Base of Design

Base of Design.

Before design a 3D model, every engineering must understand the concept of the model and how is the mechanism work. This is the best process to build a 3D model. For example, using Transmission as the planning concept to build 3D, or applied Electrical component. This is convenience for assembly a structure and simulate the mechanism.

ALL WHEEL DRIVE

All Wheel Drive

• An AWD vehicle (short for All-wheel drive vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.It appears in everything from supercars with out-of-this-world performance like the Audi R8 to family crossovers and SUVs like the Volvo XC90.

Advantages

• As compared to rear wheel driven car, there is a faster and safer travelling due to good road holding on curves.
• Gives sportier handling and traction to a broader range of cars.
• A lower flat floor lines is provided due to dispensing with the propeller shaft resulting in lowering of centre of gravity.
• The engine, clutch, gear box and final drive are combined similar to the rear engine car. This provides a more comfortable drive due to final drive spring. 
• Good road adhesion is obtained due to a large part of the vehicle’s weight being carried on the driving wheels under normal conditions.

REAR ENGINE REAR WHEEL DRIVE

Rear engine rear wheel drive

• Rear-engine, Rear-wheel-drive layout places both the engine and drive wheels at the rear of the vehicle.
  

Advantages

• Better road adhesion preferably on steep hills and while accelerating with increased weight on the driving wheels.
• Generally a proportional part of weight of the car is transferred to the front wheels while braking. Therefore, due to the firm road surface contact maintained by rear engined car results in assistance to stopping of the vehicle.
• In this arrangement, front wheels are only for steering purposes.
• The necessaity of the propeller shaft is altogether eliminated due to the combination of engine, gear box and final drive. This also requires only one common oil sump.
• Good visibility and stream lining is provided by proper design of vehicle front.

FRONT ENGINE FRONT WHEEL DRIVE

Front engine front wheel drive

Front-wheel drive is the most common form of engine/transmission layout used in modern passenger cars, where the engine drives the front wheels only.In this layout a front mounted engine-clutch-gear box unit drives a beam type rear axle suspended on leaf sprints through a propeller shaft with two universal joints. Most front wheel drive vehicles today feature transverse engine mounting, though many in prior decades were positioned longitudinally instead.

Advantages

• Balanced weight distribution between the front and the rear wheels.
• Easy front wheel steering.
• Behind the rear seats, large luggage space is available.
• Accessibility to various components like engine, gearbox and rear axle is better in comparison to other layouts. The control linkages-accelerator, choke, clutch and gearbox are short and simple.
• Full benefits of the natural air stream created by vehicle’s movement is taken by the forward radiator resulting in reduced power losses from a large fan.
• Small length of the propeller shaft permits the angularity of the universal joints to be small and easily provided by simple types.

BEAM ENGINE

A Beam Engine is a type of steam engine where a pivoted overhead beam is used to apply the force from a vertical piston to a vertical connecting rod. This configuration, with the engine directly driving a pump, was first used by Thomas Newcomen around 1705 to remove water from mines in Cornwall. The efficiency of the engines was improved by engineers including James Watt who added a separate condenser, Jonathan Hornblower and Arthur Woolf who compounded the cylinders, and William McNaught (Glasgow) who devised a method of compounding an existing engine. Beam engines were first used to pump water out of mines or into canals, but could be used to pump water to supplement the flow for a waterwheel powering a mill.

BELT DRIVE

Belt Drives are widely used in many industries for power transmission. Since they are cheap and easy to maintain. However they are often a source of vibration due to misalignments, belt resonance, and belt wear.

The main purpose of belt drives is to transfer power between machines such as motor and fan. They are subject to rotary and push-pull motions with varying dynamic characteristics. Belts are friction drives, which mean they depend on friction between the belt and pulley/sheave to transmit power.

SPARK PLUG

A spark plug is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture by an electric spark, while containing combustion pressure within the engine.

IMPORTANT INTERVIEW QUESTION

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

• Large tyres provide larger surface area touching the ground, thus providing the more pulling power. Basically tractors have larger rear tyres because tractors don’t have to operate at higher speeds, thus getting the same ground speed with larger tyres. Moreover gear ratios don’t have to be as high as b/c of the tyres.

2.)What is kingpin offset? State some of its application.

• The kingpin offset is the part, basically called as pivot used in the steering of the vehicles. This offset helps in rotating of the steering and thus it’s very useful in steering mechanism of the cars.
• Applications: This is also used to measure scrub radius with the help of geometric parameters of wheel plane above and below ground level.
• It provides directional stability to the vehicles when it i combined with the caster.

3.)Explain the basic difference between BS2 and BS3 engine.

• The basic difference of BS2 and BS3 engines is the presence of catalytic convertor. Catalytic convertor is present in BS3 engine which helps in reducing the formation of HC and CO. While in BS2 engine, no catalytic convertor is present which forms HC and CO. Thus in BS3 engine there is no emission of harmful CO and HC. The full form of BS is bharat stage, which is a standard of emission in India.

Air Force Common Admission Test AFCAT

Air Force Common Admission Test AFCAT

Engineering Knowledge Test

Positive Displacement Pump (Lobe Pump)

A positive displacement pump causes a fluid to move by trapping a fixed amount of it then forcing (displacing) that trapped volume into the discharge pipe. Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, will produce the same flow at a given speed (RPM) no matter what the discharge pressure.
One practical difference between dynamic and positivedisplacement pumps is their ability to operate under closed valve conditions.
Positive displacement pumps physically displace the fluid; hence closing a valve downstream of a positive displacement pump will result in a continual build up in pressure resulting in mechanical failure of either pipeline or pump. Dynamic pumps differ in that they can be safely operated under closed valve conditions (for short periods of time).
It is called so because replacing equal quantity of liquid from cavity is called positive displacement.

HOW BRAKES STOP VEHICLES

HOW BRAKES STOP VEHICLES

Brakes are an energy-absorbing mechanism that converts vehicle movement into heat while stopping the rotation of the wheels.
All braking systems are designed to reduce the speed and stop a moving vehicle and to keep it from moving if the vehicle is stationary.

Service brakes are the main driver-operated brakes of the vehicle, and are also called base brakes or foundation brakes.
Most vehicles built since the late 1920s use a brake on each wheel. To stop a wheel, the driver exerts a force on a brake pedal. Force on the brake pedal pressurizes brake fluid in a master cylinder.

This hydraulic force (liquid under pressure) is transferred through steel lines and flexible brake lines to a wheel cylinder or caliper at each wheel. Hydraulic pressure to each wheel cylinder or caliper is used to force friction materials against the brake drum or rotor.
The heavier the vehicle and the higher the speed, the more heat the brakes have to be able to absorb.

Long, steep hills can cause the brakes to overheat, reducing the friction necessary to slow and stop a vehicle

Iron Carbon Phase Diagram

GLARE (Glass Laminate Aluminium Reinforced Epoxy)

GLARE (Glass Laminate Aluminium Reinforced Epoxy)

GLARE is a "Glass Laminate Aluminium Reinforced Epoxy" FML, composed of several very thin layers of metal (usually aluminium) interspersed with layers of glass-fibre "pre-preg", bonded together with a matrix such as epoxy. The uni-directional pre-preg layers may be aligned in different directions to suit the predicted stress conditions.

Although GLARE is a composite material,[1] its material properties and fabrication are very similar to bulk aluminum metal sheets. It has far less in common with composite structures when it comes to design, manufacture, inspection or maintenance. GLARE parts are constructed and repaired using mostly conventional metal material techniques.

Its major advantages over conventional aluminium are:
Better "damage tolerance" behaviour (especially impact and metal fatigue, as the elastic strain is larger than other metal material it can consume more impact energy. It is dented easier but has a higher penetration resistance )
Better corrosion resistance
Better fire resistance
Lower specific weight

Furthermore, it is possible to "tailor" the material during design and manufacture such that the number, type and alignment of layers can suit the local stresses and shapes throughout the aircraft. This allows the production of double-curved sections, complex integrated panels or very large sheets, for example.

While a simple manufactured sheet of GLARE will be more expensive than an equivalent sheet of aluminium, considerable production savings can be made using the aforementioned optimization. A structure properly designed for GLARE will be significantly lighter and less complex than an equivalent metal structure, and will require less inspection and maintenance and enjoy a much longer lifetime-till failure, making it a cheaper, lighter and safer option overall.

Applications
Besides the applications on the Airbus A380 fuselage, GLARE has multiple 'secondary' applications. GLARE is also the material used in the ECOS3 blast-resistant Unit Load Device. This is freight container shown to completely contain the explosion and fire resulting from a bomb such as that used over Lockerbie. Other applications include among others the application in the Learjet 45 and in the past also in cargo floors of the Boeing 737.

Current production
GLARE is currently produced by Cytec Engineered Materials in Wrexham, UK who supplies it to the Airbus A380 component manufacturing facilities at Stork Fokker in the Netherlands as well as at Airbus in Nordenham, Germany. Stork Fokker has opened a brand new facility next to its existing facilities in Papendrecht, the Netherlands. There Stork Fokker is able to produce Glare sheets of 4.5 x 11.5 m including the milling of doors windows etc. on a state-of-the-art 5-axis milling machine with a movable bed

TURBOCHARGER

TURBOCHARGER

A turbocharger,is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber.

The key difference between a turbocharger and a conventional supercharger is that a supercharger is mechanically driven by the engine, often through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by the engine's exhaust gas. Compared to a mechanically driven supercharger, turbochargers tend to be more efficient, but less responsive. Twincharger refers to an engine with both a supercharger and a turbocharger.

Turbochargers are commonly used on truck, car, train, aircraft, and construction equipment engines. They are most often used with Otto cycle and Diesel cycle internal combustion engines. They have also been found useful in automotive fuel cells

DIRECT PETROL INJECTION

DIRECT PETROL INJECTION

This diagram shows the layout of the Bosch direct injection system. Direct injection systems differ from conventional port injection in several ways.

The fuel supply system uses two fuel pumps – a conventional electrical fuel pressure pump (in the past dubbed a high pressure pump but now referred to in this system as a low pressure pump) and a mechanically-driven high pressure pump. The low pressure pump works at pressures of 0.3 – 0.5 MPa while the high pressure pumps boost this very substantially to 5 – 12 MPa.

The high pressure fuel is stored in the fuel rail that feeds the injectors. The fuel rail is made sufficiently large that pressure fluctuations within it are minimised as each injector opens. The pressure of the fuel in the injector supply rail is controlled by an electronically-controlled bypass valve that can divert fuel from the high pressure pump outlet back to its inlet. The fuel bypass valve is varied in flow by being pulse-width modulated by the Electronic Control Unit (ECU). A fuel pressure sensor is used to monitor fuel rail pressure.

This diagram shows a cross-sectional view of an injector. Compared with a conventional port fuel injection system, the fuel injectors must be capable of working with huge fuel pressures and also injecting large amounts of fuel in very short periods. The reason for the much reduced time in which the injection can be completed is due to the fact that all the injection must sometimes occur within just a portion of the induction stroke. Conventional port fuel injectors have two complete rotations of the crankshaft in which to inject the fuel charge – at an engine speed of 6000 rpm, this corresponds to 20 milliseconds. However, in some modes, direct fuel injectors have only 5milliseconds in which to inject the full-load fuel. The fuel requirements at idle can drop the opening time to just 0.4 milliseconds. Direct injection fuel droplets are on average only one-fifth the droplet size of traditional injectors and one-third the diameter of a human hair.

The very lean air/fuel ratios at which direct injection systems can operate results in the production of large quantities of oxides of nitrogen (NOx). As a result, direct injected cars require both a primary catalytic converter fitted close to the engine, and also a main catalytic converter - incorporating a NOx accumulator - that is fitted further downstream.

MULTIPOINT FUEL INJECTION

MULTIPOINT FUEL INJECTION

Fuel injection is a method or system for admitting fuel into the internal combustion engine.There are basically two ways of admitting fuel one is through carburetor and other is fuel injection system.But presently the most used injection system are MPFI in petrol engine and CRDI in diesel engine.

Multi point fuel injection is a system wherein fuel is injected into individual cylinders based on commands from "on board engine management system computer"-popularly known as Engine control unit.ECU receives feed back from several sensors like engine speed sensor, fly wheel position sensor, vehicle speed sensor, atmospheric temp. sensor, accelerator pedal position sensor intake airflow sensor. Then ECU control the correct amount of fuel to be injected and the proper time at which the fuel will be injected at any speed and load condition. This ensure maximum power output at minimum fuel.


MPFI systems are of three types, first is BATCHED in which fuel is injected to the cylinders in groups, without precisely bringing together to any particular cylinder’s intake stroke, the second one is simultaneous in which fuel is injected at the same time to all the cylinders and the third one is sequential in which injection is timed to coincide with each cylinder’s intake stroke.

ADVANTAGES OF MPFI

• More uniform air-fuel mixture will be supplied to each cylinder, hence the difference in power developed in each cylinder is minimum. 
• The vibrations produced in MPFI engines is very less, due to this life of the engine component is increased. 
• No need to crank the engine twice or thrice in case of cold starting as happen in the carburetor system. 
• Immediate response, in case of sudden acceleration and deceleration. 
• The mileage of the vehicle is improved. 
• More accurate amount of air-fuel mixture will be supplied in these injection system. As a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level. 

RACK AND PINION GEAR

RACK AND PINION GEAR

                   Rack and pinion gears are used to convert rotation into linear motion.The circular pinion engages teeth on a flat bar - the rack. Rotational motion applied to the pinion will cause the rack to move to the side, up to the limit of its travel.The rack and pinion arrangement is commonly found in the steering mechanism of cars or other wheeled, steered vehicles.A good example of a ‘rack and pinion’ gear system can be seen on trains that are designed to travel up steep inclines. The wheels on a train are steel and they have no way of griping the steel track. Usually the weight of the train is enough to allow the train to travel safely and at speed along the track. However, if a train has to go up a steep bank or hill it is likely to slip backwards. A ‘rack and pinion’ system is added to some trains to overcome this problem. A large gear wheel is added to the centre of the train and an extra track is, with teeth, called a ‘rack’ is added to the track. As the train approaches a steep hill or slope the gear is lowered to the track and it meshes with the ‘rack’. The train does not slip backwards but it is pulled up the steep slope.



Application:-

                  Rack and pinion gears provide a less mechanical advantage than other mechanisms, but greater feedback and steering sensation. A rack and pinion gear gives a positive motion especially compared to the friction drive of a wheel in tarmac. In a rack and pinion railway, a central rack between the two rails engages with a pinion on the engine allowing a train to be pulled up very steep slopes.

                  Rack and pinions gears are commonly used in the steering system of cars to convert the rotary motion of the steering wheel to the side to side motion in the wheels. The steering wheel rotates a gear which engages the rack. As the gear turns, it slides the rack either to the right or left, depending on which way the wheel is turned. Rack and pinion gears are also used in some scales to turn the dial that displays a weight.

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)What is enthalpy?
Ans:-Enthalpy is the heat content of a chemical system.

2.) What is a positive displacement pump?
Ans:-A positive displacement pump causes a liquid or gas to move by trapping a fixed amount of fluid or gas and then forcing (displacing) that trapped volume into the discharge pipe. Positive
displacement pumps can be further classified as either rotary­type (for example the rotary vane)or lobe pumps similar to oil pumps used in car engines. These pumps give a non­pulsating output or displacement unlike the reciprocating pumps. Hence, they are called positive displacement pumps.

3.) Why would you use hydraulics rather than pneumatics?
Ans:-Hydraulics is suitable for higher forces & precise motion than pneumatics. This is because hydraulic systems generally run at significantly higher pressures than pneumatics systems.Movements are more precise (repeatable) because hydraulics uses an incompressible liquid to transfer power whilst pneumatics uses gases.Pneumatic systems have some advantages too. They are usually significantly cheaper than hydraulic systems, can move faster (gas much less viscous than oil) and do not leak oil if they
develop a leak.

MECHANICAL ENGINEERING QUESTIONS

MECHANICAL ENGINEERING QUESTIONS

1.)What is the difference between shear center flexural center of twist and elastic center?
Ans:-The shear center is the centroid of a cross­section. The flexural center is the center of twist, which is the point on a beam that you can add a load without torsion. The elastic center is located at the center of gravity. If the object is homogeneous and symmetrical in both directions of the cross ­section then they are all equivalent.

2.) 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.

3.)What is ductile­ brittle transition temperature?
Ans:-It is the temperature below which the tendency of a material to fracture increases rather than forming. Below this temperature the material loses its ductility. It is also called Nil Ductility Temperature.

4.)What is isometric drawing?
Ans:-It is a 3­D drawing used by draftsmen, architects etc

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)Which conducts heat faster steel copper or brass?
Ans:-Copper conducts heat faster than steel or brass. Any material that is good for conducting heat is also good for electricity in most cases. Wood terrible for transferring heat thus is also insulator for electric.

2.) What is a Process Flow Diagram?
Ans:-A Process Flow Diagram (or System Flow Diagram) shows the relationships between the major components in the system. It also has basic information concerning the material balance for the process.

3.) Where pneumatic system is used?
Ans:-Any system needs redundancy in work needs pneumatics, because the compressor of the pneumatic system has periodical operations (intermittent work, not as hydraulic pump). The compressed air could be accumulated in tanks with high pressures and used even if the compressor failed.

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)Why gas containers are mostly cylindrical in shape?
Ans:-The most efficient shape for withstanding high pressure is a sphere but that would be costly to manufacture. A cylinder with a domed top and a domed bottom (look underneath, the flat base is actually welded around the outside, the bottom of the gas container is actually domed) is a much cheaper shape to manufacture whilst still having good strength to resist the internal gas pressure.

2.) How is martensite structure formed in steel?
Ans:-Martensite transformation begins when austenite is cooled below a certain critical temperature,called the matrensite start temperature. As we go below the martensite start temperature, more and more martensite forms and complete transformation occurs only at a temperature called martensite finish temperature. Formation of martensite requires that the austenite phase must be cooled rapidly.

3.) What is an orthographic drawing?
Ans:-Orthographic projections are views of a 3D object, showing 3 faces of it. The 3 drawings are aligned so that if the page were folded, it would create part of the shape. It is also called multiview projections.The 3 faces of an object consist of its plan view, front view and side view. There are 2 types of orthographic projection, which are 1st angle projection and 3rd angle projection.

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)What does angular momentum mean?
Ans:-Angular momentum is an expression of an objects mass and rotational speed. Momentum is the velocity of an object times it is mass, or how fast something is moving how much it weigh. Therefore, angular momentum is the objects mass times the angular velocity where angular velocity is how fast something is rotating expressed in terms like revolutions per minute or radians per second or degrees per second.

2.)What is the role of nitrogen in welding?
Ans:-Nitrogen is used to prevent porosity in the welding member by preventing oxygen and air from entering the molten metal during the welding process. Other gases are also used for this purpose such as Argon, Helium, Carbon Dioxide, and the gases given off when the flux burns away during SMAW (stick) welding.

3.) What causes white smoke in two stroke locomotive engines?
Ans:-That is the engine running too lean (lack of fuel). This condition will lead to overheating and failure of the engine.

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)How does iron ore turn into steel?
Ans:-To make Steel, Iron Ore is refined into iron and all the carbon is burned away using very high heat (Bessemer). A percentage of Carbon (and other trace elements) are added back to make
steel.

2.)What is knurling?
Ans:-Knurling is a machining process normally carried our on a centre lathe. The act of Knurling creates a raised criss­cross pattern on a smooth round bar that could be used as a handle or
something that requires extra grip.

3.)What is extrued aluminum?
Ans:-Extrusion is the process where a metal or a metal bar is pulled through a mandrel to elongate it and/or give it a final shape.
Extruded Aluminum is a common form of making small aluminum wire, bars or beams and many varieties of small non­structural, decorative pieces.

4.) 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.

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)What are the advantages of gear drive?
Ans:-In general, gear drive is useful for power transmission between two shafts, which are near to each other (at most at 1m distance). In addition, it has maximum efficiency while transmitting power. It is durable compare to other such as belts chain drives etc. You can change the power to speed ratio.

Advantages: ­

• It is used to get various speeds in different load conditions.
• It increases fuel efficiency.
• Increases engine efficiency.
• Need less power input when operated manually.

2.)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.


3.) 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.

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)What is the difference between Production and Manufacturing?
Ans:-Production is an term denoting the activity performed right procuring raw material to finally packing and sending it to the receiver end.
Manufacturing is an term denoting a particular process like machining, shaping etc.

2.)What is the difference between displacement pumps and centrifugal pump?
Ans:-Displacement pump is a device which deliver a constant volume of liquid for each cycle at varying discharge (Q) pressure or HEAD.
Centrifugal pump is a device in which high velocity of the liquid will then produce a velocity head and at the same time producing a high flow rate

3.)What are the rules that must be kept in mind while designing castings?
Ans:-Some of the points that must be kept in mind during the process of cast designing are as follows:

•  To avoid the concentration of stresses sharp corners and frequent use of fillets should be avoided.
•  Section thicknesses should be uniform as much as possible. For variations it must be done gradually.
•  Abrupt changes in the thickness should be avoided at all costs.
•  Simplicity is the key, the casting should be designed as simple as possible.
•  It is difficult to create true large spaces and henceforth large flat surfaces must be avoided.
•  Webs and ribs used for stiffening in castings should as minimal as possible.
•  Curved shapes can be used in order to improve the stress handling of the cast.

Bolt nomenclature

Bolt nomenclature

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)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.

2.) What is the position of Piston Ring?
Ans.In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck.

Types of gear

Types of gear

AUTOMOBILE ENGINEERING INTERVIEW QUESTIONS

AUTOMOBILE ENGINEERING INTERVIEW QUESTIONS

1)The part of an overhead valve mechanism arranged between the valve tappet and rocker arm is known as
Ans: Push rod

2.)In carburetors, compensating devices are used to provide?
Ans: Correct proportions of fuel air mixture at all speeds

3.). Spark plug gap is generally measured by a?
Ans: Feeler gauge

4.). In case of a friction clutch, the pressure plate is held against the clutch plate by?
Ans: Thrust springs

5.) Which transmission unit is used to turn the driven shaft faster than the driving shaft?
Ans: Overdrive

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

MECHANICAL ENGINEERING INTERVIEW QUESTIONS

1.)What are the Advantages and Disadvantages of using LPG in Car?
Ans. Advantages:-

a.) Complete combustion
b.) Fuel saving
c.) Homogenous combustion


Disadvantages:-

a.) As complete combustion is occurring ,more heat liberated,not advised for long journey, engine will be over heated
b.)Installation is difficult
c.)Reduce engine life efficiency


2.)What is the difference between Speed and Economic Speed?
Ans.The rated speed tells us about the maximum speed which can be achieved by a vehicle or some other machine but the economical speed means the speed limit at which the machine works efficiently with least consumption of fuel.eg-in normal bikes(not racing),the max.speed limit shown on speedometer is upto 120 kmph but companies always advice their customers to drive such bikes at around 60 kmph to have maximum mileage.

3.)State all the laws of Thermodynamics?
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 not in 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.

Relationship between the stress and strain

Relationship between the stress and strain

The relationship between the stress and strain that a particular material displays is known as that particular material's stress–strain curve. It is unique for each material and is found by recording the amount of deformation (strain) at distinct intervals of tensile or compressive loading (stress). These curves reveal many of the properties of a material (including data to establish the Modulus of Elasticity, E).

Fixture

Fixture
A fixture is a work-holding or support device used in the manufacturing industry.Fixtures are used to securely locate (position in a specific location or orientation) and support the work, ensuring that all parts produced using the fixture will maintain conformity and interchangeability. Using a fixture improves the economy of production by allowing smooth operation and quick transition from part to part, reducing the requirement for skilled labor by simplifying how workpieces are mounted, and increasing conformity across a production run.

Function car engine parts

Function car engine parts

In this issue we talk about every part of the car engine and we explain all the engine parts auto detailing. Modus operandi of car engine

• Internal combustion engine
• And learned that the internal combustion engine is a key part of the auto engine parts
• And explain the position of these addresses
• Date emergence of an internal combustion engine and its development
• Practical Applications
• How to operate
• Process flammable gasoline
• Ignition diesel

The internal combustion engine is the engine where fuel combustion and oxidized material (usually air) within the limited space called a combustion chamber. This reaction is called exothermic gas at high temperature and pressure, and allows these gases for expansion. The main thing that distinguishes the internal combustion engine is that the job is useful efforts of the expanding hot gases that compress directly to cause movement of engine parts solid, and clicking on the piston or rotor, or even move the entire engine. This contrast of engines

What is Triple Spark Technology

What is Triple Spark Technology

Along with the announcement of the new Pulsar 200NS,came a new technology named Triple Spark technology. Which is being used in the new bike. In simple words, the triple spark technology is nothing but a engine with 3 spark plugs housed in it.

To make use of 3 spark plugs, the pulsar engine houses a pent roof combustion chamber which in turn allows to house 3 spark plugs in the engine chamber. Out of the three plugs, the primary plug is the center one and is mounted in an angle and enters the chamber at the top-center. The other two secondary plugs are mounted below, each opposite each other and one of them being vertically underneath the primary plug.

The secondary plugs fires a bit after the primary one has fired and the timings are controlled by the ECU depending on various parameters like throttle position, engine revs,load on engine and many other stuffs. According to Bajaj, these plugs gain a advantage in low-rev riding condition where it extracts the best economy.Compared to KTM Duke 200 in similar conditions it gives as much as 10-13kmpl more,however the difference vanishes at higher revs and high speed.

Steam turbine

Steam turbine

A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884.
Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator – about 90% of all electricity generation in the United States (1996) is by use of steam turbines.The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency through the use of multiple stages in the expansion of the steam, which results in a closer approach to the most efficient reversible process.

Steam turbines are made in a variety of sizes ranging from small <0.75 kW (1< hp) units (rare) used as mechanical drives for pumps, compressors and other shaft driven equipment, to 1,500,000 kW (2,000,000 hp) turbines used to generate electricity.

OPPOSED PISTON OPPOSED CYLINDER ENGINE

OPPOSED PISTON OPPOSED CYLINDER ENGINE

The basic OPOC engine consists of two cylinders on either side of a crankshaft. Multiple engines, or “modules,” can be used together to boost the fuel efficiency of a vehicle by as much as 45 percent. In addition to the efficiency gains of the engine itself, extra modules can be deactivated when they aren’t needed. Key to the design is an electrically controlled clutch, which disengages a module when necessary. Some modern V8 engines feature cylinder deactivation, but the pistons continue to turn due to their connection to the crankshaft, resulting in what’s known as “parasitic loss

Heat engine

Heat engine

A heat engine is a system that performs the conversion of heat or thermal energy to mechanical work. It does this by bringing a working substance from a lower state temperature to a higher state temperature.

LEGACY ENGINE

LEGACY ENGINE

The Legacy engine is a revolutionary, patented engine that offers significant advances over conventional internal combustion engines in 1) power to weight ratio; 2) multiple fuel acceptance; 3) fuel economy; and 4) environmental compliance. This is achieved through a combination of innovative design geometry, rotary motion, aspiration simplicity, and manufacturing/part simplicity.

The Legacy engine offers tremendous benefits over any existing or development stage engines. And has the potential for significant Global impact from:

Better fuel economy

20% More efficient than ANY conventional engine
Innovative Combustion Geometry Saving the average family $800 per year in fuel expense
Less Pollution

20% less fuel is needed to make the same power
Reduce the amount of carbon emitted by 6 tons per vehicle per year for a long haul tractor trailer.
Alternative Fuels: Can operate on any fuel including biodiesel, natural gas and hydrogen
Small, lightweight, and powerful

1/4th the size and weight of a conventional engine
Nine combustion cycles per rotation of the drive shaft; A single rotor Legacy is equivalent to an 18 cylinder four-stroke engine
Lower Cost

Cost 50% less to manufacture
Only 12 major components
No eccentric or reciprocating motion; less vibration & wear
Simple and adaptable design.

HOW THE POWER(rack and pinion) STEERING WORKS

HOW THE POWER(rack and pinion) STEERING WORKS

Let me explain it to you...

#The components of the power steering consist of:

• Power steering pump

•Power steering fluid

•Speed sensor

•Steering rack

•Steering wheel

The POWER STEERING PUMP is a rotary pump driven by a belt from the main pulley of the engine at roughly twice engine speed. This pump is designed to circulate POWER STEERING FLUID through the SPEED SENSOR and at very high pressure from the pump to the STEERING RACK. STEERING WHEEL movements cause pressurized fluid to be directed one way or the other inside the steering rack.

The steering rack is under the vehicle between the front wheels. The power steering fluid is directed under pressure to the rack. The steering wheel provides input from the driver to the rack, directing power assist when necessary.

Power steering fluid is designed to withstand about 1200 lbs of pressure without breaking down or foaming. Hondas use a special fluid that is a type of whale oil. Do not attempt to use any other type of fluid, as it will foam under pressure and destroy the seals in the rack assembly causing loss of fluid resulting in loss of power assisted steering.

The speed sensor is attached to the transmission and senses vehicle speed. The power steering system is designed to provide maximum assist when the vehicle is traveling slowly. As speed increases, assist pressure decreases. So that at 35 MPH the power steering is providing no assist. The power resumes with reduction of speed.

On vehicles with four wheel steering, the front rack assembly provides power assist to the rear wheels.

A new type of power steering is now available on the Civic hybrid. This steering is based on electricity, not fluid. This means that the power steering is available, even if the engine is not running, such as when the auto off feature is in effect. The electrical power steering has several benefits: Less power from the engine to operate, more precise steering, power steering is available at all times, not to mention less weight.
...and that's the way the power steering works!!

Water engine

Water engine

The water engine is a positive-displacement engine, often closely resembling a steam engine, with similar pistons and valves, that is driven by water pressure. The supply of water was derived from a natural head of water, the water mains, or a specialized high-pressure water supply.

Because water is incompressible, the valve gear of water engines is more complicated than that used in steam engines, and some water engines even had a small secondary engine solely to power the operation of their valves. Closing a valve too quickly can cause very large pressures to result, and pipework to explode (a phenomenon similar to water hammer).

A prerequisite for the correct function of the water engine was sufficient pressure in the water pipes. In times of high water consumption (before or after work) the water pressure was often insufficient. In hard winters, in which the water pipes often froze, the water engine could not be used

Qualities of a good boiler

Qualities of a good boiler

Qualities of a good boiler CAN YOU TELL MORE????

(i) Highest thermal efficiency

(ii) Highest operational safety

(iii) Low emission of carbon monoxide,NOx and SOx in flue gases

(iv) Low free carbon emission (black smoke)in flue gas.

(v) optimum vacuum in economiser.

(vi) Lesser requirement of soot blowing

(vi) Effective heat recovery from flue gas for heating : boiler feed water,primary air to combustion chamber and fuel oil.

(vii) less requirement of blow down

Fluid coupling

Fluid coupling

A fluid coupling is a hydrodynamic device used to transmit rotating mechanical power.It has been used in automobile transmissions as an alternative to a mechanical clutch. It also has widespread application in marine and industrial machine drives, where variable speed operation and/or controlled start-up without shock loading of the power transmission system is essential.

A fluid coupling consists of three components, plus the hydraulic fluid:

>The housing, also known as the shell(which must have an oil tight seal around the drive shafts), contains the fluid and turbines.

>Two turbines (fan like components):

*One connected to the input shaft; known as the pump or impeller, primary wheel input turbine

*The other connected to the output shaft, known as the turbine, output turbine, secondary wheel or runner

The driving turbine, known as the 'pump', (or driving torus) is rotated by the prime mover, which is typically an internal combustion engine or electric motor. The impellor's motion imparts both outwards linear and rotational motion to the fluid.

The hydraulic fluid is directed by the 'pump' whose shape forces the flow in the direction of the 'output turbine' (or driven torus). Here, any difference in the angular velocities of 'input stage' and 'output stage' result in a net force on the 'output turbine' causing a torque; thus causing it to rotate in the same direction as the pump.

Fluid couplings are relatively simple components to produce. For example, the turbines can be aluminum castings or steel stampings, and the housing can also be a casting or made from stamped or forged steel.

The torque capacity of a two pads disk brake

The torque capacity of a two pads disk brake

The torque capacity of a two pads disk brake can be expressed as

T = μ F r (1)

where

T = torque (Nm)

μ = coeficient of friction

F = force on pad (N)

r = mean radius of pad (m)

Required pad pressure can be expressed as

p = F / A (2)

where

p = pressure (Pa)

A = pad area

TOOL MAKER MICROSCOPE

TOOL MAKER MICROSCOPE

These microscopes are special type of microscopes that are used to create precision tools and measure small distances between two points of a specimen.

A tool maker microscope is a type of a multi functional device that is primarily used for measuring tools and apparatus. These microscopes are widely used and commonly seen inside machine and tools manufacturing industries and factories. These microscopes are also inside electronics production houses and in aeronautic parts factories. A tool maker microscope is an indispensable tool in the different measurement tasks performed throughout the engineering industry.

The main use of a tool maker microscope is to measure the shape, size, angle, and the position of the small components that falls under the microscope’s measuring range. More often than not, a tool maker microscope is outfitted with a CCD camera that has the ability to capture, collect, and store images into specialized computer software. Certain computer aided design software is commonly used for such applications. The image produced by the camera and processed by the software is normally a two dimensional image.

Industrial Automation & Robotics

Industrial Automation & Robotics

Machinery Automation and Robotics provides complete automation and robotic solutions to a wide range of companies Australia wide. With extensive experience in the industry, the company here illustrates some of the benefits of adopting industrial robots for businesses of any size.

Technological innovations have made significant progress in making production and distribution easy and efficient. Whether operating a small company or a big business, there are a number of robotic component solutions available for performing a large number of different functions.

Industrial robots can assist in:

Reducing costs
Improve quality
Increasing production
Address Workplace Health & Safety

Turbocharger

Turbocharger

Turbocharger is a gas compressor, purposely used for force induction and increase the car performance. With increase of air density pass through the engine, to create more power for the car.

Engine

Engine

Part

1 Compressor Inlet

2 Compressor Discharge

3 Charge air cooler (CAC)

4 Intake Valve

5 Exhaust Valve

6 Turbine Inlet

7 Turbine Discharge

Ball Bearing

Ball Bearing

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling they have a much lower coefficient of friction than if two flat surfaces were sliding against each other.