. [AU, Apr / May – 2004]
3.121) Design a worm gear drive to transmit 22.5 KW at a worm speed of 1440 rpm.
Velocity ratio is 24:1. An efficiency of at least 85% is desired. The temperature rise
should be restricted to 40ºC. Determine the required cooling area. [AU,
May / Jun – 2006, 2007, 2013, Nov / Dec –2004, 2011, 2017, Apr / May – 2015]
3.122) Design a worm gear drive to transmit 22 KW at a worm speed of 1440 rpm.
Velocity ratio is 24:1. An efficiency of at least 85% is desired. Assume that the
worm is made of hardened steel and the gear of phosphor bronze. Take the centre
distance as 100mm. [AU, Nov / Dec –2009]
3.123) Design a worm gear drive to transmit 18KW at a worm speed of 600 rpm.
Speed ratio is 20. Assume that the worm is made of hardened steel and the wheel of
phosphor bronze [AU, May / Jun – 2012]
3.124) Design a worm drive for a speed reducer to transmit 15 kW at 1440 rpm of the
worm shaft. The desired wheel speed is 6 rpm. Select suitable worm and wheel
materials. [AU, Apr / May – 2011]
3.125) Design a worm gear drive and determine the power loss by heat generation.
The hardened steel worm rotates at 1500rpm and transmits 10kW to phosphor
bronze gear with gear ratio of 16. [AU, May / Jun – 2012]
3.126) A worm drive transmits 15 KW at 2000 rpm to a machine carriage at 75 rpm.
The worm is triple threaded and has 65 mm pitch diameter. The working gear has
90 teeth of 6 mm module. The tooth form is to be 20º full depth involute. The co -
efficient of friction between the mating teeth may be taken as 0.10. Calculate the
(i) Tangential forces acting on the worm
(ii) Axial thrust and separating force on the worm
(iii) Efficiency of worm drive.
3.127) Design a worm gear speed reducer to transmit 22 KW at worm speed of 1440
rpm. Velocity ratio is 24:1. An efficiency of 81% is desired. The temperature rise is
to be restricted to 40ºC Determine the required cooling area, assuming that worm is

46
made of hardened steel and gear of phosphor bronze (Using Lewis and
3.128) Design a worm gear drive for the following data: Power to be transmitted: 20
KW, worm speed: 1440 rpm, speed reduction: 24:1. [AU, Apr / May – 2007]
3.129) Design a worm gear drive to transmit 20 kW at 1440 rpm speed of worm wheel
is 60rpm. [AU, Apr / May – 2016]
3.130) Design a worm gear drive to transmit a power 22.5 KW. The worm speed is
1440 rpm and the speed of the wheel is 60rpm. The drive should have a minimum
efficiency of 80% and above. Select suitable materials for the worm and wheel and
decide upon the dimensions of the drive. [AU, Nov / Dec –2007]
3.131) Design a worm gear drive to transmit 20 HP from a worm at 1440 rpm to the
worm wheel. Assume the bronze is sand chill cast. The speed of the wheel should
be 40 ± 2% rpm, initial sliding velocity can be assumed as 3 in/sand efficiency as
80%. [AU, Apr / May – 2017]
3.132) A steel worm running at 240 rpm receives 1.5 kW from its shaft. The speed
reduction is 10:1. Design the drive so as to have an efficiency of 80.1. Also
determine the cooling area required, if the temperature rise is restricted to 45 °C.
Take overall heat transfer coefficient as 10 W/m2
°C. [AU, Apr / May – 2016]
3.133) Suggest a suitable design for a pair of cross helical gears to transmit 100 HP
between a 2400 rpm electric motor and an 800 rpm load that is essentially free of
shock. Forty - hour -week operation is anticipated. State a satisfactory combination
of pitch, number of teeth, helix angle, pressure angle, face width, manufacturing
accuracy and material hardness.

47
UNIT – IV – GEAR BOXES
PART – A
4.1) What is a gear box?
4.2) What purpose does the housing of a gear - box serve?
4.3) What is the function of spacers in a gear - box?
[AU, Nov / Dec –2004, 2008, Apr / May – 2005, May / Jun – 2011]
4.4) Specify four types of gearboxes. [AU, Nov / Dec –2014]
4.5) What is a speed diagram?
4.6) What is multispeed gear box? [AU, Apr / May – 2016]
4.7) Name the series in which speeds of multi - speed gear box are arranged.
[AU, May / Jun – 2007, 2011]
4.8) What is R20 series? [AU, Apr / May – 2016]
4.9) What are preferred numbers?
[AU, Apr / May – 2011, 2016, Nov / Dec –2012, 2014, May / Jun – 2013]
4.10) Discuss the uses of speed diagram.
4.11) For what purpose are gear - box used?
4.12) What are the main components of a gear - box?
4.13) What is meant by speed reducers?
4.14) Name the types of speed reducers
4.15) Classify speed reducers. [AU, Nov / Dec –2012]
4.16) What are the methods of lubrication in speed reducers?
[AU, Nov / Dec –2004, 2011]
4.17) What does the ray - diagram of a gear - box indicate? [AU, May / Jun – 2012]
4.18) What is meant by ray diagrams? [AU, Apr / May – 2010, May / Jun – 2012]
4.19) Write the significance of structural formula. [AU, Nov / Dec –2015]
4.20) Differentiate ray diagram and structural diagram. [AU, Nov / Dec –2007, 2016]
4.21) Distinguish between structural diagram and speed diagram.
[AU, Nov / Dec –2011]
4.22) What is step ratio? [AU, May / Jun – 2007, Nov / Dec –2013, 2016]
4.23) What is step ratio in gear box? [AU, May / Jun – 2012]

48
4.24) What is step ratio? Name the series in which speeds of multi-speed gear box are
arranged. [AU, May / Jun – 2014]
4.25) Define geometric progression. [AU, Apr / May – 2010]
4.26) Explain the ray diagram and list the advantages of geometric progression.
[AU, Apr / May – 2004]
4.27) What is the purpose of the ray diagram in designing the gearbox?
[AU, Nov / Dec – 2017]
4.28) Why geometric progression is selected for arranging the speeds in gear boxes?
[AU, Apr / May – 2017]
4.29) Define progression ratio. [AU, Nov / Dec –2015]
4.30) List any two methods used for changing speeds in gear boxes.
[AU, Nov / Dec – 2016]
4.31) List the ways by which the number of intermediate steps may be arranged in a
gear box. [AU, Apr / May – 2010]
4.32) What are the possible arrangements to achieve 12 speeds from a gear box?
[AU, Apr / May – 2011, May / Jun – 2013, Nov / Dec – 2016]
4.33) What are the possible arrangements to achieve 16 speeds from a gear box?
Which is the preferred arrangement? [AU, Nov / Dec –2010]
4.34) Sketch the kinematic layout of gears for 3 speeds between two shafts.
[AU, Apr / May – 2008, May / Jun – 2014]
4.35) List six standard speeds starting from 18 rpm with a step ratio 1.4.
[AU, Apr / May – 2008]
4.36) Calculate standard step ratio for six speed gear with speed ranging between 100
and 560 rpm. [AU, Nov / Dec –2012]
4.37) What does the ray diagram of gear box indicates?
[AU, Nov / Dec –2010, May / Jun – 2011, Apr / May – 2017]
4.38) Draw the ray diagram for a six speed gear box
[AU, May / Jun – 2006, 2007, Apr / May – 2015]
4.39) Draw the ray diagram for 12 speed gear box. [AU, Nov / Dec – 2017]
4.40) State the importance of kinematic arrangement of gears in a gear box.
4.41) Differentiate speed diagram from kinematic arrangement of gears.
4.42) What is the recommended speed ratio between two shafts in a gear box design?

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