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  • Mechanical and Automobile Engineering Interview Questions

    PuneetVerma

    Member

    Updated: Oct 26, 2024
    Views: 1.5K
    Hi..

    In this thread I will be posting some popular Mechanical Interview Question and there answers too..

    Just Click Watch Thread for future updates to this thread.
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  • PuneetVerma

    MemberAug 26, 2012

    What happens if gasoline is used in a
    Diesel engine?Diesel engine will work ?

    No, It will not work,as the Compression ratio of
    Petrol engine is 6 to 10 & that of Diesel engine
    is 15 to 22. Thus on such high compression,
    gasoline gets highly compressed & it may blast.
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  • PuneetVerma

    MemberAug 26, 2012

    Which Mechanism is used in
    Automobile gearing system ?

    Differential mechanism


    Why different types of sound are
    produced in different bikes though
    they say run on SI engine ?

    Engine specifications are different in different
    manufactures like as Bore Diameter(CC),
    Ignition timing.Also the exhaust
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  • PuneetVerma

    MemberAug 26, 2012

    Why entropy decreases with the
    increase in temperature?

    ds=dQ/TEntropy is inversely proportional to
    the temperature so.as temp. increases,entropy
    decreases.
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  • PuneetVerma

    MemberAug 26, 2012

    1 hp how much watt?
    746.2Watt
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  • PuneetVerma

    MemberAug 26, 2012

    How to calculate bearing number to
    diameter of the inner and outer ?

    Divide the shaft diameter size by 5, it will give
    last two digitof the bearing no. and according
    to type of load we have tochose the type
    of bearing and that will give prior no. ofthe
    bearing.
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  • ganesh kalkutaki

    MemberAug 27, 2012

    Amongs these two which have grater elasticity? Steel or rubber. ans- steel. because steel have grater youngs modulus elasticity than rubber. steel- 200GPA rubber-106N/M2
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  • dhamu91

    MemberAug 27, 2012

    what is seeback effect?
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  • PuneetVerma

    MemberAug 28, 2012

    Definition of Octane number & Cetane
    number
    Octane No.- Octane number is defined as the
    percentage, by volume, of iso octane in the
    mixture of iso octane and h-heptane. It is the
    measure of rating of SI engine.
    Cetane No.- Cetane number is defined as
    the percentage, by volume, of n-cetane in
    the mixture of n-cetane and alpha methyl
    naphthalene. It is the measure of rating of CI
    engine.
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  • PuneetVerma

    MemberAug 28, 2012

    Poisons ratio is higher in (rubber/
    steel/wood) ??
    When a material is compressed in one
    direction, it usuallytends to expand in the other
    two directions perpendicular tothe direction
    of compression. This phenomenon is called
    thePoisson effect. Poisson’s ratio is a measure
    of the Poisson effect.
    For rubber = 0.5
    For steel = 0.288
    For wood < 0.2
    Thus Poisson’s ratio is higher in RUBBER.
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  • PuneetVerma

    MemberAug 28, 2012

    The Fatigue life of a part can be improved
    by ?
    Improving the surface finish by Polishing &
    providing residual stress by Shot peening.
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  • zaveri

    MemberAug 28, 2012

    This question was asked to a guy, who specified his area of interest in his C.V as "power plant engineering".

    A wind turbine helps to generate electricity. so does a still ceiling fan rotating due to the passing wind, generate any power. ?

    No it does not, because, the fan motor is a single phase induction motor, and A.C motors , unlike D.C motors cannot be used as alternators.
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  • NAVATHE SACHIN

    MemberAug 30, 2012

    How to know whether the valve is inlet or exhaust by seeing the engine?
    Inlet valve has more diameter than exhaust valve.
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  • NAVATHE SACHIN

    MemberAug 30, 2012

    steam engine is discovered by jameswatt
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  • NAVATHE SACHIN

    MemberAug 30, 2012

    what is the rpm of steam engine?
    200rpm
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  • NAVATHE SACHIN

    MemberAug 30, 2012

    Is cooling is necessary in the engines?
    yes, cooling is necessary in the engines to satisfy the second law of thermodynamics.
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  • NAVATHE SACHIN

    MemberAug 30, 2012

    Is two strokes engines are suitable for S.I engines?
    No,two stroke engines are not suitable for s.i engines, because loss of fuel is more during scavenging process
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  • CE Designer

    MemberAug 30, 2012

    I was asked in my interview a very basic question yet I panicked.
    What are the different classes of metal alloys?
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  • zaveri

    MemberAug 31, 2012

    CE Designer
    I was asked in my interview a very basic question yet I panicked.
    What are the different classes of metal alloys?
    and what is the answer to that (i am panicking too).

    is it ferrous alloys and non-ferrous alloys ?
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  • CE Designer

    MemberSep 3, 2012

    😀 Yes Ferrous ( cast iron---carbon steels---high alloy steel (tool steel & stainless steel)
    and Non Ferrous like Aluminium, Copper, Magnesium, Titanium, Zinc...
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  • PuneetVerma

    MemberSep 3, 2012

    What is the difference between BSP
    thread and BSW thread?
    The British Standard Pipe thread (BSP thread) is
    a family of standard screw thread types that has been
    adopted internationally for interconnecting and sealing
    pipe ends by mating an external (male) with an internal
    (female) thread.

    British Standard Whitworth (BSW) is one of a
    number of imperial unit based screw thread standards
    which use the same bolt heads and nut hexagonal sizes.
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  • PuneetVerma

    MemberSep 3, 2012

    How Cavitation can be eliminated in a
    Pump?
    Cavitation means bubbles are forming in the
    liquid.
    · To avoid Cavitation, we have to increase the
    Pump size to One or Two Inch;
    · To increase the pressure of the Suction Head,
    or
    · Decrease the Pump Speed.
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  • PuneetVerma

    MemberSep 3, 2012

    Which pump is more efficient Centrifugal
    pump or Reciprocating pump?
    Centrifugal pump.
    Because flow rate is higher compared to
    reciprocating pump. Flow is smooth and it
    requires less space to install. Lower initial cost
    and lower maintenance cost.
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  • PuneetVerma

    MemberSep 3, 2012

    Why Centrifugal Pump is not called as a
    Positive Displacement Type of Pump?
    The centrifugal has varying flow depending
    on pressure or head, whereas the Positive
    Displacement pump has more or less constant
    flow regardless of pressure.
    Likewise viscosity is constant for positive
    displacement pump where centrifugal pump
    have up and down value because the higher
    viscosity liquids fill the clearances of the pump
    causing a higher volumetric efficiency. When
    there is a viscosity change in supply there is also
    greater loss in the system. This means change in
    pump flow affected by the pressure change.
    One more example is, positive displacement
    pump has more or less constant efficiency,
    where centrifugal pump has varying efficiency
    rate.
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  • PuneetVerma

    MemberSep 3, 2012

    Why cavitation will occur in Centrifugal
    Pumps and not in Displacement pumps?
    The formation of cavities (or bubbles) is induced
    by flow separation, or non-uniform flow
    velocities, inside a pump casing. In centrifugal
    pumps the eye of the pump impeller is smaller
    than the flow area of pipe. This decrease in flow
    area of pump results in increase in flow rate. So
    pressure drop happened between pump suction
    and the vanes of the impeller. Here air bubbles
    or cavities are formed because of liquid vapour
    due to increase in temperature in impeller.
    This air bubbles are transmitted to pump which
    forms cavitation.
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  • PRASENJIT TOMAR

    MemberSep 13, 2012

    NIce work ...... helpfull stuff... thanx...
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  • serawit

    MemberSep 13, 2012

    How do you get the belt number for standard v belt surrounding two pulleys?
    Answer:
    the circumference of the imaginary belt line surrounding the pulleys in inches is the belt number.
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  • zaveri

    MemberSep 13, 2012

    Itspuneet
    Why cavitation will occur in Centrifugal
    Pumps and not in Displacement pumps?
    The formation of cavities (or bubbles) is induced
    by flow separation, or non-uniform flow
    velocities, inside a pump casing. In centrifugal
    pumps the eye of the pump impeller is smaller
    than the flow area of pipe. This decrease in flow
    area of pump results in increase in flow rate. So
    pressure drop happened between pump suction
    and the vanes of the impeller. Here air bubbles
    or cavities are formed because of liquid vapour
    due to increase in temperature in impeller.
    This air bubbles are transmitted to pump which
    forms cavitation.
    a much simple answer to this is, that centrifugal is a dynamic type of pump.
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  • ankush sharma

    MemberOct 3, 2012

    here i also attached a file related to interview questions for mechanical engineer.
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  • gopi gulivindala

    MemberOct 6, 2012

    dhamu91
    what is seeback effect?
    when two bodies are different temparature i.e. hot&cold.if they are connected by wires(thermo couple) power will genarate.
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  • The myth buster

    MemberOct 22, 2012

    How can this be possible..so are saying that with the increase in temperature, ds becomes negative..but this isn't possible..as for any process to occur, ds shoulb be greater than or equal to zero..so it's not correct to say that entropy decreases with temperature rise..rather in the ds term there is a term for entropy generation..which settle this issue..this term is always positive or zero and keeps the total entropy change >=0.
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  • Sarathkumar Chandrasekaran

    MemberOct 15, 2013

    What is meant by the term "OVERDRIVE" in automobile?
    It is a term describing the process where the drive shaft speed is more than that of engine shaft speed.So attaining our target speed without stressing the engine to run to its peak speed.It also helps in minimizing the wear of engine as we are using it in optimum performance without high fatigue and also increase efficiency as the fuel consumption is decreased.
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  • Ankita Katdare

    AdministratorNov 17, 2015

    Here are some of the frequently asked questions:

    Explain the reason why big tyres are used in rear of vehicles.

    Explain the basic difference between BS2 and BS3 engine.

    What is an injector pressure in heavy vehicles? Why it is used?

    During the drive torque, what will be the weight shift?

    In a tractor, how the hydrostatic propulsion systems work?

    What is the range of engine efficiency in case of two stroke engine?

    What is back compressor in engines?

    What is octane number and cetane number?

    What is the reason for emitting the white exhaust smoke during start of the vehicle? How will you prevent this?
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  • Satyendr yadav

    MemberAug 31, 2017

    PuneetVerma
    Hi..

    In this thread I will be posting some popular Mechanical Interview Question and there answers too..

    Just Click Watch Thread for future updates to this thread.
    My BEL mechanical interview is on 14 September... Can you suggest something for interview.... Thnx in advance
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  • vhes

    MemberSep 21, 2017

    Nice thread:

    Some of good interview Questions are available here on mechanical design 

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  • Tarun pal

    MemberAug 17, 2018

    i think pre combustion ahead 

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  • Abhay Pandey

    MemberDec 3, 2018

    If any one have an idea which types of questions asked in engine maintenance engineer please share questions with answer  ,thanks 

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  • Hassan Ndaliro

    MemberFeb 24, 2019

    I     am much happy with the Interview questions & answers that you have given here.

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