Mechanical Engineering Interview Questions

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Answered by: bala

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Member Since Nov-2005 | Answered On : Aug 2nd, 2008

Thare are 4 types of gear box.
1. sliding mesh gear box.
2.constant mesh gear box.
3.synchromesh gear box.
4.planetarty gear box.

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Answered by: padmaja

although four stroke engine is more frequently used 2STROKE engine is more effiecient because for every 2 strokes there is a power stroke.for same power generation 2STROKE ENGINE is compact

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Answered by: Stercus

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Member Since Dec-2007 | Answered On : Aug 17th, 2009

Akash, your FBD won’t work if you leave off external contacts – they need to be converted to force arrows. The buoyed object provides one such force: the buoyant reaction force.

You seem to agree that there is a force acting upwards on the test tube, appearing on the spring balance acting against the weight. As the test tube and the bowl of water are stationary, not accelerating, there must be an equivalent reaction force acting downwards on the body of water, imparted by the object. To go into more detail, the surface of the object experiences a pressure distribution from the water, gradated downwards due to increasing pressure within the water body. The net result from the pressure distribution is that the water pushes up on the object (buoyant force). To avoid being crushed, the object pushes back against this pressure in all directions – so again you get net a reaction force in the opposite direction, downwards.

So the FBD of the water body needs a reaction force to account for buoyancy. This reaction force acts downwards, from the centre of the displaced volume and is equal to the weight of the water displaced. The weight of the object immersed doesn’t need to be considered as this is supported but the weight of the displaced volume of water does.

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Answered by: ramanan33

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Member Since Jun-2008 | Answered On : Jun 8th, 2008

parabola

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Answered by: Anne Srinivas.

A 4-s engine is that in which for every four revolutions of crank one power stroke is produced.  

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Answered by: hosam_ozo

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Member Since Apr-2010 | Answered On : Aug 8th, 2010

First thing you have to know is what is called cetane and octane number.

The octane number is the percentage of octane in the mixture of fuel
The centane number is the percentage of cetane
The octane number expresses the self ignition temperature, as this no. increases the self ignition temperature increases too and this make the knock to be avoidable and the cetane no. is vice verse

**Octane no. increase self ignition increase and cetane no decrease"" SIE needs high octane no"
**Cetane no increase the octane no decrease and the self ignition temperature decrease" CIE needs this"

Case 1: SI engine we dont want the Self Ignition to be reached we use a fuel have a high octane to avoid the knock "which damage the engine"

Case 2: CI the compression ratio is too high "12:22" and this kind of engine depends essentially on the self ignition temperature so we use a fuel with high cetane no "low octane" as the high cetane "low octane" gives low self ignition temperature and that is we need in the CIE..

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Answered by: santoshmit

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Member Since Dec-2007 | Answered On : Dec 26th, 2007

used to measure  rpm,more importantly  to monitor the condition of a  high speed rotatating m/c

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Answered by: dibugwu ifeanyi

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Member Since Nov-2008 | Answered On : Nov 19th, 2008

Gear drive, Belt drive and Chain drive.

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Answered by: bhargavmech

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Member Since Jul-2009 | Answered On : Aug 1st, 2009

The maximum efficiency of the carnot engine only depends on two factors:

1 - The temperature of the hot reservoir (TH)
2 - The temperature of the cold reservoir (TC)

And is given by (TH - TC) / TH « or » 1 - TC / TH So by that we can see the maximum efficiency (100%) would be when the difference of temperatures between the two reservoirs is infinite.

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Answered by: richa tiwari

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Member Since Aug-2009 | Answered On : Aug 30th, 2009

When petrol is used in diesel engine, the engine will not work as gasoline (petrol) has high ignition temperature and therefore has to be ignited by spark-ignition. Diesel engine on the other hand works on the principal of self-ignition in compressed fuel which is not possible with petrol.

When diesel is used in petrol engine, there will be sudden combustion in the fuel due to spark ignition  bcoz diesel has low ignition temperature. This will lead to high knocking, which is absolutely undesirable.

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Answered by: bhargavmech

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Member Since Jul-2009 | Answered On : Aug 5th, 2009

When Tyres are parked for extended periods, tires dry out, discolor and eventually crack and split. The major factor degrading tires and other synthetic and rubber products is ozone, an odorless gas which is part of the air we breath. When combined with ultraviolet light (the invisible part of sunlight) a reaction occurs that attacks the tire polymer. To protect against ozone and UV damage, a stabilizer molecule called a “competitive absorber” is blended with the tire polymer. Competitive absorbers work by capturing and absorbing UV radiation and converting it to heat which is dissipated harmlessly. All tire manufacturers use the same competitive absorber, carbon black. This is why all tires are black

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Answered by: bhargavmech

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Member Since Jul-2009 | Answered On : Jul 30th, 2009

DTS-Fi stands for "Digital Twin Spark Fuel Injection", a ‘Bajaj Patented Technology’. In fuel injection, the conventional carburettor has been replaced by injector which injects fuel in to the engine in a spray form based on the instructions of the Engine Control Unit (ECU) which is a part of the Engine Management System EMS. The Electronic Control Unit (ECU) is microprocessor based and is the brain of the fuel injection system. It processes information sent by various sensors and instantly determines optimum fuelling and spark timing for various engine-operating conditions. The ECU contains detailed information of the engine's characteristics from which it picks the necessary data for commanding both fuelling & spark timing.

The main advantages of Fuel Injection are: a. Increased power output for same cc. b. Better low-end torque. c. Lower fuel delivery & optimisation of spark timing. d. Improved cold start, quick warm-up and excellent response to sudden acceleration. e. Lower emission levels. f. Self-detection and communication of fuel system malfunctioning if any.