Deck 3: Mechanical Engineering: Balancing, Cam Profiles, Dynamometers, Pulleys, Gears

Question 1

In order to balance the reciprocating masses, the conditions to be satisfied are

A)Primary forces must balance
B)All above conditions must be satisfied
C)Secondary couples must balance
D)Primary couples must balance
E)Secondary forces must balance

Answer 1

All above conditions must be satisfied

Question 2

A cam profile is the

A)Actual working contour of the cam
B)Profile of path traced by a cam follower
C)Total surface area of the cam
D)Path which the cam follower traces
E)The profile of the path to be traced by the mechanism driven by follower

Answer 2

Actual working contour of the cam

Question 3

The number of instantaneous centres for a four bar chain mechanism would be

A)4
B)6
C)5
D)3
E)2

Answer 3

6

Question 4

Which dynamometer will be most suitable for measuring the BHP of an automobile engine?

A)Electrical generator type
B)Rope brake type
C)Prony brake
D)Electrical resistance type
E)Hydraulic

Question 5

In case of locomotives, the effect of hammer blow is counteracted by

A)Flanges of the tyres of the wheels
B)Balancing weights
C)Inside section of the rails
D)Dead weight of the engine
E)All of the above

Question 6

A 0.5 kg weight attached to a light spring elogates it 7.87 mm. The natural frequency of the system would be in the range

A)100-175 cpm
B)300-350 cpm
C)175-290 cpm
D)25-50 cpm
E)50-100 cpm

Question 7

The secondary critical speed of a shaft occurs at

A)Twice the primary critical speed
B)Occurs only when there are more than 2 rotors on a shaft
C)Four times the primary critical speed
D)If the externam exciting system has a frequency other than the primary critical speed
E)Half the primary critical speed

Question 8

Which of the following instruments may be used in vibration measurements?

A)Photometer
B)Accelerometer
C)Dynamometer
D)Balometer
E)None of the above

Question 9

In locomotives the unbalanced part of the primary disturbing force due to reciprocating masses, cause

A)Variation of tractive effect
B)Periodical vibrations
C)Lifting of locomotive
D)Oscillation in vertical planes
E)Hammer blow

Question 10

The 'crowning' of flat pulleys is generally done pulley

A)To reduce belt friction
B)To prevent belt joining from damaging the belt surface
C)To prevent the belt from running off the pulley
D)In case of cross belt drives only
E)None of the above

Question 11

V belt having cross-section A is suitable for usual load of 5 HP. If 15 HP load is to be transmitted

A)Toothed belts may be used
B)3 Vee belts using 3 groove pulley may be used
C)Machine arrangement may be modified
D)Drive system may be changed
E)Gear system may be adopted

Question 12

The efficiency in case of worm gear drives is generally in the range

A)70-85 percent
B)50-70 percent
C)10-25 percent
D)25-40 percent
E)40 - 60 percent

Question 13

Two shafts have their axes not in the same straight line. Also their axes are not parallel but intersecting. Which of the following coupling can be used for these shafts?

A)Flexible coupling
B)Universal coupling
C)Oldham's coupling
D)Rigid coupling
E)Any of the above

Question 14

Coriolis component is not involved in

A)Andreau variable stroke engine mechanism
B)Slider crank mechanism
C)Line sliding in a swivelling pin
D)Quick return mechanism
E)Tangent cam acceleration

Question 15

Idler pulley is used for

A)Maintaining belt tension
B)Changing direction of rotation
C)For stopping motion frequently
D)For running during idling periods only
E)None of the above

Question 16

Contact ratio of gear should be

A)One
B)More than one
C)Less than one
D)Not defined
E)None of the above

Question 17

The number of nodes in a shaft carrying three rotors will be

A)Three
B)Zero
C)Four
D)Two
E)One

Question 18

By using large thread angles in a lifting machine

A)The mechanical advantage will be low
B)The mechanical advantage will be high
C)The load will be sustained in absence of effort
D)The load will be easily lifted
E)While unloading, little effort will be required

Question 19

The throw of a cam is the maximum distance of the follower from

A)Starting to finish
B)Inner most circle
C)Root circle
D)Pitch circle
E)Base circle

Question 20

The number of degrees of feeedom for a vibrating beam will be

A)Nil
B)Four
C)Two
D)Five
E)One

Question 21

Which of the following is a lower pair?

A)Piston and cylinder
B)Cam and follower
C)Belt drive
D)Gear
E)None of the above

Question 22

Which of the following is a dead weight governor?

A)Porter governer
B)Hartness governer
C)Watt governor
D)None of the above
E)None of the above.

Question 23

The mechanism used in a petrol engine is

A)Crank mechanism
B)Slider mechanism
C)Slider crank mechanism
D)Natural line and circular mechanism
E)None of the above

Question 24

In the Crossby engine indicator which one of the following mechanism is used?

A)Slider-crank mechanism
B)Scotch yoke mechanism
C)Scotch yoke mechanism.
D)Modified pantograph mechanism
E)None of the above

Question 25

Timing belt

A)Have no slip
B)Have maximum slip during starting
C)Slip in proportion to the time of operation
D)Are used to determine the life time of a belt
E)None of the above