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Monday, 22 September 2014

MECHANICAL ENGINEERING TERMS 2

MECHANICAL ENGINEERING TERMS:-


1.)GEAR – A wheel with teeth that engage or mesh with teeth of another wheel.

2.)GEAR BOX– A unit which has a series of gears and shafts to vary the speed of the gearbox output shaft compared to the engine speed. This in turn increases the torque and thereby improves acceleration of the vehicle.

3.)GEAR RATIO – The ratio of the number of teeth on two gears to mesh with each other.

4.)HANDLING– The ease of maneuvering a vehicle without slipping or skidding.

5.)HYDRAULIC BRAKE – A brake system using hydraulic fluid, piston and cylinders to provide extremely high pressure for brake application.

6.)HYDRAULIC CLUTCH – A clutch that uses hydraulic pressure to actuate the clutch. Used in heavy duty equipment and where the engine is away from the drivers compartment so that it would be difficult to use mechanical linkages.

7.)HYDRAULIC CONTROL VALVES – A system of valves that senses driving conditions and automatically shifts the transmission.

8.)HYPOID GEARS – Drive pinion and ring gears whose shape allows them to mesh off centre.

9.)INDEPENDENT SUSPENSION – A type of suspension system in which each wheel is independently supported by a spring. A suspension that allows up and down movement of one wheel without affecting the opposite wheel.

10.)INNER TUBE (tyre) – The inside rubber tube assembled in the tyre casing, it maintains the air at sufficient pressure to inflate the casing and adequately support the vehicle weight.

11.)FLUID FLY WHEEL– A liquid coupling used to transmit the engine effort (torque) to a clutch and transmission. This coupling is always a major part of the engine flywheel.

12.)FORWARD CONTROL TRUCK– has the engine either in or below the driver’s cabin.

 MECHANICAL ENGINEERING TERMS 1

13.)FORWARD EFFICIENCY – is the ratio of the amount of driver input torque which is available at the wheels to turn the same to the total amount of input torque from the driver at the steering wheel.

14.)FOUR WHEEL DRIVE– Some cross country vehicles (Jeeps) have this arrangement. In this case, the engine power is transmitted to all the four wheels of the vehicle. The main advantage of this arrangement is the entire vehicle weight is available for traction.

15.)FRAME – The assembly of metal structural parts and channel sections that forms the base and supports the engine and body and is supported by the vehicle wheels.

16.)EMERGENCY BRAKE– is the hand brake, operated by a lever, is used when the vehicle is left parked and prevents the vehicle from moving. The hand brake can be applied to stop the vehicle when the service brake fails.

17.)EPICYCLIC GEAR– In the epicyclic gearing, at least one gear not only rotates about its own axis, but also rotates about some other axis.

18.)FADE (brake) – A condition that occurs when there is little braking effect with full brake pedal force.

19.)FINAL DRIVE – The final gear reduction between the engine and the drive wheels.

20.)FIXED CALIPER DISC BRAKES – Disc brakes using a caliper which is fixed in position and cannot move.

MECHANICAL ENGINEERING TERMS 1

MECHANICAL ENGINEERING TERMS:-



1.)DRAGSTER – Car especially built for drag racing.

2.)DRAG WHEEL – Special steering wheel used on some dragsters. Often consists of cross bar spoke and portion of rim on each end.

3.)DRIVE LINE or DRIVE TRAIN – Propeller shaft, universal joints etc. connecting transmission output shaft to axle pinion gear shaft.


4.)DROP CENTRE RIM – Centre section of rim being lower than two outer edges. This allows bead of tyre to be pushed into lower area on one side while the other side is pulled over and off the flange.

5.)DROPPED AXLE – Front axle altered so as to lower the frame of the vehicle. Consists of bending axle downward at outer ends (solid front axle).

6.)DOUBLE LEADING BRAKE – A drumbrake assembly with both front shoes self energized during forward wheel rotation.


7.)DOUBLE REDUCTION AXLE– In the double reduction or tripple reduction type final drive, the required speed reduction is obtained in two or more steps. This enables higher torque to be available at the road wheels. In heavy duty and off highway vehicles, multiple reduction is used. 

8.)DOUBLE TRAILING BRAKE – A drum brake assembly with both shoes self energized during rearward wheel rotation only.

9.)DRAG – To accelerate a vehicle from standing start, over course one fourth mile in length. Also used by some drivers when referring to challenging another driver to an acceleration race.

10.)DRAG LINK – A steel rod connecting pitman arm to one of steering knuckles. On some installations, drag link connects pitman arm to a centre idler arm.

11.)DIFFERENTIAL LOCK– The differential lock grips one or both of the side gears to the differential case. This prevents their rotation on the pins. This enables a larger torque to be transmitted to the gripping wheel than that to the slipping wheel.


12.)DIRECT ACTING SHOCK ABSORBER – Type of shock absorber which shortens or lengthens in action. Also called telescopic shock absorber.

13.)DIRECT DRIVE – Such as high gear when crankshaft and drive shaft revolve at same speed.

14.)DOUBLE LEADING SHOE – A drum brake having two leading shoes and no trailing shoes. Each shoe has its own actuating mechanism and pivot.


15.)DOUBLE PISTON CALIPER – A hydraulic brake caliper with two pistons and provision for applying hydraulic pressure equally to both pistons. The caliper body is fixed solidly.

16.)DASH BOARD – Part of body containing driving and control instruments, switches etc.

17.)DEAD AXLE – Axle that does not rotate or deliver power but merely forms a base upon which wheels may be mounted.

18.)DEDION – Rear axle set up in which driving wheels are attached to the frame by a central pivot. Differential unit is bolted to frame and is connected to the driving wheels by drive axles.


19.)DEPENDENT SUSPENSION – Wheel connected through an axle member so that movement of one wheel moves the other wheel.

20.)DIFFERENTIAL – A mechanism between axles that permit one wheel to turn at a different speed than the other while transmitting power from the drive shaft to the wheel axles, when the vehicle is negotiating a turn.

Wednesday, 17 September 2014

100 MECHANICAL ENGINEERING INTERVIEW QUESTION AND ANSWER

 100 Mechanical Engineering Interview Question and Answers http://upseexam.blogspot.com/

1. What is the difference between scavenging and
supercharging?

Ans: Scavenging is process of flushing out burnt gases
from engine cylinder by introducing fresh air in the
cylinder before exhaust stroke ends. Supercharging is
the process of supplying higher mass of air by
compressing  the  atmospheric  air.

2. What are the names given to constant temperature,
constant pressure, constant volume, constant internal
energy, constant enthalpy, and constant entropy
processes?

2. Ans: Isothermal, isochoric, isobaric, free expression,
throttling  and  adiabatic  processes  respectively.

3. In a Rankine cycle if maximum steam pressure is
increased keeping steam temperature and condenser
pressure same, what will happen to dryness fraction of
steam after expansion ?Ans: It will decrease.

4. Why entropy change for a reversible adiabatic process
is  zero?

Ans: Because there is no heat transfer in this process.

5. What are two essential conditions of perfect gas?
Ans: It satisfies equation of state and its specific heats
are  constant.

6. Enthalpy and entropy are functions of one single
parameter.  Which  is  that?

Ans:  Temperature.

100 Mechanical Engineering Interview Question and Answers http://upseexam.blogspot.com/
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100 Mechanical Engineering Interview Question and Answers http://upseexam.blogspot.com/

7. Why rate of condensation is higher on a polished
surface  compared  to  rusty  surface?

Ans: Polished surface promotes drop wise condensation
and  does  not  wet  the  surface.

8. How much resistance is offered to heat flow by drop
wise  condensation?

Ans:  Nil

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9. What is the relationship between COP of heating and
cooling?

Ans: COP of heating is one (unity) more than COP of
cooling.

10. How much is the work done in isochoric process?

Ans:  Zero.

11. When maximum discharge is obtained in nozzle?
Ans:  At  the  critical  pressure  ratio.

1. Under what condition the work done in reciprocating
compressor  will  be  least?

Ans: It is least when compression process approaches
isothermal. For this purpose, attempts are made to cool
the  air  during  compression.

13. What is the difference between stalling and surging

100 Mechanical Engineering Interview Question and Answers http://upseexam.blogspot.com/
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100 Mechanical Engineering Interview Question and Answers http://upseexam.blogspot.com/

in  rotary  compressions?

Ans: Stalling is a local phenomenon and it occurs when
How breaks away from the blades. Surging causes
complete breakdown of flow and as such it affects the
whole  machine.

14. Why the electric motor of a fan with backward
curved blades is never got overloaded under any
condition?

Ans: The maximum power is consumed at about 70%
of maximum flow in case ‘of fan with backward blades.
For higher flow, power consumption gets lower.

15. Why the work per kg of air flow in axial flow
compressor is less compared to centrifugal compressor
for  same  pressure  ratio?

Ans: Isentropic efficiency of axial flow compressor is
higher.

16. What is the name given to portion of thermal energy
to  be  necessarily  rejected  to  environment?

Ans:  Energy.

17.  What  is  pitting?  How  it  is  caused?

Ans: Non uniform corrosion over the entire metal
surface, but occurring only in small pits is called pitting.
It is caused by lack of uniformity in metal.

18.  What  is  caustic  embrittlement?

Ans: It is the actual physical change in metal that makes
it extremely brittle and filled with minute cracks. It
occurs particularly in the seams of riveted joints and
around  the  rivet  holes.

19. Which impurities form hard scale and which
impurities  soft  scale?

Ans: Sulphates and chlorides of lime and magnesium
form hard scale, and carbonates of lime and magnesium
form  soft  scale.

20. What is the difference between hard water and soft
water?

Ans: Hard water contains excess of scale forming
impurities and soft water contains very little or no scale
forming  substances.

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50 Mechanical Engineering Interview Question and Answer

Mechanical engineering interview question and answer http://upseexam.blogspot.in/

1. What is the difference between Critical Speed and Whirling Speed?
Ans. In Solid mechanics, in the field of rotor dynamics, the critical speed is the theoretical angular velocity which excites the natural frequency of a rotating object, such as a shaft, propeller or gear. As the speed of rotation approaches the objects natural frequency, the object begins to resonate which dramatically increases system vibration. The resulting resonance occurs regardless of orientation. Whirling Speed is due to the unbalanced forces acting on a rotating shaft.

2. How a Diesel Engine Works as Generator?
Ans. Diesel engine is a prime mover, for a generator, pump, and for vehicles etc. generator is connected to engine by shaft. Mostly in thermal power plat, there is an engine is used to drive generator to generate power.

3. Explain Second Law of Thermodynamics?
Ans. The entropy of the universe increases over time and moves towards a maximum value.

4. Compare Brayton Cycle and Otto Cycle?
Ans. The heat addition and rejection processes in Otto cycle are of constant volume, whereas in Brayton cycle, they are of constant pressure. Otto  cycle  is  the  ideal  cycle  for  spark  ignition  engines. Brayton cycle is the ideal cycle for gas power turbines.

5. What is the purpose of Scrapper Ring?
Ans. Scrap the excess lube oil from the cylinder walls. There by preventing oil from entering combustion zone.


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50 Mechanical Engineering Interview Question and Answer

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Tuesday, 16 September 2014

TOYOTA DEVELOPS HIGH EFFICIENCY FREE PISTON COMBUSTION ENGINE TO POWER ELECTRIC VEHICLE