Bevel Gears - 2k9 MED University of Engineering & Technology Taxila

psithurismaccountantUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

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1)

A…………. is used

when large forces act along the screw axis in one direction only:

a)

Square thread

b)

Buttress thread

c)

V thread

d)

acme thread

2)

The efficiency of a square thread screw increases rapidly upto helix angle of:

a)

20

b)

45

c)

90

d)

15

3)

Bearing pressure in power screw

is:

a)

w/
π
.d.t

b)

w/d.t

c)

w/
π
.d.t.n

d)

w/
π
.d^2.t.n

4)

The screw is said to be overhauling if efficiency is……………….. 50%:



a)

More

b)

Less

c)

Equal

d)

None

5)

Screws used for power transmission should have:

a)

Low efficiency

b)

High efficiency

c)

Very fine threads

d)

Strong teeth


1)

Which type of

springs are mostly used in automobiles:

a)

Torsion spring

b)

Disc spring

c)

Leaf spring

d)

Helical spring

2)

When the compression spring is compressed until the coil comes in contact with each
other then the spring is said to be:

a)

Solid length

b)

Free length

c)

Total length

d)

Co
mpressible length

3)

Which spring is widely used for transmitting small torques as in door hinges ,brush
holder in electric motors:

a)

Helical torsion spring

b)

Disc spring

c)

Flat spiral spring

d)

Leaf spring

4)

Stress in the full length leaves is……… 50% than the stress in

the graduated leaves:

a)

Greater

b)

Less

c)

Equal

d)

None

5)

Deflection of helical springs of circular wire is:

a)

8W.C^3.n/G.D^4

b)

8C^3.n/ G.D^4

c)

8W.C^3/ G.D^4

d)

8W.C^3.n/ D^4

e)


1)

The…………….are those which can support steady loads without any relative motion b/w
journal &
bearing:

a)

Thin film bearing

b)

Thick film bearing

c)

Zero film bearing

d)

Externally pressurized lubricated bearing

2)

It is the ability of bearing material to accommodate small particles of dust ,grit without
scoring the material of journal:

a)

Bondability

b)

Embeddability

c)

Comformability

d)

Corrosion resistance

3)

The …………. are used with water or other low viscosity lubricants particularly where
sand or other large particles are present:

a)

Carbon_graphite bearing

b)

Wood bearing

c)

Soft rubber bearing

d)

None of them

4)

It is the lowest temperature at which an oil gives off sufficient vapour to support a
momentary flash actually setting fire to the oilwhen a flame is brought within 6mm at
the surface of oil:

a)

Viscosity index

b)

Flash point

c)

Fire point

d)

Freezing point

5)

A …………….

Is used to guide the shaft which is subjected to a load along the axis of the
shaft:

a.

Thrust bearing

b.

Footstep bearing

c.

Collar bearing

d.

Bushed bearing


1)

In helical gears the distance b/w similar faces of adjacent teeth along a helix on the pitch
cylinders n
ormal to teeth is called:

a)

Normal pitch

b)

Axial pitch

c)

Diametral pitch

d)

Module

2)

End thrust given by in helical gears is:

a)

W tan
α

b)

W cos
α

c)

W sin
α

d)

None

3)

The helix angle for double helical gears may be made upto:

a)

45

b)

60

c)

70

d)

90

4)

The thickness of rim for the gear is

a)

m




b)

t





c)

m







d)

m





5)

The helix angle for single helical gear ranges from

a)

10____15

b)

15____20

c)



20____35

d)

35____50






1)

The bevel gears are used for transmitting power at a………… velocity ratio b/w two
shafts whose axis intersect at a certain angle:

a)

Uniform

b)

Variable

c)

Fluctuating

d)

Constant

2)

When the teeth on the bevel gear are cut on the inside of the pitch cone then they
are known as:

a)

Crown bevel gear

b)

Mitre gear

c)

Internal bevel gear

d)

Angular bevel gear

3)

The………… angle is equal to the pitch angle plus addendum angle

a)

Root angle

b)

Face angle

c)

Dedendum angle

d)

Helix angle

4)

Dedendum cone diameter is given by:

a)

D

+2
α
cos
Ɵ
p

b)

D

-
2
d
cos
Ɵ
p

c)

D

+2
d
cos
Ɵ
p

d)

D

-
2
α
cos
Ɵ
p

5)

For a bevel gear having the pitch angle the ratio of formative no. of teeth to actual
no. of teeth:

a)

1/sinƟ

b)

1/cosƟ

c)

1/tanƟ

d)

sinƟ cosƟ


1)

The worm gear are widely used for transmitting power at……. Velocity ratios b/w non
intersecting shafts that are not generally but not necessary at right angle:

a)

Low Velocity

b)

High Velocity

c)

Average Velocity

d)

Medium Velocity

2)

The………… is also used for
light service:

a)

Hobbed straight face worm gear

b)

straight face worm gear

c)

Concave face worm gear

d)

Convex face worm gear


3)

The………. Angle b/w the tangent to the thread helix on the pitch cylinder and the axis of
the worm:

a)

Helix angle

b)

Lead angle

c)

Tooth pressure ang
le

d)

Pitch angle

4)

The no. of starts on the worm for a velocity ratio of 40 should be:

a)

Single

b)

Double

c)

Triple

d)

Quadruple

5)

In designing a worm and worm gear which quantity is not given:

a)

Speed

b)

Velocity

c)

Power transmitted

d)

Lead angle


1
-
The power screws with multiple
threads are usually found in:

a)

High speed cars

b)

High speed tools

c)

High speed actuators

d)

High speed steel

2
-
The efficiency of square threaded screws may be defined as the ratio between the ideal
---------------
to
the actual effort:

a)

Effort

b)

Load

c)

Friction

d)

Mechanica
l advantage

3
-
Torque required to lower the load i.e T= Wtan(fi
-
alpha), if fi <alpha then torque will be:

a)

Positive

b)

Negative

c)

Both

d)

None

4
-
The co
-
efficient of friction depends upon various factors like:

a)

Material of screw

b)

Quality of lubrication

c)

Both

d)

Only a

5
-
The slow movement of the screw may be obtained as
-------------
pitch of threads:

a)

Large

b)

Medium

c)

Small

d)

Exremely small

6
-
In a closed coiled helical spring the helix angle is:

a)

Greater than 10

b)

Just equal to 10

c)

Less than 10

d)

Not defined

7
-
The major stress induced

in bellevile spring is:

a)

Tensile & shear

b)

Bending & torsion

c)

Twist & tear

d)

Tensile & compressive

8
-
Smaller size wires have:

a)

Greater strength

b)

Less ductility

c)

Less strength

d)

‘a’ & ‘b’

9
-
In leaf spring the longest leaf is known as:

a)

Lower leaf

b)

Upper leaf

c)

Both a & b

d)

Master leaf

10
-
Spring index ‘C’ is calculated as:

a)

d/D

b)

d/2D

c)

D/2d

d)

D/d

11
-
In a bush bearing bush can be:

a)

Replaced

b)

Not replaced

c)

Worn out

d)

Both a & c

12
-
The ZN/P factor helps to predict:

a)

Performance of spring

b)

Strength of bearing

c)

Performance of bearing

d)

None of
all

13
-
The unit of absolute viscosity of the lubricant:

a)

Kgm/s

b)

Nm/s

c)

Kg/ms

d)

No units

14
-
In a thrust bearing the load acts:

a)

In any direction

b)

Along the axis of rotation

c)

Perpendicular to axis of rotation

d)

Parallel to axis

15
-
When the angle of contact of bearing
is 120; the bearing is said to be:

a)

Partial journal bearing

b)

Only journal bearing

c)

Full journal bearing

d)

Thrust bearing

16
-
In helical gears, angle ‘fi’ denotes:

a)

Helical angle

b)

Nominal angle

c)

Normal pressure angle

d)

a & b

17
-
The hellix angle for double helical gear
s may made upto:

a)

90

b)

45

c)

75

d)

120

18
-
In helical gears contact between mating teeth is

a)

General

b)

Diagonal

c)

a & b

d)

gradual

19
-
If P= 22 kW, speed of the driver in a pair of helical gears is 1800 rpm; the torque transmitted by the
pinion will be:

a)

126.7 Nm

b)

116.7 Nm

c)

100

Nm

d)

Cannot be calculated

20
-
The distance of the pitch point from the back of the boss, parallel to the pitch point is called:

a)

Cone distance

b)

Backing

c)

Crown height

d)

Cone center

21
-
It is the maximum diameter of the teeth of gear:

a)

Mounting height

b)

Pitch diameter

c)

Addendum cone diameter

d)

Cone center

22
-
The face angle of a bevel gear is equal to:

a)

Pitch angle+Addendum angle

b)

Pitch angle
-
Dedendum angle

c)

Pitch angle+Dedendum angle

d)

Pitch angle
-
Addendum angle

23
-
It is also linear pitch of a worm:

a)

Circular pitch

b)

Radial pitch

c)

Diagonal pitch

d)

Axial pitch

24
-
Maximum shear stress is calculated by the formula
------------------------
.

25
-
In a worm & worm gear worm gear is:

a)

Driving member

b)

Driven member

c)

Both

d)

None of above

26
-
Normal pressure angle for triple & quadruple threads for worm

gear may be:

a)

6

b)

12

c)

14.5

d)

20

27
-
In worm gearing the quantity of heat generated is given by the formula
------------------------
.

28
-
Conical or volute springs are used in:

a)

Telescopy

b)

Taracopy

c)

Endotherapy

d)

Cars

29
-
The major spring stresses in helical springs are
shear stresses due to:

a)

Crushing

b)

Tension

c)

Turning

d)

Twisting

30
--------------------
spring is used in automobiles of semi
-
elliptical shape:

a)

Conical

b)

Coil

c)

Leaf

d)

half


1.

The material of spring should have

a)

High fatigue

b)

Low resilience

c)

High resilience

d)

Both a and c

2.

In
closely coiled helical spring the helix angle is very small, it is usually less than

a)

5

b)

10

c)

15

d)

20

3.

Laminated springs is also known as

a)

Leaf springs

b)

Flat springs

c)

Carriage springs

d)

All

4.

The springs are mostly made from oil tempered carbon steel wires contain carb
on

a)

0.4
-
0.5%

b)

0.5
-
0.6%

c)

0.6
-
0.7%

d)

0.7
-
0.8%

5.

The turn which impart spring action are know as

a)

Inactive

turn

b)

Active turn

c)

Effective turn

d)

None of these




BEARINGS

1.

The lubricant used to separate the journal and bearing is usually a

a)

A
mineral oil refined from petroleum

b)

Vegetable oil

c)

Silicon oil

d)

All

2.

Depending upon the direction of load to be support the bearing under thin group are classified
as

a)

Radial bearing

b)

Thrust bearing

c)

Both

d)

None

3.

In …… bearing load acts perpendicular to the
direction of motion of moving element

a)

Radial bearing

b)

Thrust bearing

c)

Thick film bearing

d)

Thin film bearing

4.

The …… bearings are these in which the working surfaces are completely separated from each
other by the lubricant

a)

Thin film bearing

b)

Thick film bearing

c)

Zero film bearing

d)

None

5.

The ….. bearing are those which operate without any lubricant present

a)

Thick film bearing

b)

Thin film bearing

c)

Zero film bearing

d)

None




WORM GEAR

1.

Worm gear can give velocity ratio as

a)

100:1

b)

200:1

c)

300:1

d)

400:1

2.

Types of worms

a)

Cylindrical worm

b)

Straight worm

c)

Cone or double enveloping worm

d)

All

3.

……is the linear distance through which a point on a thread moves a head in one revolution of
worm

a)

Axial pitch

b)

Lead

c)

Normal pitch

d)

None

4.

The ……. face worm gear is the accepted standard form and

is used for all heavy service

a)

Convex

b)

Round

c)

Flat

d)

Concave

5.

The hobbed straight face worm gear is used for …….. services

a)

Heavy

b)

Medium

c)

Light

d)

All






HELICAL GEAR

1.

A helical gear has teeth in form of

a)

Flat

b)

Round

c)

Helix

d)

All

2.

…… is the distance parallel to axis between similar faces of adjacent teeth

a)

Normal pitch

b)

Pitch

c)

Axial pitch

d)

Longitudinal pitch

3.

In order to remove axial thrust…………helical gear are used

a)

Single

b)

Double

c)

Both

d)

None

4.

In single helical gear the helix

angle ranges from

a)

45
-
60

b)

30
-
45

c)

20
-
35

d)

15
-
30

5.

Helical gears are used for

a)

Smooth drive

b)

High efficiency of transmission

c)

Both a and b

d)

Low efficiency of transmission






BEVEL GEARS

1.

The bevel gears are used for transmitting power at……….between two shafts
whose axes
intersect at a certain angle

a)

Variable velocity

b)

Constant velocity

c)

Both

d)

None

2.

When the bevel gears connect two shafts whose axes intersect at an angle other than a right
angle then they are known as

a)

Mitre gear

b)

Angular bevel gear

c)

Crown bevel gear

d)

In
ternal bevel gear

3.

The bevel gears may have………….teeth

a)

Straight

b)

Flat

c)

Spiral

d)

Both a and c

4.

When the teeth on the bevel gear are cut on inside of pitch cone then they known as

a)

Mitre gear

b)

Angular bevel gear

c)

Crown bevel gear

d)

Internal bevel gear

5.

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

a)

Mitre gear

b)

Angular bevel gear

c)

Crown bevel gear

d)

Internal bevel gear




SCREW

1.

The square thread result in maximum efficiency and …… on nut

a)

Maximum radial or busting pressure

b)

Minimum radial or busting pressure

c)

No radial or busting pressure

d)

None

2.

Maximum efficiency of a square threaded screw is

a)

1
-
sin
ɸ
/1+sin
ɸ

b)

1+sin
ɸ
/1
-
sin
ɸ

c)

1
-
si
n
ɸ
/sin
ɸ
-
1

d)

None

3.

The power screws with multiple threads such as double and triple etc are employed when it is
desired to secure a……….

a)

Low efficiency

b)

High efficiency

c)

Both

d)

None

4.

The power screw are used to convert ………motion into………. Motion

a)

Linear to rotary

b)

Rotary to linear

c)

Translatory to rotary

d)

Rotary to translatory

5.

Acme threads are also known as

a)

Buttress thread

b)

Trapezoidal thread

c)

Square thread

Worm Gear

Types of worm gear are

a)

2

b)

3

c)

None

……..is mostly as a speed reducers

a)

Worm gearing

b)

Spur gear

c)

None

If
the efficiency of worm gear is less than 50%, then the worm gearing is said to be

a)

Self
-
locking

b)

Locking

c)

None

The ………. Is used to some extent, but it require extremely accurate alignment

a)

Cone or double enveloping worm

b)

Spur gear

c)

None

The number of starts on
the worm for a velocity ratio of 40 should be

a)

Single

b)

Double

c)

None


Bevel Gear

The……. are used for transmitting power at a constant velocity ratio between two shafts whose
axis intersect at a certain angle.

a)

Bevel Gear

b)

Worm Gear

c)

None

When the teeth on the bev
el gear are cut on the inside of pitch cone, they are known as

a)

Internal bevel gear

b)

Bevel gear

c)

None

The action of …………will be same as that of equivalent spur gear

a)

Bevel gear

b)

Worm gear

c)

None

The factor(L
-
B/L) may be called as

a)

Bevel factor

b)

Worm factor

c)

Both

The face angle of a bevel gear is equal to

a)

Pitch angle +addendum angle

b)

Pitch angle

c)

None


Helical Gear

…………has teeth in form of hekix around the gear

a)

Helical gear

b)

Worm gear

c)

None

Helical gears may be of…..

a)

Single helical type

b)

Double helical type

c)

Both

……….is

a constant angle made by helices with the axis of rotation

a)

Helix angle

b)

Axial p itch

c)

Both

Mathematically, formative or equivalent number of teeth on a helical gear

a)

T
e

= T/cos
3
α

b)

T
e

= T/sin
3
α

c)

None

The helix angle for double helical gears may be made up to

a)

45
0

b)

70
0

c)

60
0

Bearing


A ………… is a machine element which support another moving machine element

a)

Bearing

b)

Gear

c)

Cam

…….. the load acts perpendicular to the direction of moving element

a)

Radial bearing

b)

Thrust bearing

c)

Both







Wh
en the angle of contact of the bearing with the journal is 360
0
, then the bearing is called a….

a)

Full journal bearing

b)

Partial journal bearing

c)

None

……the load acts along the axis of rotation

a)

Radial bearing

b)

Thrust bearing

c)

None

………..is used for bearing
subjected to very high pressure

a)

Phosphor bronze

b)

Gun meal

c)

None

Screwed Joints


A …….is formed by cutting a continous helical groove on a cylindrical surface.

a)

Screw thread

b)

Square thread

c)

None

………joints are highly reliable in operation

a)

Screw joints

b)

Riveted jo
int

c)

Welded joint

Root diameter or core diameter is

a)

Major didameter

b)

Minor diameter

c)

None

…….is the surface joining the crest and root

a)

Flank

b)

Root

c)

Crest

…….is half the pitch of the thread

a)

Slope

b)

Crest

c)

Root

Spring

……spring is defined as an elastic body, whose

function is to distort when loaded and to recover
its original shape when the load is removed.

a)

Spring

b)

Shaft

c)

Cam

The …..may be used only application when the load tends to wind up the spring and are used in
various electrical mechanism

a)

Torsion spring

b)

Disc

spring

c)

Helical spring

Light service include springs subjected to loads that are……or very infrequently varied in safety
valve spring.

a)

Static

b)

Dynamic

c)

Rolling

…..spring consist of a number of a flat plates.

a)

Laminated spring

b)

Leaf spring

c)

Both

The turns which impart spring action are known as…..

a)

Active turns

b)

Inactive turns

c)

Both

Springs

1
-

Which of the following spring is used in a mechanical wrist watch?

(a) Helical compr
ession spring (b) Spiral spring
(c)
Torsion spring

(d) Belleville spring


2
-

When a helical compression spring is subjected to an axial compressive
load, the stress
induced in the
wire is

(a) Tensile

stress (b) compressive stress
(c)
shear stress

(d) bending stress


3
-
The sprin
g mostly used in gramophones is

(a) Helical
spring (b) con
ical spring (
c) laminated spring (d
) flat spiral spring


4
-

A leaf spring in automobiles is used

(a) To app
ly forces (b) to measure forces
(c
) to absorb shocks

(d) to store strain energy


5
-

In leaf springs, the longest leaf is known as

(a) L
ower leaf (b)
master leaf

(c) upper leaf (d) none of these


Helical Gears


1
-
Helicalgears may be of or

(a)

Single helical type (b) double helical type (c)
both a & b


2
-

The helix angle for double helical gears may be made up to

(a)

45°

(b)60° (c) 75° (d)90°


3
-

In helical gears, the right hand helices on one gear will mesh

......... helices on the other
gear.

(a)

right hand (b)
left hand

(c)None


4
-

In helical gears, the distance between similar faces of adjacent teeth along

a helix on
the pitch cylinders
normal to t
he teeth, is called

(a)

Normal pitch

(b) axial pitch(c) diametric pitch (d) module



5
-

The helix angle for single helical gears ranges from

(a)

10° to 15° (b) 15° to 20° (c)
20° to 35°

(d) 35° to 50°



Bevel Gears


1
-

If b denotes the face width and L denotes the

cone distance, then the bevel factor is
written as

(a) b / L (b) b / 2L
(c) 1


2 b.L (d)
1


b / L


2
-

The face angle of a bevel gear is equal to

(a)

Pitch angle


addendum angle (b)
pitch angle + addendum angle

(c) pitch angle


dedendum

angle (d) pitch angle + dedendum angle


3
-

The root angle of a bevel gear is equal to

(a)

Pitch angle


addendum angle (b) pitch angle + addendum angle (c)
pitch angle


dedendum angle

(d) pitch angle + dedendum angle


4
-

When bevel gears having equal teeth a
nd equal pitch angles connect
two shafts whose
axes intersect
at right angle, then they are known as

(a)

Angular bevel gears (b) crown bevel gears (c) internal bevel gears (d)
mitre gears


5
-

For a bevel gear having the pitch angle θ, the ratio of formative nu
mber

of teeth (TE)
to actual number
of teeth (T) is

(a)

1/sinθ (b)
1/cosθ

(c) 1/tanθ (d) sin θ cos θ



Worm Gears


1
-

The number of starts on the worm for a velocity ratio of 40 should be

(a)
Single

(b) double
(c) triple (d) quadruple


2
-

The axial thrust on the worm (WA) is given by

(a)
WA = WT .tan φ (b) WA = WT / tan φ(c) WA = WT . tan λ (d)
WA = WT / tan λ


3
-

The worm gears are widely used for transmitting power at ...........velocity
ratios
between non
-
intersecting
shafts.

(a)
High

(b) low


4
-

In worm gears, the angle between the tangent to the thread helix on t
he pitch cylinder
and the plane
normal to the axis of worm is called

(a)

Pressure angle (b)
lead angle

(c) helix angle (d) friction angle


5
-

The normal lead, in a worm having mu
ltiple start threads, is given by

(a) lN = l / cos λ (b)
lN = l . cos λ

(c) lN = l (d) lN = l tan




Bearings


1
-

The ball bearings are usually made from

(a)

low carbon steel(b) medium carbon steel(c) high speed steel(d)
chrome nickel steel


2
-

The tapered
roller bearings can take

(a) Radial load only (b) axial load only(c)
both radial and axial loads

(d) none


3
-

The piston pi
n bearings in heavy duty diesel
engines are

(a)
Needle roller bearings

(b) tapered roller bearings (c) spherical roller bearings

(d)
Cylindrical roller bearings


4
-

Which of the following is antifriction bearing?

(a)

journal bearing (b) pedestal bearing (c) collar bearing (d)
needle bearing


5
-

Ball and roller bearings in comparison to sliding bearings have

(a) More accuracy in alignme
nt (b) small overall dimensions
(c) low starting and running
friction (d)
all of these





Screwed Joints


1
-

A locking device in which the bottom cylindrical portion is recessed to

receive the tip
of the locking
set screw, is called

(a)

castle nut (b) jam nut (c)
ring nut

(d) screw nut


2
-

Which one is not a positive locking device?

(
a)
Spring washer

(b) Cotter pin (c) Tongued washer (d)
Spring wire lock


3
-

The washer is generally specified by its

(a) Outer

diameter (b)
hole diameter

(c)

thickness (d) mean diameter


4
-

A locking device extensively used in automobile industry is a

(a)

jam nut (b)
castle nut

(c) screw nut (d)
ring nut


5
-
The railway carriage coupling have

(a)

square threads (b) acme threads (c) knuckle threads (d)
buttress threads



Power Screws


1
-

A screw jack has square threads and the lead angle of the thread is α. The screw jack
will be self
-
locking when the coefficient of friction (µ) is

(a)

µ > tan α

(b) µ = sin α (c) µ = cot α (d) µ = cosec α


2
-

To ensure self
-
locking in a screw
jack, it is essential that the helix angle is

(a)

larger than friction angle (b)
smaller than friction angle

(c) equal to friction angle
(d) such as to give maximum efficiency in lifting


3
-

A screw is said to be self
-
locking screw, if its efficiency is

(a)

less
than 50%

(b) more than 50% (c) equal to 50% (d) none of these



4
-

A screw is said to be over hauling screw, if its efficiency is

(a) Less than 50% (b)
more than 50%(
c) equal to 50% (d) none of these

5
-

While designing a screw in a screw jack against buckl
ing failure, the end conditions
for the screw are taken as

(a)

Both ends fixed (b) both ends hinged (c) one end fixed and other end hinged (d)
one
end fixed and other end free.




NOTE (answers of the MCQs are underlined )