ADDENDUM MODIFICATION COEFFICIENT 4. CIRCULAR PITCH OF THESE CORREC...

3. Addendum modification coefficient 4. Circular pitch

Of these correct statements are

(a) 1 and 3

(b) 2 and 4

(c) 1, 2 and 3

(d) 1 and 4

IES-59Ans. (c)

IES-60. Assertion

(A): If the helix angle of a helical gear is increased, the load carrying

capacity of the tooth increases.

[IES-1996]

Reason

(R): The form factor of a helical gear increases with the increasing in the

helix angle.

(a) Both A and R are individually true and R is the correct explanation of A

(b) Both A and R are individually true but R is not the correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

IES-61Ans. (a)

IES-62. Match List I with List II and select the correct answer using the codes

given below the Lists:

List I

List II

[IES-2000]

A. Unwin's formula

1. Bearings

B. Wahl factor

2. Rivets

C. Reynolds’s equation

3. Gears

D. Lewis form factor

4. Springs

Code: A B C D A B C D

(a)

1

4

2

3

(b)

2

3

1

4

(c)

1

3

2

4

(d)

2

4

1

3

IES-62Ans. (d)

IES-62. A spur gear transmits 10 kW at a pitch line velocity of 10 m/s; driving gear

has a diameter of 1.0 m. Find the tangential force between the driver and

the follower, and the transmitted torque respectively.

[IES-2009]

(a) 1 kN and 0.5 kN-m

(b) 10 kN and 5 kN-m

(c) 0.5 kN and 0.25 kN-m

(d) 1 kN and 1 kN-m

IES-62Ans. (a)

Power transmitted = Force × Velocity

3

10 10

Force 10

⇒

×

=

×

⇒

=

×

=

10 10

Force

1000 N / m

10

diameter

=

×

Torque Transmitted

Force

2

1000

1

1000 0.5

=

× =

×

=

−

=

−

500N m

0.5 kN m

Wear Strength of Gear Tooth

IES-63. The limiting wear load of spur gear is proportional to (where E

p

= Young's

modulus of pinion material; E

g

= Young's modulus of gear material)

[IES-1997]

Design of Power Transmission System

S K Mondal’s

Chapter 3

E

E

E

E

−

⎛

+

⎞

⎛

⎞

⎛

⎞

( )

^a

(

_p

_g

)

¹

b

^{( )}

^p

^g

c 1

^{( )}

^p

d 1

^{( )}

^g

+

⎜

⎜

⎝

⎟

⎟

⎠

⎜

⎜

⎝

+

⎟

⎟

⎠

⎜

⎜

⎝

+

⎟

⎟

⎠

E

E

E E

E

E

p

g

g

p

IES-63Ans. (b)

Gear Lubrication

IES-64. Match List I (Types of gear failure) with List II (Reasons) and select the

correct answer using the codes given below the Lists

[IES-2004]

List

I

List

II

A. Scoring

1. Oil film breakage

B. Pitting

2. Yielding of surface under heavy loads

C. Scuffing

3. Cyclic loads causing high surface stress

D. Plastic flow

4. Insufficient lubrication

A B C D

A B C D

(a) 2

1

3

4

(b)

2

3

4

1

(c) 4

3

1

2

(d)

4

1

3

2

IES-64Ans. (b)

Simple Gear train

IES-65. In a simple gear train, if the number of idler gears is odd, then the

direction or motion of driven gear will

[IES-2001]

(a) Be same as that of the driving gear

(b) Be opposite to that of the driving gear

(c) Depend upon the number of teeth on the driving gear

(d) Depend upon the total number of teeth on all gears of the train

IES-65Ans. (a)

IES-66. The gear train usually employed in clocks is a

[IES-1995]

(a) Reverted gear train

(b) simple gear train

(c) Sun and planet gear

(d) differential gear.

IES-66Ans. (a)

IES-67.

In the figure shown above, if the

speed of the input shaft of the

spur gear train is 2400 rpm and

the speed of the output shaft is

100 rpm, what is the module of

the gear 4?

(a) 1.2

(b) 1.4

(c) 2

(d) 2.5

[IES-2005]

IES-67Ans. (b)

+

=

mT

mT

35

2

1

=

or T

10

N

N

T

N

= −

×

=

1

i

2

3

T

1

N T

T

T

10 10

=

−

= +

×

×

=

×

×

=

N

N

or 100 2400

or T

40

3 3

2

3

4

i

4

T

T

T

60 T

4

1

4

4

′

+

′

=

′

=

=

m T

m T

35 or m

70

1.4

3

4

(

)

+

2

40 10

IES-68 In a machine tool gear box, the smallest and largest spindles are 100 rpm

and 1120 rpm respectively. If there are 8 speeds in all, the fourth speed

will be

[IES-2002]

(a) 400 rpm

(b) 280 rpm

(c) 800 rpm

(d) 535 rpm

IES-68Ans. (b)

IES-69. A fixed gear having 200 teeth is in mesh with another gear having 50 teeth.

The two gears are connected by an arm. The number of turns made by the

smaller gear for one revolution of arm about the centre of the bigger gear

is

[IES-1996]

(a)

2

4

^(b)

³

^(c)

⁴

^(d)

⁵

IES-69Ans. (d) 1 + 200/50 = 1 + 4 = 5

Compound gear train

IES-70

The velocity ratio in the case of the compound train of wheels is equal to

[IES-2000]

No.of teeth on first driver

No.of teeth on last follower

(a)

(b)

No.of teeth on last follower

No.of teeth on first driver

eth on the followers

Productof teeth on the drivers

Productof te

(c)

(d)

Productof teeth on the followers

Productof teeth on the drivers

IES-70Ans. (d)

IES-71. Consider the gear train

shown in the given figure

and table of gears and

their number of teeth.

Gear :A B C D E F

No of teeth:20 50 25 75 26 65

[IES-1999]

Gears BC and DE are moulded on parallel shaft rotating together. If the

speed of A is 975 r.p.m., the speed of F will be

IES-71Ans. (b)

× ×

×

×

T

T

T

N

or N

rpm

=

=

=

=

×

=

Speed ratio

20 25 26

4

4

975

52

F

A

C

E

×

×

× ×

50 75 65

75

75

N

T

T

T

A

B

D

F

IES-72. A compound train consisting of spur,

bevel and spiral gears are shown in the

given figure along with the teeth

numbers marked against the wheels.

Over-all speed ratio of the train is

(a) 8

(b) 2

(c)

1

(d)

1

8

[IES-1996]

IES-72Ans. (a)

Elements of higher pair like follower in cam

is under the action of gravity or spring force .

speed of lost driven or follower

Train value

speed of the first gear

product of no.of teeth no thedrives

product of no.of teeth on thedrives

speed of the first drive

speed of the last driven or follower

IES-73. In the compound gear train shown in

the above figure, gears A and C have

equal numbers of teeth and gears B

and D have equal numbers of teeth.

When A rotates at 800 rpm, D rotates

at 200 rpm. The rotational speed of

compound gears BC would then be

(a) 300 rpm

(b) 400rpm

(c) 500 rpm

(d) 600rpm

[IES 2007]

IES-73Ans. (b) From the figure r

A

+ r

B

= r

C

+r

D

or T

A

+T

B

=T

C

+T

D

and as N

B

+N

C

it must be

T

B

=T

D

&

T

A

=T

C

N

_{or N}

N

₌

Or

B

D

C

=

N

_A

N

_D

=

800

×

200

= 400 rpm

[

∵

N

B

=

N

_c

]

N

A

C

Reverted gear train

IES-74. Consider the following statements in case of reverted gear train:[IES-2002]