MULTIPLE CHOICE QUESTIONS ON ENGINE LUBRICATION SYSTEM !!

1-Lubricating oil

(A) Minimizes wear in moving parts

(B) Helps in keeping the parts cool

(C) Washes away and carries away dirt

(D) All of the above

(Ans: D)

2-Viscosity index (VI) is a measure for the change of viscosity with change in

(A) Temperature

(B) Pressure

(C) Volume

(D) All of the above

(Ans: A)

3-The following type of Lubrication system is used in two stroke engines

(A) Petroil (mist) system

(B) Wet sump system

(C) Dry sump system

(D) All of the above

(Ans: D)

4-In the following system, lubricating oil is carried in separate tanks from where it is fed to the engine

(A) Mist lubrication system

(B) Wet sump system

(C) Dry sump system

(D) Splash system

(Ans: C)

5-The following type of Lubrication system is used in Aircraft Engines

(A) Mist lubrication system

(B) Wet sump system

(C) Dry sump system

(D) Splash system

(Ans: C)

6-The following type(s) of Oil pump(s) is (are) used in Engine Lubrication system

(A) Gear type

(B) Rotor type

(C) Plunger type

(D) All of the above

(Ans: D)

7-The following is (are) oil pressure gauge(s)

(A) Pressure expansion type

(B) Electric type

(C) both (A) and (B)

(D) None of the above

(Ans: C)

8-The purpose of crankcase ventilation is to

(A) remove harmful particles from the engine

(B) provide proper lubrication to the engine

(C) provide air for combustion to the engine

(D) all of the above

(Ans: A)

9-The following part(s) is(are) lubricated by splash system

(A) Piston and piston rings

(B) Tappets

(C) Cams on camshaft

(D) All of the above

(Ans: D)

10-The following part is not lubricated by Pressure feed system

(A) Timing gears

(B) Valve rods and Push rods

(C) Rocker arms

(D)  Main bearings of crankshaft

(Ans: B)

INTERVIEW QUESTIONS OF PRODUCTION TECHNOLOGY !!

1) What do you mean by Smelting ?
 
Process of extraction of iron is called Smelting.

2) What do you understand by Specific Gravity and Tenacity ?

Specific Gravity . It is the ratio of the mass of 1cubic cm. of a substance to the mass of the same capacity of water.

• Tenacity .It is the property of metal due to which a metal becomes strong enough to resist the pulling force.

3) Define the following metal properties (a) Machinability (b)Malleability

(a) Machinability is the property of metal due to which a metal can easily be cut by cutting tools to obtain good surface finish. E.g.: Brass, Mild steel

• (b) Malleability is the property of the metal on account of which it can be extended in all directions by hammering or rolling. E.g.: Tin, Lead

4) Define Hardness of the metal ?

It is the property of the metal which makes a metal capable to resist surface penetration by other metals .Hard metals are High carbon steel and High speed steel.

5) What is the Toughness of metal ?

Toughness is the property of metal due to which without fracture a metal is able to withstand bending or torsion. Mild steel and wrought iron are tough metals.

6) Define the following properties of metal : (a) Fusibility (b) Stiffness (c) Ductility

Fusibility. It is the property of metal due to which a metal becomes fluid when it is heated.
Stiffness. It is the property of metal due to which a metal is capable of resisting deflection due to an externally applied load.
Ductility. It is the property of metal due to which a metal can be drawn into the form of wires without rupture.

7) Why are cast iron seasoned before machining ?

For easy machining and saving the cutting edge of the tool.

8) How does carbon affects the properties of steel ?

If carbon content is higher the degree of hardness is more and the melting point is lower, If carbon percentage is lower it is easy to forging and forge welding.

9) Why are machine beds made of cast iron ?

Because it has more compressive strength and negligible shrinkage. It can easily cast into any integral shape, wear resisting and can absorb vibrations.

10) What is the difference between Wrought iron, Cast iron and Pig iron ?

Wrought iron contains less than 0.1% carbon and this is a product of puddling furnace. Cast iron is produced from cupola furnace. It contains 3­3.5% carbon in combined or free state. Pig iron is an iron carbon alloy contains 3­5% carbon along with impurities like manganese, sulphur and phosphorous. It is a product of blast furnace.

TIPS TO REMEMBER THERMODYNAMIC PROCESSES EXPLAINED !!

In thermodynamics you might get confused with various thermodynamic processes like isobaric, isochoric, isothermal, isetropic. This video explains various tricks to remember the meaning of various thermodynamic processes.

FOUR WHEEL DRIVE VS ALL WHEEL DRIVE EXPLAINED !!

The 4WD and AWD are pretty much same, but have some variations each works best under certain conditions.

Four Wheel Drive:

• It’s the oldest one, which has two options in terms of how and when torque is supplied to each wheel called Full time 4WD and Half time 4WD. Power from the engine goes to transfer case, which splits the power between the front and rear axles so that torque is evenly applied to each wheel
• Its axles doesn’t rotate at the same speed, the option is available to choose what we need whether the torque needed for 2 wheels or 4 wheels.
• It’s good for Off road vehicles, Pickup trucks, terrain running vehicles where torque plays major role.
• It has locking differential option which gives more traction power to the wheels in off roads.
• This rugged technology has an option to turn off the drive to improve fuel economy.
• It might be dangerous once back on Tarmac from off road.
• Used in Jeeps, Landrovers, Pickup trucks.

All wheel drive:

• AWD is a car system while 4WD is a truck system, the recent innovation which is AWD drive system is on all the time used in all the cars like Audi, Nissan GTR, Mercedes-Benz E63 AMG .These are all good examples for AWD.
• ECU(Electronic control Unit) Plays a major role in the AWD system sensors on each wheel monitor traction, wheel speed, and several other data points and decide to send the power to which wheel depends to maximise the grip and driveability.
• This best AWD sends the power to each wheel using a front rear torque - split system cutting the power from the wheel to the least traction. Most of the time rear wheels have the power to move the vehicle forward and from front wheels moves freely to improve fuel economy.
• The latest technology in AWD use variable torque distribution system.
• Provides increased grip and control under all road condition, gives sportier handling and traction to a broader range of cars. Good in snowy roads, performance oriented cars.
• Not good for off road and fuel economy is less.

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6 THINGS YOU MUST KNOW ABOUT YOUR CAR'S AIR CONDITIONER !!

1) Important Air Conditioner Terms

SEER: Seasonal Energy Efficiency Ratio. Just remember this, higher the SEER, more will be the efficiency of unit, resulting in a lower operating cost.

Blower (Blower Motor): The motor and fan assembly mounted near the evaporator that draws air over the evaporator. In automotive applications, the blower motor may draw outside or inside air, depending on control settings.

Charging: Adding refrigerant to a system.

Flushing: A process of cleaning the internal components of an A/C system. This process requires the removal of refrigerant. This process is used to remove contamination and corrosion from the system.

Compressor: The pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again.

Refrigerant Oil: Highly refined oil that is free of contaminants. Used in the A/C system for the sole purpose of maintaining compressor lubrication.

Ductwork: A pipe or conduit through which air is supplied.

Evaporator coil: It is the network of tubes that are filled with refrigerant. It is located inside the home within the indoor unit and takes heat and moisture out of the indoor air when liquid refrigerant evaporates.

2) How Air Conditioner Works?

Air conditioners use the basic refrigeration process to cool indoor air. However, conditioning is different from refrigeration as it also regulates air humidity, quality, and speed besides the temperature. When a liquid (refrigerant) converts into gas, it absorbs heat, and this is called evaporation or phase conversion. This occurs in the evaporator part of the system. Whereas, when the refrigerant is condensed, it turns back into liquid, and this happens in the condenser. Other key components include expansion valve, compressor, and the collector. Air conditioners use phase conversion by forcing refrigerants to evaporate and condense in a closed system of coils repeatedly.

3) Purpose Of Air Conditioner Filters

Filters remove particles from the air to keep the dust out of your car AC’s air ducts. Make sure you change your ‘dirt air filter’ every 1-3 months depending on your surroundings and usage. Not changing your air filters can bring problems like dirty air, reduced airflow, increased fuel consumption, low quality of cooling, and frozen coils.

4) Maintenance Of Air Conditioner

Your air conditioner becomes less efficient, weak, and unreliable when it is not taken care of. This will cause headaches for you and probably increase repair bills in case you ignore it up to the point of busting it.

Just like the rest of your car, your air conditioner needs regular service. If the air conditioner is not running properly, it may be working too hard. This could result in inconsistent air temperatures, heating of the car, and reduced comfort.

If you need more convincing, most manufacturers require routine maintenance for their warranty on the air conditioners to remain valid. So go get your car AC checked up in case you feel it is not working up to the mark.

5) Importance Of Air Ducts

It is important to have your car’s air ducts cleaned and checked for leaks. Sometimes dust or leaves get stuck up in the air ducts, wrecking havoc with your cooling system and the blower. A clean air duct system will help your car AC last longer by removing contaminants that decrease your system’s efficiency and consume more fuel.

6) Increasing Air Conditioner Efficiency

Keeping your air conditioner maintained and tip top is the best thing you can do for its performance and your wallet as well. Sealing leaky ducts, keeping the right refrigerant charge, increasing your thermostat by a few degrees, replacing filters, cleaning coils, using car window tinting, parking in the shadow, insulating the air ducts are all great ways that help to increase the energy efficiency of air conditioner.

IRON CABLES ARE FABRIC INSULATED !! WHY??

Electric irons and certain other kinds of heating appliances have a high risk of the power cord being exposed to very high temperatures, by direct contact with the heating element. Plastic or rubber materials work great as electrical insulators, but many of them acts very poorly and fail in undesirable ways when exposed to high temperatures.

In order to prevent this kind of hazardous failure, the cord is sheathed with a material that has:

• good resistance to high temperatures
• low thermal conductivity, to protect the rubber electrical-insulating layers inside
• high flexibility

This kind of woven/braided fabric meets these requirements pretty well. The kind of kinking failure shown in the picture results from poor handling, and specifically too small of a bend radius.Also in case of direct contact with the heating element by mistake they do not fail (melt)immediately as in case of plastic or rubber.

DIFFERENCE BETWEEN SUPERCHARGER AND TURBOCHARGER EXPLAINED!!

Many times we have heard that, this car is supercharged or this is turbocharged. When we heard this, one question arises in our mind 
what is supercharged and what is turbocharged engine. Which one is  better between them. What are functions of these units. Today we will discuss all these answers and the main differences between them. -

Before discussing about these unit, first we should know about what is charge. When we talk about an engine the charge is used to identify amount of air and fuel mixture sucked into the cylinder during the intake stroke. So the charge is refereed as the mass of air-fuel mixture taken into the cylinder during intake stroke.

When we require more power than we need more charge into the cylinder. There are two ways of increasing charge of an engine. 

1. First one is to increase the engine size or cylinder size, so more air fuel mixture sucked and generate more power.

2. The other one uses a compressor which increase the density of charge and  draws more charge into the cylinder at high pressure so the more mass of air fuel mixture comes into the cylinder which generate more power. 

The second one is more convenient because it uses an smaller size engine to generate same power as the big one. And the other benefit is that this can be implemented in the old cars by adding a compressor unit. Both supercharger and turbocharger are  worked on same principle i.e. by using compressor. Turbocharger and supercharger both compresses the air and forces this compressed air into the engine cylinder. According to the air, large amount of fuel is injected into the cylinder, which produces more power. It is the basic principle of both turbocharger and supercharger. 

The main difference :-

Supercharger :-

Supercharger is an air compressor which is used to increase the power of an engine. Basically supercharger is a rotary compressor which is driven by  the crankshaft through a belt drive. This compressor is connected at the inlet manifold of the engine. As the engine rotate it rotate the supercharger which forces compressed air into cylinder. So the supercharger takes power from crankshaft to drive its compressor.

Turbocharger:-

Turbocharger is basically a combination of a turbine and a rotary compressor. The turbine is connected to the compressor and driven by the hot exhaust gases of the engine. So a turbocharge is a compressor which is driven by exhaust gases of engine which forces the compressed gases into the cylinder. 

So the main difference between supercharger and turbocharger is that supercharger takes power from the engine to drive its compressor whereas turbocharger takes power from exhaust gases to drive its compressor.