Here i am sharing some mechanical parts industrial drawing solely for practice and understanding.
Thursday, 19 September 2013
Wednesday, 7 August 2013
Here i am sharing the simple marine engine; 9 hp; for small ship:
Marine engine and its parts ( please enlarge to view clearly)
Description of important parts:
- Cylinder head: In an internal combustion engine, the cylinder head (often informally abbreviated to just head) sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, and that allow the exhaust to escape. The head can also be a place to mount the valves, spark plugs, and fuel injectors.
- Intake valve & Exhaust valve: The valves through which fresh fuel enters into the combustion chamber is called intake valve and valve through which residual gases leave are called exhaust valve. These valves are controlled by CAM shaft.
- Valve rocker arm: Generally referred to within the context of the internal combustion engine of automotive, marine, motorcycle and reciprocating aviation engines, the rocker arm is an oscillating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it.
- Pre-combustion chamber: This chamber is located at the cylinder head and is connected to the engine cylinder by small holes. It occupies 40% of the total cylinder volume. During the compression stroke, air from the main cylinder enters the pre-combustion chamber. At this moment, fuel is injected into the pre-combustion chamber and combustion begins. Pressure increases and the fuel droplets are forced through the small holes into the main cylinder, resulting in a very good mix of the fuel and air. The bulk of the combustion actually takes place in the main cylinder. This type of combustion chamber has multi-fuel capability because the temperature of the pre-chamber vaporizes the fuel before the main combustion event occurs.
- Intake Silencer: It serves the purpose of silencing the air intake in engine.
- Mixing Elbow: Its function is to cool the engine exhaust gases by mixing them with the cooling water discharged from the engine heat ex-changer It requires no regular maintenance, but neither should it be completely forgotten. Over time, the exhaust mixer elbow can become restricted with accumulated soot from the engine exhaust, resulting in increased exhaust gas back pressure and loss of engine power.
- Camshaft: A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.
- Tappet: A tappet is a projection which imparts a linear motion to some other component within a mechanism.
- Pushrod: An overhead (OHV) engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block (usually beside and slightly above the crankshaft in a straight engine or directly above the crankshaft in the V of a V engine), and uses pushrods or rods to actuate rocker arms above the cylinder head to actuate the valves.
- Piston: In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod.
- Connecting rod: In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts reciprocating motion into rotating motion.
- Crankshaft: The crankshaft, sometimes abbreviated to crank, is the part of an engine that translates reciprocating linear piston motion into rotation. To convert the reciprocating motion into rotation, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to which the "big ends" of the connecting rods from each cylinder attach.
- Flywheel: A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by applying torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.
Friday, 31 May 2013
Mechanical engineering interview questions:
Que: What is bending moment?
Ans: When a moment is applied to bend an element, a bending moment exists in the element.
Que: What are the points in the Stress Strain curve for Steel?
Ans: Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.
Que: Define Reynolds number?
Ans: Reynolds number is the ratio of inertial force and viscous force. It is a dimensionless number. It determines the type of fluid flow.
Que: What is a Newtonian fluid?
Ans: A Newtonian fluid possesses a linear stress strain relationship curve and it passes through the origin. The fluid properties of a Newtonian fluid do not change when any force acts upon it.
Que: How many Joules is 1 BTU?
Ans: 1 BTU is equal to 1055.056 joules.
Que: What is PS?
Ans: PS is Pferdestarke, the German unit for Horsepower.
Que: Explain Otto cycle?
Ans: Otto cycle can be explained by a pressure volume relationship diagram. It shows the functioning cycle of a four stroke engine. The cycle starts with an intake stroke, closing the intake and moving to the compression stroke, starting of combustion, power stroke, heat exchange stroke where heat is rejected and the exhaust stroke. It was designed by Nicolas Otto, a German engineer.
Que: Explain the nomenclature of a 6203-ZZ bearing?
Ans: 6 is the type code, which shows it is a single-row ball bearing, 2 is the series, means light, 03 is the bore, which is 17 mm and ZZ is the suffix meaning double shielded bearing.
Que: What is Gear ratio?
Ans: It is the ratio of the number of revolutions of the pinion gear to one revolution of the idler gear.
Que: What is Annealing?
Ans: It is a process of heating a material above the re-crystallization temperature and cooling after a specific time interval. This increases the hardness and strength if the material.
Que: What is bending moment?
Ans: When a moment is applied to bend an element, a bending moment exists in the element.
Que: What are the points in the Stress Strain curve for Steel?
Ans: Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.
Que: Define Reynolds number?
Ans: Reynolds number is the ratio of inertial force and viscous force. It is a dimensionless number. It determines the type of fluid flow.
Que: What is a Newtonian fluid?
Ans: A Newtonian fluid possesses a linear stress strain relationship curve and it passes through the origin. The fluid properties of a Newtonian fluid do not change when any force acts upon it.
Que: How many Joules is 1 BTU?
Ans: 1 BTU is equal to 1055.056 joules.
Que: What is PS?
Ans: PS is Pferdestarke, the German unit for Horsepower.
Que: Explain Otto cycle?
Ans: Otto cycle can be explained by a pressure volume relationship diagram. It shows the functioning cycle of a four stroke engine. The cycle starts with an intake stroke, closing the intake and moving to the compression stroke, starting of combustion, power stroke, heat exchange stroke where heat is rejected and the exhaust stroke. It was designed by Nicolas Otto, a German engineer.
Que: Explain the nomenclature of a 6203-ZZ bearing?
Ans: 6 is the type code, which shows it is a single-row ball bearing, 2 is the series, means light, 03 is the bore, which is 17 mm and ZZ is the suffix meaning double shielded bearing.
Que: What is Gear ratio?
Ans: It is the ratio of the number of revolutions of the pinion gear to one revolution of the idler gear.
Que: What is Annealing?
Ans: It is a process of heating a material above the re-crystallization temperature and cooling after a specific time interval. This increases the hardness and strength if the material.
Saturday, 25 May 2013
Mechanical Engineering Interview Questions:
Que: The purpose of jigs and fixtures are to: a. Increased production rate
b. Increased machining accuracy
c. Facilitate interchangeable manufacturing
d. Enable employ less skilled operators
e. All of the above
Ans: All of the above.
Que: Which one of the following methods produces gear by generating process
a. Hobbing
b. Casting
c. Punching
d. Milling
e. Broaching
Ans: Hobbing
Que: Tool life of the cutting tool is most affected by
a. Cutting speed
b. Tool geometry
c. Cutting feed and depth
d. Micro-structure of material being cut
e. Not using coolant and lubricant
Ans: Cutting speed
Que: Metal in machining operation is removed by
a. Tearing chips
b. Distortion of metal
c. Shearing the metal across a zone
d. Cutting the metal across a zone
e. Pushing the metal with tool
Ans: Shearing the metal across a zone.
Que: A feeler gauge is used to check
a. Radius
b. Screw pitch
c. Surface roughness
d. Unsymmetrical shape
e. Thickness of clearance
Ans: Thickness of clearance.
Que:The property of a material which enable it to resist fracture due to high impact loads is known as
a. Elasticity
b. Endurance
c. Strength
d. Toughness
e. Resilience
Ans: Toughness
Que: Spring index is
a. Ratio of coil diameter to wire diameter
b. Load required to produce unit deflection
c. Its capability of storing energy
d. Indication of quality of spring
e. Nothing
Ans: Ratio of coil diameter to wire diameter.
Que: Nodular iron has
a. High machinability
b. Low melting point
c. High tensile strength
d. Good fluidity
e. All of the above
Ans: All of the above.
Que: Explain the Second Law of Thermodynamics.?
Ans: The entropy of the universe increases over time and moves towards a maximum value.
Que: How do you measure temperature in a Wet Bulb Thermometer?
Ans: Wet bulb temperature is measured in a wet bulb thermometer by covering the bulb with a wick and wetting it with water. It corresponds to the dew point temperature and relative humidity.
Que: The purpose of jigs and fixtures are to: a. Increased production rate
b. Increased machining accuracy
c. Facilitate interchangeable manufacturing
d. Enable employ less skilled operators
e. All of the above
Ans: All of the above.
Que: Which one of the following methods produces gear by generating process
a. Hobbing
b. Casting
c. Punching
d. Milling
e. Broaching
Ans: Hobbing
Que: Tool life of the cutting tool is most affected by
a. Cutting speed
b. Tool geometry
c. Cutting feed and depth
d. Micro-structure of material being cut
e. Not using coolant and lubricant
Ans: Cutting speed
Que: Metal in machining operation is removed by
a. Tearing chips
b. Distortion of metal
c. Shearing the metal across a zone
d. Cutting the metal across a zone
e. Pushing the metal with tool
Ans: Shearing the metal across a zone.
Que: A feeler gauge is used to check
a. Radius
b. Screw pitch
c. Surface roughness
d. Unsymmetrical shape
e. Thickness of clearance
Ans: Thickness of clearance.
Que:The property of a material which enable it to resist fracture due to high impact loads is known as
a. Elasticity
b. Endurance
c. Strength
d. Toughness
e. Resilience
Ans: Toughness
Que: Spring index is
a. Ratio of coil diameter to wire diameter
b. Load required to produce unit deflection
c. Its capability of storing energy
d. Indication of quality of spring
e. Nothing
Ans: Ratio of coil diameter to wire diameter.
Que: Nodular iron has
a. High machinability
b. Low melting point
c. High tensile strength
d. Good fluidity
e. All of the above
Ans: All of the above.
Que: Explain the Second Law of Thermodynamics.?
Ans: The entropy of the universe increases over time and moves towards a maximum value.
Que: How do you measure temperature in a Wet Bulb Thermometer?
Ans: Wet bulb temperature is measured in a wet bulb thermometer by covering the bulb with a wick and wetting it with water. It corresponds to the dew point temperature and relative humidity.
Monday, 13 May 2013
Mechanical engineering interview questions:
Que:What is the importance of thermodynamics in the field of mechanical engineering ?
Ans:All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.
Que: How many laws of thermodynamics are there?
Ans: There are three laws of the thermodynamics:
First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in an isolated system, the total energy remains the same.
Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but notin equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will
eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.
Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.
Que: State law of conservation of energy ?
Ans: According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”
Que: Is boiler a closed system ?
Ans: yes, boiler is definitely a closed system.
Que: What is carnot engine?
Ans: It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which follows the Carnot cycle and provides 100% efficiency.
Que:which formula forms a link between thermodynamics and electro-magnetism?
Ans: Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics and electromagnetism.
ΔHs/R = [∂ lnp /∂ (1/T)]x
Que:Which is the hardest compound known?
Ans: diamond.
Que:What is hess law?
Ans:According to the Hess law the energy transfer is simply independent of the path being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.
Que: Which engine is more efficient diesel engine or petrol engine?
Ans: Diesel engine
Que:What is the importance of thermodynamics in the field of mechanical engineering ?
Ans:All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.
Que: How many laws of thermodynamics are there?
Ans: There are three laws of the thermodynamics:
First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in an isolated system, the total energy remains the same.
Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but notin equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will
eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.
Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.
Que: State law of conservation of energy ?
Ans: According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”
Que: Is boiler a closed system ?
Ans: yes, boiler is definitely a closed system.
Que: What is carnot engine?
Ans: It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which follows the Carnot cycle and provides 100% efficiency.
Que:which formula forms a link between thermodynamics and electro-magnetism?
Ans: Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics and electromagnetism.
ΔHs/R = [∂ lnp /∂ (1/T)]x
Que:Which is the hardest compound known?
Ans: diamond.
Que:What is hess law?
Ans:According to the Hess law the energy transfer is simply independent of the path being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.
Que: Which engine is more efficient diesel engine or petrol engine?
Ans: Diesel engine
Saturday, 11 May 2013
Mechanical engineering interview questions:
Que: What is the difference between generator and invertor ?
Ans: An inverter is only effective if there is already a source of electrical energy. It cannot generate
its own. It can simply convert electrical energy that is already there. On the other hand, a traditional generator cannot make AC current into DC current.
Que: What is the difference between qualitative and quantitative research ?
Ans: Quantitative research involves gathering data that is absolute, such as numerical data, so that it can be examined in as unbiased a manner as possible.
Qualitative research may yield stories, or pictures, or descriptions of feelings and emotions. The interpretations given by research subjects are given weight in qualitative research, so there is no seeking to limit their bias. At the same time, researchers tend to become more emotionally attached to qualitative research, and so their own bias may also play heavily into the results.
Que: Difference between adsorption and absorption ?
Ans: In absorption, one substance (matter or energy) is taken into another substance. But in adsorption only the surface level interactions are taking place.
Que: Difference between liquid and aqueous ?
Ans:
Ans:
Ans:
Que: why sound is faster in warm air ?
Ans: The speed of sound in air cair = 331.3 + (0.66 x T) m/s, where T is the temperature in °C.
The speed of sound is proportional to gas temperature and inversely proportional to its
molar mass.
Sound is transferred by collisions of molecules. Therefore sound waves will travel faster on warm air because collisions of molecules of air in warm air is greater.
Que: How Cavitation can be eliminated in a pump ?
Ans: Cavitation means bubbles are forming in the liquid.
Ans: 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.
Que: Why centrifugal pump not called positive displacement type of pump ?
Ans: 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.
Que: Why centrifugal pump is called high discharge pump ?
Ans: Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of the impeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate. It is given in the following formulae:
Centrifugal force F= (M*V2)/R.
Where,
M-Mass
V-Velocity
R-Radius
Que: why cavitation will occur in centrifugal pump and not in displacement pump ?
Ans: 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.
Que: What is the difference between generator and invertor ?
Ans: An inverter is only effective if there is already a source of electrical energy. It cannot generate
its own. It can simply convert electrical energy that is already there. On the other hand, a traditional generator cannot make AC current into DC current.
Que: What is the difference between qualitative and quantitative research ?
Ans: Quantitative research involves gathering data that is absolute, such as numerical data, so that it can be examined in as unbiased a manner as possible.
Qualitative research may yield stories, or pictures, or descriptions of feelings and emotions. The interpretations given by research subjects are given weight in qualitative research, so there is no seeking to limit their bias. At the same time, researchers tend to become more emotionally attached to qualitative research, and so their own bias may also play heavily into the results.
Que: Difference between adsorption and absorption ?
Ans: In absorption, one substance (matter or energy) is taken into another substance. But in adsorption only the surface level interactions are taking place.
Que: Difference between liquid and aqueous ?
Ans:
- Liquid is a state of matter, while aqueous is a special type of liquid formed by dissolving a compound in water.
- All aqueous solutions are liquids, but not all liquids are aqueous solutions.
Ans:
- Vapour can turn back and forth into liquid and solid states but a gas cannot.
- Gases cannot be see while vapours are visible.
- Vapours settle down on ground while gases do not.
Ans:
- The melting point is a defined for solids when it transfers from solid state to liquid state.
- The boiling point is defined for liquids for a state change from liquid to gas.
- Boiling point is highly dependent on the external pressure whereas the melting point is independent of the external pressure.
Que: why sound is faster in warm air ?
Ans: The speed of sound in air cair = 331.3 + (0.66 x T) m/s, where T is the temperature in °C.
The speed of sound is proportional to gas temperature and inversely proportional to its
molar mass.
Sound is transferred by collisions of molecules. Therefore sound waves will travel faster on warm air because collisions of molecules of air in warm air is greater.
Que: How Cavitation can be eliminated in a pump ?
Ans: 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.
Ans: 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.
Que: Why centrifugal pump not called positive displacement type of pump ?
Ans: 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.
Que: Why centrifugal pump is called high discharge pump ?
Ans: Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of the impeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate. It is given in the following formulae:
Centrifugal force F= (M*V2)/R.
Where,
M-Mass
V-Velocity
R-Radius
Que: why cavitation will occur in centrifugal pump and not in displacement pump ?
Ans: 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.
Friday, 10 May 2013
Mechanical engineering interview questions:
Que: what is the other name of micrometer and vernier caliper?
Ans: micrometer's other name is screw gauge & vernier caliper's other name is slide caliper.
Que: what is flash-point?
Ans: flash-point is the lowest temperature at which the vapor of combustible liquid can be ignited in air.
Que: what is the difference between impulse turbine and reaction turbine?
Ans: » In impulse turbine, jet is used to create impulse on blades which rotates the turbine and in reaction turbine, no jet is used pressure energy is converted into kinetic energy.
» In impulse turbine fluid enter & leaves with same energy, but in reaction turbine fluid enter with pressure energy and leaves with kinetic energy.
Que: What is the difference between BSP thread and BSW thread?
Ans: 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 Whit-worth (BSW) is one of a number of imperial unit based screw thread standards which use the same bolt heads and nut hexagonal sizes.
Que: What is refrigerant?
Ans: Any substance that transfers heat from one place to another, creating a cooling effect. water is the refrigerant in absorption machines.
Que: The amount of carbon present in cast Iron?
Ans: Carbon is basically present in the form of cementite in cast iron.Its percentage lies in the range of 2.03-6.67(% by weight of cementite for Cast Iron.If the amount is less than the above range than it is stainless steel.
Que: What loads are considered while designing nuts and bolts ?
Ans: Shear loads and crushing loads.
Que: What is the effect of reheat on rankine cycle?
Ans: Its efficiency increases.
Que: Why are the head gaskets blown ?
Ans: Normally head gasket blows, when the engine overheats and they can also blow from incorrect installation or poor design. Head gaskets expand and contract according to engine temperature, these cycles may happen after a long period of time, causes the gasket to fail. If you’re replacing the gasket, check the engine block, and head for warping. Follow proper cleaning and torque specifications during assembly.
Que: What is the difference between humidifier and vaporizer ?
Ans: The basic difference between humidifiers and vaporizers is that humidifiers disperse cool mist
into the air, and vaporizers heat the water to disperse hot steam. Humidifiers are normally used in cooler climates, when due to the usage of heater, the air in the house becomes too dry for comfort and also, it becomes very difficult to breathe. Humidifiers release cool moisture droplets into the air.
Vaporizers also help in moistening the dry air in the house, but vaporizers release hot vapor into the air. There is a heating element in the vaporizers, which help in releasing steam. Vaporizers heat the water and then release vapors.
The basic difference between them is that one emits cold vapors, while the other one emits hot vapors.
Mechanical engineering interview questions:
Q. What if the gasoline is used in diesel engine? Diesel engine will work?
Ans. 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 and it may blast.
Q. Which mechanism is used in automobile gearing system?
Ans. Differntial mechanism.
Q. Why different types of sound are produced in different bikes though they all ran on SI engine?
Ans. Engine specifications are different in different manufacturer like bore diameter(cc), ignition timing. Also the exhaust passage take more responsible for sound.
Q. 1HP= how much watt ?
Ans. 746.2 watt.
Q. How to calculate bearing number to diameter of inner and outer?
Ans. Divide shaft diameter size by 5, it will give last two digits of the bearing number and according to type of load we have to choose the type of bearing and that will give prior no. Of the bearing .
Q. Define octane and cetane number?
Ans. Octane number: 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 number: cetane number is defines as the percentage, by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthaline. It is measure of rating of CI engine.
Q. Poissons ratio is higher in rubber/steel/wood ?
Ans. When material is compressed in one direction, it usually tends to expand in the other two directions perpendicular to the direction of compression. This phenomenon is called the poissons effect. Poisson's ratio is 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.
Q. The fatigue life of the part can be improved by?
Ans. Improving the surface finish by polishing and providing residual stress by shot peening.
Q. When crude oil is heated which hydro-carbon comes first.?
Ans. Natural gas ( gasoline) i.e. at 20 degree celsius.
Q. Difference between technology and engineering?
Ans. Engineering is application of science. Technology shows various methods of engineering. A bridge can be made using beams to bear the load,by an arc or by hanging in a cable; all shows different technology but comes under civil engineering and science applied is law of force/load distribution.
Q. What if the gasoline is used in diesel engine? Diesel engine will work?
Ans. 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 and it may blast.
Q. Which mechanism is used in automobile gearing system?
Ans. Differntial mechanism.
Q. Why different types of sound are produced in different bikes though they all ran on SI engine?
Ans. Engine specifications are different in different manufacturer like bore diameter(cc), ignition timing. Also the exhaust passage take more responsible for sound.
Q. 1HP= how much watt ?
Ans. 746.2 watt.
Q. How to calculate bearing number to diameter of inner and outer?
Ans. Divide shaft diameter size by 5, it will give last two digits of the bearing number and according to type of load we have to choose the type of bearing and that will give prior no. Of the bearing .
Q. Define octane and cetane number?
Ans. Octane number: 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 number: cetane number is defines as the percentage, by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthaline. It is measure of rating of CI engine.
Q. Poissons ratio is higher in rubber/steel/wood ?
Ans. When material is compressed in one direction, it usually tends to expand in the other two directions perpendicular to the direction of compression. This phenomenon is called the poissons effect. Poisson's ratio is 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.
Q. The fatigue life of the part can be improved by?
Ans. Improving the surface finish by polishing and providing residual stress by shot peening.
Q. When crude oil is heated which hydro-carbon comes first.?
Ans. Natural gas ( gasoline) i.e. at 20 degree celsius.
Q. Difference between technology and engineering?
Ans. Engineering is application of science. Technology shows various methods of engineering. A bridge can be made using beams to bear the load,by an arc or by hanging in a cable; all shows different technology but comes under civil engineering and science applied is law of force/load distribution.
Sunday, 5 May 2013
CRDI: Widely know as CRDi,
CRDe, DICOR and Tdi and so on by various manufacturers, it has been marked as
the technology for this week. The reason, as we can see all around us the fact
that the modern diesel is no longer a smoke breathing rattling workhorse, but
is the biggest buzzword in the Indian car market. This technology, coupled with
rising fuel prices of course has made a diesel car both economical and
enjoyable.
Solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomisation. In order to lower engine noise the engine's electronic control unit can inject a small amount of diesel just before the main injection event ("pilot" injection), thus reducing its explosiveness and vibration, as well as optimising injection timing and quantity for variations in fuel quality, cold starting, and so on. Some advanced common rail fuel systems perform as many as five injections per stroke.
Common rail engines require no heating up time and produce lower engine noise and emissions than older systems.
Diesel engines have historically used various forms of fuel injection. Two common types include the unit injection system and the distributor/inline pump systems. While these older systems provided accurate fuel quantity and injection timing control they were limited by several factors:
First conceived by
Marelli in 1987 but it wasn't until Fiat acquired the technology that it got
tested on one of their cars in 1992. The process was later sent to Bosch group
for implementation in the commercial market. The most important contributor to
its effectiveness remains with the common rail. Which basically means same fuel
line. That is, when fuel gets injected into say cylinder 1; there is virtually
no pressure loss at the rest of the rail. This in turn means that there is
always adequate pressure available for the injection. Common rail technology
makes use of 2 pumps in order to bring the fuel up to high pressures of up to
1350 bar. During the first stage, an electronic pump draws required amount of
fuel from the fuel tank; this low-pressure pump is governed by the engine
management system. The speed of the pump is determined by driver inputs and
other information obtained from sensors. This has allowed Common rail systems
to reduced emissions due to absence of unburnt fuel. The second stage of
pumping is done with the help of a mechanical pump that is coupled with the
crankshaft and geared in order that it may rotate at half engine speed. The
fuel now goes to an accumulating duct (rail), where these pressures maybe maintained.
This tank allows for the maintaining of this constant pressure even during the
injection. The injection maybe carried out using electromagnetic valves, which
govern the exact amount of fuel for injection. Leaks occurring at the pump,
leaks for opening the valves etc are returned back to the fuel tank. Which in
turn results in zero wastage of fuel.
When common rail technology is integrated with turbo chargers or superchargers the power delivered by a diesel engine may well exceed that attained by a similar sized petrol engine. Today's manufacturers are embracing this technology due to all the advantages it holds. At the rate with which this technology is catching up, Diesel definitely holds the key as far as development in efficiency is .
When common rail technology is integrated with turbo chargers or superchargers the power delivered by a diesel engine may well exceed that attained by a similar sized petrol engine. Today's manufacturers are embracing this technology due to all the advantages it holds. At the rate with which this technology is catching up, Diesel definitely holds the key as far as development in efficiency is .
Principle:
Solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomisation. In order to lower engine noise the engine's electronic control unit can inject a small amount of diesel just before the main injection event ("pilot" injection), thus reducing its explosiveness and vibration, as well as optimising injection timing and quantity for variations in fuel quality, cold starting, and so on. Some advanced common rail fuel systems perform as many as five injections per stroke.
Common rail engines require no heating up time and produce lower engine noise and emissions than older systems.
Diesel engines have historically used various forms of fuel injection. Two common types include the unit injection system and the distributor/inline pump systems. While these older systems provided accurate fuel quantity and injection timing control they were limited by several factors:
- They were cam driven and injection pressure was
proportional to engine speed. This typically meant that the highest
injection pressure could only be achieved at the highest engine speed and
the maximum achievable injection pressure decreased as engine speed
decreased. This relationship is true with all pumps, even those used on
common rail systems; with the unit or distributor systems, however, the
injection pressure is tied to the instantaneous pressure of a single pumping
event with no accumulator and thus the relationship is more prominent and
troublesome.
- They were limited on the number of and timing of
injection events that could be commanded during a single combustion event.
While multiple injection events is possible with these older systems, it
is much more difficult and costly to achieve.
- For the typical distributor/inline system the
start of injection occurred at a pre-determined pressure (often referred
to as: pop pressure) and ended at a pre-determined pressure. This
characteristic results from "dummy" injectors in the cylinder
head which opened and closed at pressures determined by the spring preload
applied to the plunger in the injector. Once the pressure in the injector
reached a pre-determined level, the plunger would lift and injection would
start.
In common rail systems a high pressure pump
stores a reservoir of fuel at high pressure — up to and above 2,000 bars
(29,000 psi). The term "common rail" refers to the fact that all
of the fuel injectors are supplied by a common fuel rail which is nothing more
than a pressure accumulator where the fuel is stored at high pressure. This accumulator supplies multiple fuel injectors with high pressure fuel. This simplifies the purpose of the high pressure pump in that it only has to maintain a commanded pressure at a target (either mechanically or electronically controlled). The fuel injectors are typically ECU-controlled. When the fuel injectors are electrically activated a hydraulic valve (consisting of a nozzle and plunger) is mechanically or
hydraulically opened and fuel is sprayed into the cylinders at the desired
pressure. Since the fuel pressure energy is stored remotely and the injectors
are electrically actuated the injection pressure at the start and end of
injection is very near the pressure in the accumulator (rail), thus producing a
square injection rate. If the accumulator, pump, and plumbing are sized
properly, the injection pressure and rate will be the same for each of the
multiple injection events.
The internal combustion engine (ICE) finds its place in the market with latest design modifications in various components to improve efficiency, economy and overall performance. However, one component has remained unchanged in the internal combustion engine development i.e., the camshaft, has been the primary means of controlling the valve actuation and timing, and therefore, influencing the overall performance of the vehicle. Cam-less technology is capturing the future of internal combustion engines. It has been known to man that if valves could be controlled independently in an Internal Combustion Engine then there would be benefits like increased power, reduced emissions and increased fuel economy. In the cam-less technology valve motion is operated by valve actuators of electro-mechanical and electro-hydraulic type.
Introduction: Cams, lifters, push-rods all these things have up until now been associated with the internal combustion engine. But the end is near or these lovely shiny metal objects that comprise the valve train
hardware in your pride and joy. Camless engine technology is soon to be a reality for mass-produced vehicles. In the camless valvetrain, the valve motion is controlled directly by a valve actuator - there's no camshaft or connecting mechanisms. Various studies have shown that a camless valve train can eliminate many otherwise necessary engine design trade-offs.Automotive engines equipped with camless valvetrains of the electrohydraulic and electro-mechanical type have been studied for over twenty years, but production vehicles with such engines are still not available.
Cam-less Valve-train Operation: The types of camless variable valve actuating systems being developed can be classed in two groups: electrohydraulic and electromechanical. When it comes to electromechanical valve trains, there are several designs that are being trialed. Most developers are using the conventional poppet valve system (ie valves that look the same as in today's engines) but an alternative is a ball valve set up. Both use electromagnets in one way or another to open and close the valve. Originally created for the Apollo space program, the electrohydraulic valve actuator works by sending pressurised hydraulic fluid to the engine valve to move it open or closed. These systems are mainly retain poppet valves and are preferred by truck engine manufacturers.
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