DHAANISH AHMED INSTITUTE OF

TECHNOLOGY
DEPARTMENT OF MECHANICAL ENGINEERING

ME 8651- DESIGN OF TRANSMISSION SYSTEM

QUESTION BANK

SEMESTER-6
UNIT – I DESIGN OF FLEXIBLE ELEMENTS

Part A
1. List the advantages of flat belt drives? (R)
a. Low initial cost
b. Noiseless
c. Drive is protected overloads
d. Connecting shafts are large centre distance apart

2. Classify the types of transmission belts. (U)

a. Flat belts
b. V – belt
c. Circular belt

3. Formula to be use the equation for calculating the length of the belt for
open and crossed belt drives. (C)

Open belt drive:

Crossed belt drive:

4. Define law of belting. (R)

The centre of the approaching belt must be perpendicular to the plane of the
pulley

5. How the belt drives are selected? (E)

a. Power to be transmitted.
b. Centre distance between two shafts
c. Service conditions
d. Speed reduction ratio
 e. Speed of driver and driven shaft.
6. State reason for V-belt drives being preferred to flat belt drive. (R)
a. Replacement of V-belt is easy.
b. Power transmitted by the V-belt is more.
c. For smaller centre distance V-belts are more suitable.
d. Efficiency is high when compared to flat belt.

7. Define V-flat drives? (R)

In V-belt drives, if the large grooved pulley is replaced by a flat faced pulley, then the
drive is known as V-flat drives

8. Classify the different types of V-belts? (U)

According to the Indian Standards, the V-belts are five types, i.e, A, B, C, D, and E

9. Identify the materials used for V- grooved pulleys? (U)

a. Cast Iron
b. Pressed Steel
c. Die cast Aluminum
d. Forged Steel

10.Examine the factors affecting the belt life? (AN)

a. Decrease in small pulley diameter
b. Increase in belt thickness
c. Increase in tight side tension
d. Too large centre distance

11.Identify the factors affecting the coefficient of friction between a belt

and pulley? (U)
The coefficient of friction between the belt and pulley depends upon the factors like belt
material, pulley material, slip of the belt and speed of the belt. The coefficient of friction
lies between 0.25 to 0.3

12. Examin the losses in belt drives? (AN)

The losses in a belt drive are due to:
a. Slip and creep of the belt on the pulleys,
b. Wind age or sir resistance to the movement of belt and pulleys.
c. Bending of the belt over the the pulleys and
d. Friction in the bearings of pulley.

13.When do you Select to prefer a rope drive? (E)

 Wire ropes are preferred whenever large power is to be transmitted over long
distance upto 150m

14.List the applications used in wire ropes. (R)

a. Elevators
b. Mine hoist
c. Cranes
d. Conveyors

15.How the wire ropes are designated? (C)

The wire ropes are designed by a number
a. Specify the number of strands and number of wires in each strand
b. Wire diameter
c. Wire material grade
d. Construction type

16.What do you understand by 6x19 constructions of wire ropes? (U)

6- Number of strands in wire rope
19- Number of wires in each strand

17.List the advantages of wire ropes? (R)

a. It is lighter in weight
b. Withstand shock loads
c. Silent operation
d. Does not fail suddenly
e. Efficiency is high
18.List out the various stress induced in the wire ropes. (R)
a. Direct stress due to the weight of the load to be lifted and weight of the load
b. Bending stress when the rope passes over the sheave
c. Stress due to acceleration
d. Stress during starting stopping
19.List the advantages of chain drives? (R)
a. Compact drive as compared to flat belt drive.
b. No slip between sprocket and chain.
c. High efficiency of the drive.
20.List the failures in chain drives? (R)
a. Elongation
b. Failure in joints and plates
c. Wear of the sprocket teeth
21.List the different types of chains? (R)
a. Link(or welded load) chains,
b. Transmission (or roller) chains
c. Silent (or inverted tooth) chains.
22. Schedule the applications of link (or hoisting) chains? (A)
Link (or hoisting) chains are widely used
 a. In low capacity machines such as hoists, winches and hand operated cranes
as the main lifting appliances, an
b. As slings for suspending the load from hook or other device.
23.Explain silent chain? In what situations, silent chains are preferred?
(AN)
a. Inverted tooth chains are called silent chains because of their relatively quiet
operation.
b. Silent Drives are preferred for high-power, high-speed, and smooth operation.

24. Schedule applications of chain drives. (A)

a. Transportation industry
b. Agricultural machinery
c. Metal and wood working machines
25.What are the commonly used belt materials? (A)
a. Leather
b. Cotton or Canvas
c. Rubber
d. Nylon core belts
e. Balata belts

PART B
1. It is required to select a flat belt drive for a fan running at 360r.p.m
which is driven by a 10kW, 1440r.p.m motor. The belt drive is open
type and space available for a centre distance of 2m approximately. The
diameter of a driven pulley is 1000mm. (C)
2. An open belt drive connects two parallel shafts 1.2m apart. The driving
and driven shafts rotate at 350 r.p.m and 140 r.p.m respectively and the
driven pulley is 400mm in diameter. The power to be transmitted is
1.1kW. Design the drive. (C)
3. Design a belt drive to transmit 20kW at 720r.p.m to an aluminum
rolling machine, the speed ratio being 3. The distance between the
pulleys is 3m. diameter of the rolling machine pulley is 1.2m
(C)
4. A flat belt is required to transmit 35kW from a pulley of 1.5m effective
diameter running at 300r.p.m. The angle of lap is 165 degree and
 coefficient of friction is 0.3. Determine taking centrifugal tension into
account, width of the belt is required. It is given that the belt thickness
is 9.5mm, density of the material is 1.1 Mg/m^3 and the related
permissible working stress is 2.5MPa. (C)
5. In a crossed belt drive, the belt has 6mm thick, transmits 7.5kW and
operates at a velocity of 13m/s approximately. The coefficient of friction
is 0.3 and permissible tensile stress for the belt material is 1.75N/mm^2.
The density of leather is 0.95gm/cc. Calculate a) diameter of the pulleys
b) length and width of the belt c) belt tension in tight and slack side.
Take length of the belt is 1% less to give initial tension.
(C)
6. Design a V-belt and calculate the actual belt tensions and average stress
for the following data. D=500mm, d=150mm, C=925mm, N1=1000r.p.m,
N2=300r.p.m and P=7.5kW . (C)
7. Design a V-Belt drive to the following specifications
Power to be transmitted =7.5kW

Speed of the driving wheel = 1440r.p.m

Speed of the driven wheel = 1440r.p.m

Diameter of driving wheel = 300mm

Center distance = 1000mm

Service = 16 hours / day (C)

8. A centrifugal pump running at 340r.p.m is to be driven by a 100kW

motor running at 1440r.p.m. The drive is to work for at least 20 hours
every day. The center distance between the motor shaft and the pump
 shaft is 1200mm. suggest a suitable multiple V- belt drive for this
application. Also calculate actual belt tension and stress induced.
(C

9. Two shafts whose center distance is 1m apart are connected by a V- belt

drive. The driving pulley is supplied with 100kW and has an effective
diameter of 300mm. it runs at 1000rom while the driven pulley runs at
375r.p.m. The angle of groove on the pulley is 40 degree. The
permissible tension in 400mm^2 cross sectional area of belt is 2.1MPa.
The density of the belt is 1100kg/m^3. Taking coefficient of friction is
0.28, estimate the number of belts required. Also calculate the length
required of each belt.
(C)

UNIT II
1. Explain the advantages of gear drive? (AN)
a. There is no slip
b. Capable of transmitting large power
c. Efficiency is high

2. Define transmission ratio with reference to spur gear. (R)

The ratio of speed of the driving gear to the speed of the driven gear

3. Explain addendum value more than addendum value? (AN)

The dedendum value is more than the addendum value to provide the necessary
clearance between the gears while meshing.

4. What are the factor influence backlashes in gear drives? (A)

a. Module
b. Pitch line velocity

5. Define backlash? (R)

The difference between the tooth space and tooth thickness along the pitch
circle.
 Backlash = tooth space – tooth thickness

6. What are the classifications of gears based on peripheral velocity? (U)

a. Low velocity gears= less than 3m/s
b. Medium velocity gears=3m/s to 15m/s
c. High velocity gears= greater than 15m/s
7. Define pressure angle? ( R)
The angle between the common normal to two gear teeth at the point of contact
and common tangent to the pitch point is called as pressure angle.

8. “AGMA” stands for what? (R)

American Gear Manufacturing Association

9. What are the materials used for gear manufacturing? (A)

Metallic gears: Steel, Cast Iron, Bronze
Non Metallic gears: Wood, Compressed paper and Synthetic resin

10.List out the various methods of manufacturing a gear. (R)

1) Gear milling
2) Gear Molding
a. Injection molding
b. Die casting
c. Investment casting
3) Gear Generating
a. Gear hobbing
b. Gear shaping
11.Who do you relate helical gears than spur gears? (A)
a. Produce less noise than spur gear
b. Greater load capacity than equivalent spur gears
12.Differentiate Double helical gear and Herringbone gears. (AN)

Double Helical gear Herringbone gears

1. When there is groove between When there is no groove between the

the gears gears

13.Explain the helix angle of the herringbone gears? (AN)

 The helix angle of the herringbone gear ranges from 250 to 400

14.Explain the demerits of the helical gear? (AN)

a. The axial thrust is produced
b. Machining of gear is difficult and costly
c. Complicated design

15.Explain virtual number of teeth in the helical gear? (AN)

The number of teeth on the virtual spur gear in the normal plane is known as
virtual number of teeth

16.Explain the assumptions made in deriving Lewis equation? (AN)

a. Effect of radial component.
b. Tangential force is applied to the tip of a single tooth.
c. Stress concentration in the tooth fillet is negligible.

17.A pair of helical gears consists of a 20 teeth pinion meshing with a 70

teeth gear. The normal module is 3mm. Find the required value of the
helix angle if the center distance is exactly 150mm (C)
18.A pair of spur gear working at 8 hours per shift, 5 days per week for 2
years. Calculate the gear life if the speed of the pinion is 1400 rpm (C)

19.Write the equation for induced contact stress for spur and helical gears
(C)

Spur gear:
Helical gear:

20.A pair of spur gear with a centre distance of 495mm is used for a speed
reduction of 45:1. The module is 6mm. calculate the number of teeth on
the pinion and gear. (C)
PART B

1. A motor shaft rotating 1440 r.p.m has to transmit 15kW power at a low
speed shaft rotating at 500 r.p.m. A 200 pressure angle involutes tooth
gear pinion is used. The pinion has 25 teeth. Design a suitable gear derive
(C)
2. Design a spur gear drive to transmit 22.5kW at 900 r.p.m. Speed reduction
is 2.5. Materials for pinion and wheel are C15 steel and Cast iron grade 30
 respectively. Take pressure angle of 200 and working life of gears are
10,000 hrs.(C)
3. Design a pair of spur gear drive to transmit 30kW at 1440 r.p.m. Speed
reduction is 2.5. Assume all the data. (C)
4. Write the design procedure for the Helical gear. (C)
5. Design a pair of helical gear to transmit 30 kW at a speed reduction ratio
of 4:1. The input shaft runs at 200 r.p.m. Both pinion and wheel are 15Ni
2Crl Mo15 under carburized condition and the helix angle is 150. (C)
6. A pair of helical gears subjected to moderate shock loading is to transmit
30kW at 1500 r.p.m of the pinion. The speed reduction ratio is 4 and the
helix angle is 200. The service is continuous. For the gear life 10,000 hrs.
Design a gear drive. (C)
7. A compressor running at 360 r.p.m is driven by a 140kW, 1440 r.p.m
motor through a pair of 20 degree full depth helical gears having helix
angle of 250. The center distance is approximately 400mm. The motor
pinion is to be forged steel and the driven gear is to be cast steel. Design a
pair of gear drive (C)
8. Design a pair of helical gears to transmit 38kW at 1500 r.p.m. The speed
reduction ratio is to be 5 and the helix angle is 220. Assume all data.
(C)
9. A helical gear speed up drive is required to drive a centrifugal compressor
running at 3000 r.p.m. The helical gear speed up unit is driven by an
electric motor running at 1000 r.p.m. The compressor requires a nominal
input power of 12.5kW. The helix angle is 250 may be assumed for the
gears. Standard involutes profile 20 degree full depth system will be used
 for the gear teeth. The gear pair is required to last for at least 10,000 hrs.
Design the gear drive for the following gear materials: Pinion: Heat
treated Cast Steel, Wheel: High grade cast iron.
(C)
10.Design a pair of helical gears to transmit 5kW at 1500 r.p.m. The
transmission ratio is to be 3 and the helix angle is 150. Assume all data.(C)

UNIT III

21. Define bevel gear.(R)

The gears are formed by cutting teeth along the elements of frustum of cone is
called bevel gear
22. Differentiate straight bevel gear and spiral bevel gear.(AN)
Straight bevel gears:
If the teeth on the bevel gear are parallel to the lines generating the pitch cones
are called as straight bevel gears
Spiral bevel gears:
When the teeth of a bevel gear are inclined at an angle to the face of the bevel is
called as Spiral bevel gears

23. What are the classifications of bevel gear based on teeth shape?(U)
a) Straight bevel gear
b) Spiral bevel gear
c) Zerol bevel gear
d) Hypoid gear

24. Define Crown gear.(R)

When the bevel gears connects two shafts whose axes intersect at an angle
greater than a right angle and one of the bevel gears has a pitch of 90 then it is known
as a crown gear.

25. Formulate equation for transverse module for bevel gears.(C)

26. Formulate the equation for cone distance for bevel gears.(C)

27. Calculate the pitch angle for pinion and wheel if the transmission ratio is 1.6 (C)
28. Calculate the pitch diameter of pinion and wheel if the transverse module is 5mm
and the number of teeth of pinion and wheel is 20 and 48. (C)

29. Formulate the equation of tip diameter for the pinion and wheels for bevel
gears.(C)

30. Formulate the equation for design contact stress for bevel gears.(C)
31. Examine are the advantages of worm gear drive? (AN)
a) Steep ratios as high as 300:1
b) Operation is smooth and silent
c) Worm gear drives are irreversible
32. How do you Calcify the specification of a pair of worm gears? (U)

33. A pair of worm gear is designated as 2/54/10/5. Calculate the center distance. (C)

34. Formulate the equation for calculating the efficiency of the worm gear drive.(C)

35. Formulate the equation for induced bending stress for worm wheel.(C)

36. Write the formula for calculate the length of the worm gear if the number of starts
is 3 and 4? (C)

37. Define lead angle (R)

Lead angle:
It is the angle between the tangent to the pitch helix and the plane of rotation
38. Define velocity ratio or Gear ratio. (R)
It is defined as number of teeth on worm gear to the number of teeth on worm. It
is denoted as i
39. schedule the various losses in the worm gear? (A)
a) Losses due to friction in sliding
b) Losses due to splashing of lubricating oil

40. In worm gear drive, only the wheel is designed. Why? (C)
Since always the strength of the worm is greater than worm wheel, therefore only
the worm wheel is designed.

PART B
1. Design a pair of bevel gear for two shafts whose axes are at right angles. The
power transmitted is 25kW. The speed of pinion is 500r.p.m and the wheel gear is
200r.p.m.
(C)
2. A 900 straight bevel gear set is needed to give 3:1 reduction if the speed of the
pinion is 1440 r.p.m has to transmit 15kW power. A 200 pressure angle involutes
tooth gear pinion is used. The pinion has 25 teeth. Design a suitable gear derive
(C)
3. Design a bevel gear drive to transmit 10kW at 1500r.p.m. Gear ratio is 3, material
for pinion and gear is C45 Steel with surface hardness is < 350 HB and gear life is
10,000 hrs (C)
4. Design a bevel gear drive to transmit 4kW at 225r.p.m. Speed ratio is 4, gear life is
26,000 hrs (C)
5. Write the design procedure for the worm gear (C)
6. Design a worm gear drive to transmit 18 kW at a worm speed of 1440r.p.m. The
speed ratio is 24. The minimum required efficiency of the drive is 85%. Check the
design for heat dissipation and give your inference.
(C)
7. Design a worm gear drive to transmit 22.5 kW at a worm speed of 1440r.p.m. The
speed ratio is 20. The minimum required efficiency of the drive is75%. The
temperature rise should be restricted to 400 C (C)
8. Design a worm gear drive to transmit 12kW at a worm speed of 1440r.p.m. The
speed ratio is 20. The minimum required efficiency of the drive is75%. The
temperature rise should be restricted to 400 C and calculate the required cooling
area (C)
9. Design a worm gear drive to transmit 7.5kW from a worm rotating at 1440r.p.m to a
worm wheel at 20r.p.m (C)
10. Speed reducers wait to be designed for an input of 11.25 kW with a transmission
ratio of 20. The speed of the hardened steel worm is 1500r.p.m. The worm wheel is
to be made of bronze. The tooth form is to be 200 involutes.
(C)
11. Design a worm gear drive to transmit 3kW at 600r.p.m Speed of the worm wheel is
40r.p.m. Assume the efficiency is 78% and tabulate the results.
(C)

UNIT IV
1. What are the principles to be Examine to obtain optimum design in multi speed
gear box? (AN)
To avoid excessively large diameter of the wheel and also to limit the pitch line
velocity of the gear the following principles are considered.
a) Number of gears on the last shaft (spindle) should be minimum.
b) Number of gears on the shaft should not be more than 3, though in exceptional it
may be 4.
c) It is preferable to have n max > n input > n min. In all stages except in the first stage.

2. Define Step ratio? (R)

The ratio between the adjacent speeds in a multi speed gear box is called Step
ratio or Series ratio or Progression ratio. It is denoted by Ф
3. Find the progression ratio of 12 speed gear box having speeds between 100 and
300rpm? (N)

4. List six standard speeds starting from 18 rpm with a step ratio 1.4. (R)

5. Sketch the kinematics layout of gears for 6 speeds between two shafts. (A)

6. What is preferred structural formula? (C)

7. Define is speed reducer? (R)

If a gear box is used to reduce the input speed, then it is called speed reducer

8. What is the use of gear box in a machine tool? (A)

a) Required torque and speed.
b) Change in the direction of rotation.
c) Multispeed in more number of steps.

9. Sketch the ray diagram for a six speed gear box. ( A)

10. Give some Use of speed reducers. (A)

Speed reducers are used in turbine generators, rolling mills, cement factories,
paper plants, and chemical industries

11. What is a structural diagram. (A)

The structural diagram is a graphical representation of structural formula. The
structural formula gives a particular arrangement of get the required output speed.

12. What is the information’s needed for the structural diagram? (A)
a) Number of shafts in a gear box
b) Number of gears in shaft
c) Order of changing transmission in individual groups to get the desired speed
d) Transmission range

13. What is ray diagram? (A)

Ray diagram is a graphical representation of speed ratios between adjacent
shafts from input shaft to output shaft. It is also called as speed diagram
14. Select the speed if the maximum and minimum speeds are 50 rpm and 500 rpm
and the number of speeds is 12. (E)

15. Analyze the possible arrangements to achieve 12 speeds from a gear box? (A)
The possible arrangements to achieve 12 speeds from a gear box are,
2x2x3, 2x3x2, 3x2x2.

16. What is the information’s needed for the ray diagram? (A)
a) Number of stages.
b) Number of speed sin each stage.
c) The Order of kinematic arrangement of the stages.
d) Total number of speed available at the spindle.

17. Relate the basic rules for optimum gear box design? (AN)
a) Transmission ratio (i) in a gear box is limited as
b) The speed ratio at any stage should not be greater than 8
c) In all stages except first stage, Nmax > N input > Nmini
d) The minimum number of teeth in smaller gear drive should not greater than 17

18. List any two methods used for changing speeds in gear box. (R)
a) Constant mesh gear box
b) Sliding mesh gear box

19. Draw the ray diagram for a 9 speed gear box. (A)

20. Define is a gear box? (R)

A gear box is a device employed for stepped regulation of the input speed and to
give required output speeds. It consists of gears, shafts, levers, keys, etc,
PART B
1. A six speed gear box is required to provide output speeds in the range of 125 to
400 rpm with a step ratio of 1.25 and transmit a power of 5 kW at 710 rpm. Draw
the speed diagram and kinematics diagram. Determine the number of teeth
module and face width of all gears, assuming suitable materials for the gears.
(C)
2. Design a 9 speed gear box for the following data. Minimum speed: 100rpm, step
ratio: 1.25. The input is from a 4KW, 1440rpm motor. Draw the speed diagram,
kinematic diagram and indicate the number of teeth on each gear. (C)
3. Design a nine – speed gear box for a machine to provide speeds ranging from100
to 1500 rpm. The input is from a motor of 5 kW at 1440 rpm. Assume any alloy
steel for the gear.
(C)
4. A machine tool gear box is to have 9 speeds. The gear box is driven by an electric
motor whose shaft rotational speed is 1400 rpm. The gear box is connected to the
motor by a belt drive. The maximum and minimum speeds required at the gear
box output are 1000 rpm and 200 rpm respectively. Suitable speed reduction can
also be provided in the belt drive. What is the step ratio and what are the values of
9 speeds? Sketch the arrangement. Obtain the number of teeth on each gear and
also the actual output speeds.
(C)
5. Select speeds for a 12 speed gear box for a minimum speed of 16 rpm and a
maximum speed of 900rpm. Draw the speed diagram, kinematic diagram and
indicate the number of teeth on each gear. (C)

6. Design the layout of a 12 speed gear box for a milling machine having an output of
speeds ranging from 180 to 2000 rpm. Power is applied to the gear box from a 6
kW induction motor at 1440 rpm. Choose standard step ratio and construct the
speed diagram. Decide upon the various reduction ratios and number of teeth on
each gear wheel sketch the arrangement of the gear box (C)
7. Design the headstock gear box of a lathe having nine spindle speeds ranging from
25 to 1000 rpm. The power of the machine may be taken as 6 kW and speed of the
motor is 1450 rpm. Minimum number of teeth on the gear is to be 25. a) Draw the
speed diagram b) Sketch the layout of the gear box.c) Calculate the number of
teeth on all gears
©
8. A gear box is to be designed for the following specifications:
Power to be transmitted = 5.5KW
 Number of speeds = 9

Minimum speed = 280 rpm

Maximum speed = 1800 rpm

Input motor speed = 1440 rpm

Draw the kinematic layout diagram and the speed diagram. Determine the number
of teeth on all gears. (C)

9. Draw the ray diagram and kinematic lay out of a gear box for an all geared
headstock of a lathe. The maximum and minimum speeds are to be 600 and 23
rpm respectively. The number of steps is 12 and drive is from a 3 kW electric
motor running at 1440rpm
(C)
10. Select speeds for a 12 speeds gear box for a minimum speed of 112 rpm and
maximum speed of 1400 rpm. Drive speed is 1400 rpm. Draw speed diagram and a
kinematic arrangement of the gear box showing the number of teeth in all the
gears. (C)
11. The spindle of a pillar drill is to run at 12 different speeds in the range of 100rpm
and 135 rpm. Design a three stage gear box with a standard step ratio. The gear
box receives 5KW from an electric motor running at 360rpm. Sketch the layout of
the gear box, indicating the number of teeth on each gear. Also sketch the speed
diagram.
(C)

UNIT V

1. Define jerk. (R)

The rate of change of acceleration with respect to time is called jerk.

2. Define clutch. (R)

It is a device to engagement or disengagement the clutch of driving shaft to the driven
shaft according to the requirement.
3. Examine the function of clutch? (AN)
a) Reduce shocks transmitted between machine shafts.
b) Connect and disconnect the shafts.
c) Maintain constant power, torque and speed.
4. Explain the properties considered for the frictional surface material?
(AN)
a) High coefficient of friction.
b) Withstand high temperature during operation
c) High heat conductivity, high resistance to wear.
d) Not affected by moisture or oil.
5. Explain the types of friction clutches? (AN)
a) Disc or Plate Clutch
b) Cone Clutch
c) Centrifugal Clutch
d) Internal expanding rim Clutch
e) External compressing rim Clutch
6. Explain meant by positive clutch? (AN)
A clutch which transmits power from driving shaft to the driven shaft by means of jaws
or teeth is called positive clutch. Jaw clutch are superior to friction clutches in that they
ensure exact contact (without slipping), produce equality in angular velocities of the
connected shafts.

7. Explain Give the essential three elements in internal shoe rim clutch.
(AN)
It consists essentially of three elements.
a) The mating frictional surface
b) The means of transmitting the torque to and from the surface.
c) The actuating mechanism.
8. Define expanding ring clutch. (R)
The expanding ring clutch is often used in textile machinery, escalators, and machine
tools where the clutch may be located within the driving pulley. Expanding ring clutches
benefit from centrifugal effects. Transmit high torque, even at low speed, and require
both positive engagements and sample release force.

9. Explain the different characteristics of clutch? (AN)

The different characteristics of clutch are,
a) They do not slip
 b) No heat is generated
c) They cannot be engaged at high speeds
d) Sometimes they cannot be engaged when both shafts are at rest.
e) Engagement at any speed is accompanied by shock.
10.Distinguish between Wet and Dry operation of clutches? (AN)
Dry Clutch:
Friction and torque capacity are high, but heat dissipation is more difficult.
Wet clutch:

To dissipate the heat, a lubricant is provided. This reduces the  and the torque
carrying capacity.

11.Define cone clutches. (R)

A cone clutch consists of inner and outer conical working surfaces. The outer
cone is keyed to the driving shaft, while the inner cone is free to slide axially on the
driven shaft due to splines.

12.Define brakes. (R)

A brake defined as a mechanical device which is used to absorb the energy
possessed by a moving system or mechanism by means of friction. The primary purpose
of the brake is to slow down or completely stop the motion of a moving system, such as
a rotating drum, machine or vehicle.

13.Explain the types of brakes? (AN)

a) Block or shoe Brake
 Single block brake
 Pivoted block brake
 Double block brake
b) Band Brake
 Single Band Brake
 Double Band Brake
c) Band and Block Brake
d) Internal expanding shoe Brake
e) External compressing shoe Brake
14.Explain THE self-energizing brake? (AN)
When the moment of applied force (F. l) and the moment of the frictional force ( . RN .
C) Are in the same direction, the frictional force helps in applying the brake. This type of
brake is known as a self- energizing brake.
 15.Name four materials used for lining of friction surfaces in clutches. (A)
a) Organic materials like leather, wood, cork or felt in conjunction with cast
iron, steel or brass
b) Metals like nodular iron, stainless steel, monel metal and Aluminum
c) Materials like asbestos, moulded or woven with metal chips of brass or
copper
16.List out five important characteristics of the brake lining. (R)
If should have high coefficient friction, low wear rate, high heat resistance, high heat
dissipation capacity and adequate mechanical strength.

17.What are materials used for brake lining? (A)

a) Cast iron on Cast iron
b) Bronze on cast iron
c) Steel on Cast iron
d) Wood on Cast iron.
18.Define braking torque. (R)
The braking torque depends upon the amount of energy absorbed by the brake. That
is a mechanical system of mass m moving with a velocity v1 is allowed down to velocity
v2 during the period of braking.

19.Define internal expanding brake. (R)

It consists of a shoe which is pivoted at one end and subjected to an acting
force p at the other end. A friction lining is fixed on the shoe and the complete
assembly of shoe lining and pivot is placed inside the brake drum.

20.Define What is fade? (R)

The co-efficient of friction gradually rises, reaches a peak value and falls
rapidly as drum temperature is increased. This rapid fall is known as fade.

PART B

1. A single plate sketch, effective on both sides, is required to transmit 25

KW at3000 rpm. Determine the outer and inner diameter of frictional
surfaces if the coefficient of friction is 0.25, ratio of diameter is 1.25 and
the maximum pressure is not to exceed 0.1 N/mm2. Determine (i) the
 face width required and (ii) the axial spring force necessary to engage the
clutch. (C)
2. A dry single plate clutch is to be designed for an automotive vehicle
whose engine is rated to give 100KW at 2400 rpm and maximum torque
500 N-m. The outer radius of the friction plate is 25% more than the inner
radius. The intensity of pressure between the plates is not to exceed 0.07
N/mm2. The coefficient of friction may be assumed to be equal to 0.3.
The helical springs are required by this clutch to provide axial force
necessary to engage the clutch are 8. If each spring has a stiffness of
40N/mm. Determine the dimensions of the friction plate and initial
compression in the springs.
(C)
3. A plate clutch with maximum diameter 60mm has maximum lining
pressure of 0.35 MPa. The power to be transmitted at 400 rpm is 135 KW
and µ= 0.3. Find inside diameter and spring force required to engage the
clutch. Springs with spring index 6 and material spring steel with safe
shear stress 600 MPa are used. Find the diameters if 6 spring are used.
(C)

4. A multi disk clutch consists of five steel plates and four bronze plates. The
inner and outer diameters of friction disks are 75mm and 150mm
respectively. The coefficient of friction is 0.1 and the intensity of pressure
is limited to 0.3. N/mm2.Assuming the uniform wear theory, calculates (i)
the required operating force, and (ii) power transmitting capacity at 750
rpm. (C)
5. A multi disc wet clutch is to be designed for a machine tool driven by an
electric motor of 12.5 KW running at 1440 rpm. Space restrictions limit
the outside disc diameter to 100mm. Determine the appropriate value of
 inside diameter, total number of discs and clamping force.
(C)
6. A hydraulically operated clutch is to be designed for an automatic lathe.D
etermine the number of plates and operating force required for the clutch
to transmit 35 Nm. The clutch is to be designed to slip under 300% of
rated torsional moment to protect the gears and other part of the drive.
The limits for the diameter of friction surfaces due to space limitation are
100mm and 62.5mm. This clutch is to operate in an oily atmosphere.
(C)
7. An engine developing 45kW at 1000 rpm id fitted with a cone clutch built
inside the fly wheel. The cone has a face angle of 12.5 degree and a
maximum mean diameter of 500 mm. The coefficient of friction is 0.2. The
normal pressure on the clutch face is not exceeded 0.1N/mm2. Determine
(i) The face width required (ii) the axial spring force necessary to engage
the clutch. (C)
8. A leather faced conical clutch has cone angle of 30 degree. The pressure
between the contact surfaces is limited to 0.35N/mm2 and breadth of the
conical surface is not to exceed 1/3 of the mean radius. Find the
dimensions of the contact surfaces to transmit 22KW at 2000rpm. Also
calculate the force required to engage the clutch. Take coefficient of
friction as 0.15. (C)
9. Calculate the average bearing pressure and the initial and average braking
powers for the block shoe shown in fig.B1. The diameter of the drum is
400 mm and it rotates at 200 rpm. Coefficient of friction is 0.2 and drum
width is 75 mm. (C)