Advantages Dual Exhaust Systems Over Single Exhaust Systems:-

Advantages Dual Exhaust Systems Over Single Exhaust Systems:-

1.Engine Power: A dual exhaust system increases engine horsepower by speeding up the rate at which engine combustion gases escape an engine. By allowing engine exhaust gases to exit an engine much quicker than a single exhaust system, a dual exhaust system reduces both engine back-pressure and workload, which reslits in a considerable increase in engine horsepower.

2.Gas Mileage: Speeding up the rate at which exhaust gases escape an engine allows an engine to "breathe" better and turn easier, thereby increasing vehicle gas mileage by eliminating engine strain.

3.Engine Longevity: Vehicles equipped with dual exhaust systems generally have engines that last longer.

4.Engine Efficiency: An engine's overall efficiency is related to how effectively it burns its engine combustion gases and removes them through its exhaust system. Dual exhaust systems, which allow for the rapid escape of burned exhaust gases, promote increased engine combustion and combustion gas removal, both of which lead to an increase in overall engine efficiency.

5.Exhaust Efficiency: Vehicles equipped with dual exhaust systems generally produce more efficient exhaust emissions than do vehicles equipped with single exhaust. Dual exhaust systems allow for more efficient and complete burning of exiting exhaust gases, due in part to the speed at which these gases exit and engine, which leads to an overall increase in exhaust efficiency.

Top 10 Reasons – Why should one be a Mechanical Engineer?

1. You have a great opportunity to create something innovative and useful. Your creation solve
the problem of others and it gives you great feeling.

2.   It is really broad branch of engineering so career options are wide after graduation.

3.   Variety in the learning- you learn how to design the thing from safety pin to aircraft.

4.   Easy to understand the thing whatever you learn.

5.   You create a range of skills- you learn as a machine operator, a smith , a foundry man, a mechanic, a plant manager, a plant manager, a researcher and rule maker.

6.    You work with massive machines to tiny precious instruments , micro and nano devices.

7.   Every industry has a importance of your work because you are only human resources that required for the survival of any industry.

8.   Get paid very handsomely (after gaining little year experience.)

9.   Not much of girls hanging around. You do not have to worry about geeting dressed perfectly for class or for girls.

10.                It sounds and nice feeling to be called as a mechanical engineer.

DIFFERENTIAL

Introduction:-

The differential is an integral part of all four wheeler. Differential technology was invented centuries ago and is considered to be one of the most
ingenious inventions human thinking has ever produced.The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed. 

Why the Differential gear is used?

Wheels receive power from the engine via a drive shaft. The wheels that receive power and make the vehicle move forward are called the drive wheels. The main function of the differential gear is to allow the drive wheels to turn at different rpms while both receiving power from the engine.

The differential has three jobs:

• To aim the engine power at the wheels
• To act as the final gear reduction in the vehicle, slowing the rotational speed of the transmission one final time before it hits the wheels
• To transmit the power to the wheels while allowing them to rotate at different speeds (This is the one that earned the differential its name.)

Parts of differential is shown in figure above :-

Differential Operation:-

Now let’s see how the differential manages to rotate the side gears (drive wheels) at different speeds as demanded by different driving scenarios.

The vehicle moves straight

In this case, the spider gear rotates along with the ring gear but does not rotate on its own axis. So the spider gear will push and make both the side gears turn, and both will turn at the same speed. In short, when the vehicle moves straight, the spider-side gear assembly will move as a single solid unit.

The vehicle takes a right turn

Now consider the case when the vehicle is taking a right turn. The spider gear plays a pivotal role in this case. Along with the rotation of the ring gear it rotates on its own axis. So, the spider gear is has a combined rotation. The effect of the combined rotation on the side gear is interesting.When properly meshed, the side gear has to have the same peripheral velocity as the spider gear. Technically speaking, both gears should have the same pitch line velocity. When the spider gear is spinning as well as rotating, peripheral velocity on the left side of spider gear is the sum of the spinning and rotational velocities. But on the right side, it is the difference of the two, since the spin velocity is in the opposite direction on this side.This means the left side gear will have higher speed compared to the right side gear. This is the way the differential manages to turn left and right wheels at different speeds.

The vehicle takes a left turn

While taking a left turn, the right wheel should rotate at a higher speed. By comparing with the previous case, it is clear that, if the spider gear spins in the opposite direction, the right side gear will have a higher speed.

DIFFERENT TYPES OF LAYOUT IN AUTOMOBILES

1.)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.

2.)Rear engine rear wheel drive

Rear-engine, Rear-wheel-drive layout places both the engine and drive wheels at the rear of the vehicle.It is shown in figure below

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.

3.)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.

ALL ABOUT GEARS

Gears are toothed wheels which are used to transmit force to other gears or toothed parts by meshing with minimal slip.
When two gears are meshed together, the smaller gear is called a pinion. The gear transmitting force is referred to as a drive gear, and the receiving gear is called the driven gear.

When pinion is the driver, it results in step down drive in which the output speed decreases and the torque increases. On the other hand, when the gear is the driver, it results in step up drive in which the output speed increases and the torque decreases.

Law of gearing:-

The angular velocity ratio of all gears of a meshed gear system must remain constant also the common normal at the point of contact must pass through the pitch point.

Screw thread terminology

Powder metallurgy

Powder metallurgy:-

Powder metallurgy is the process of blending fine powdered materials, pressing them into a desired shape or form (compacting), and then heating the compressed material in a controlled atmosphere to bond the material (sintering). The powder metallurgy process generally consists of four basic steps: powder manufacture, powder blending, compacting, and sintering. Compacting is generally performed at room temperature, and the elevated-temperature process of sintering is usually conducted at atmospheric pressure. Optional secondary processing often follows to obtain special properties or enhanced precision. The use of powder metal technology bypasses the need to manufacture the resulting products by metal removal processes, thereby reducing costs.

Powder metallurgy is also used in "3D printing" of metals.

CHOKE IN BIKES

Choke valve in bikes :-

A choke valve is sometimes installed in the carburetor of internal combustion engines. Its purpose is to restrict the flow of air, thereby enriching the fuel-air mixture while starting the engine. Depending on engine design and application, the valve can be activated manually by the operator of the engine (via a lever or pull handle) or automatically by a temperature-sensitive mechanism called an autochoke.

Why it is important?

Choke valves are important for naturally aspirated gasoline engines because small droplets of gasoline do not evaporate well within a cold engine. By restricting the flow of air into the throat of the carburetor, the choke valve reduces the pressure inside the throat, which causes a proportionally greater amount of fuel to be pushed from the main jet into the combustion chamber during cold-running operation. Once the engine is warm (from combustion), opening the choke valve restores the carburetor to normal operation, supplying fuel and air in the correct stoichiometric ratio for clean, efficient combustion.

A 9,000-Pound Tank That’s Faster Than a Ferrari

A 9,000-Pound Tank That’s Faster Than a Ferrari :-

After drones took over the skies, Ripsaw is now taking control over land. Ripsaw is the world’s fastest tracked vehicle produced by Howe & Howe Technologies in Maine. Unlike other unmanned ground vehicles (UGV), which are slow, Ripsaw can accelerate to 65 mph in about 3 seconds. By comparison, the Ferrari F12 Berlinetta can accelerate to 62 mph in 3.1 seconds.

Ripsaw, made from tough alloy steel, is very quick and agile and could be used for perimeter defense, surveillance, rescue, border patrol, crowd control and explosive ordnance disposal roles. 

RESISTANCE SPOT WELDING

Resistance Spot Welding:

In spot welding the weld is effected by the heat produced due to resistance to the flow of current through two or more overlapping work pieces held pressed together between the electrodes. This is the simplest form of resistance welding and does not pose any problem for welding sheets ranging u to 12.5 mm in thickness. The majority of spot welding is however done with metal pieces less than 6 mm thick.

HONING

Honing:-

Honing or to "Hone"is an abrasive machining process that produces a precision surface on a metal workpiece by scrubbing an abrasive stone against it along a controlled path. Honing is primarily used to improve the geometric form of a surface, but may also improve the surface texture.

Typical applications are the finishing of cylinders for internal combustion engines, air bearing spindles and gears. There are many types of hones but all consist of one or more abrasive stones that are held under pressure against the surface they are working on.

COMPUTATIONAL FLUID DYNAMICS (CFD)

Computational fluid dynamics:-

Computational fluid dynamics, usually abbreviated as CFD, is a branch of fluid mechanics that uses numerical analysis and algorithms to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with surfaces defined by boundary conditions. With high-speed supercomputers, better solutions can be achieved. Ongoing research yields software that improves the accuracy and speed of complex simulation scenarios such as transonic or turbulent flows. Initial experimental validation of such software is performed using a wind tunnel with the final validation coming in full-scale testing, e.g. flight tests.

DIFFERENCE BETWEEN IMPULSE AND REACTION TURBINE

Difference Between Impulse And Reaction Turbine. 

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

FRICTION WELDING

Friction welding:-

Friction welding (FRW) is a solid-state welding process that generates heat through mechanical friction between workpieces in relative motion to one another, with the addition of a lateral force called "upset" to plastically displace and fuse the materials. Technically, because no melt occurs, friction welding is not actually a welding process in the traditional sense, but a forging technique.

TYPES OF BELT DRIVES

Types of Belt Drives:-

Belt drives are widely used in many industries for power transmission since they are cheap and easy to maintain.

The most common types of belt drives include:

Round belts:-
Round belts are are generally made of rubber. This type of belt is generally used for light loads, such as in a sewing machine or a vacuum cleaner.

V belts:-
V belts are arguably the most widely used belts in industry. V belts have a V shaped cross-section, which rests against the side of V pulley under tension. The V shaped cross-section prevents belt from slipping off.

Flat belts:-
Flat belts are also used to transmit power from one shaft to another. They are generally classified as either small woven endless belts or higher power flat belts. The woven endless belts are especially useful where minimum vibration is required at the driven pulley due to semi-elastic material used in construction. The higher power flat belts are often useful because they eliminate the need to high belt tension used to grip pulleys, which in turn reduces the load on the shaft bearings. The material used for high power flat belts is sticky yet abrasion-resistant rubber compounds.

Timing/toothed belts:-
Timing belts are toothed belts that use their teeth for power transmission, as opposed to friction. This configuration results in no slippage, and therefore, the driving and driven shafts remain synchronized. It’s more expensive to manufacture due to complexity of the belt and pulley shapes.

Exhaust gas recirculation

Exhaust gas recirculation:-

In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline and diesel engines. In many countries around the world, the emissions of NOx from diesel and gasoline vehicles are restricted by legislation. NOx is formed in the combustion chamber of engines, when high temperatures cause oxygen and nitrogen (both found in the air supplied for combustion) to combine.EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. Exhaust gas is routed back into the combustion chamber because the exhausted air is much hotter than the intake air. EGR works by diluting the N2 and providing gases inert to combustion (CO2 primarily) to act as an absorbent of combustion heat to reduce peak in-cylinder temperatures. NOx is produced in a narrow band of high cylinder temperatures and pressures.

Gas Welding

Gas Welding

Although the oxyacetylene process has been introduced long time ago it is still applied for its flexibility and mobility. Equipment for oxyacetylene welding consists of just a few elements, the energy necessary for welding can be transported in cylinders.Process energy is obtained from the exothermal chemical reaction between oxygen and a combustible gas, . Suitable combustible gases are C2H2, lighting gas, H2, C3H8 and natural gas; here C3H8 has the highest calorific value. The highest flame intensity from point of view of calorific value and flame propagation speed is, however, obtained with C2H2. C2H2 is produced in acetylene gas generators by the exothermal transformation of calcium carbide with water, Carbide is obtained from the reaction of lime and car- bon in the arc furnace.C2H2 tends to decompose already at a pressure of 0.2 MPa. Nonetheless, commercial quantities can be stored when C2H2 is dis- solved in acetone.

Acetone disintegrates at a pressure of more than 1.8 MPa, i.e., with a filling pressure of 1.5 MPa the storage of 6m3 of C2H2 is possible in a standard cylinder (40 l). For gas ex- change (storage and drawing of quantities up to 700 l/h) a larger surface is necessary, therefore the gas cylinders are filled with a porous mass (diatomite). Gas consumption during welding can be observed from the weight reduction of the gas cylinder.

ANTILOCK BRAKING SYSTEM

ABS is an abbreviation for Anti-lock Braking System. The ABS is a system that prevents wheel lock-up by automatically modulating the brake pressure during an emergency stop. By preventing the wheels from locking, it enables the driver to maintain steering control and to stop in the shortest possible distance under most conditions. It was designed to help the driver maintain some steering ability and avoid skidding while braking.ABS allows you to maintain control of the vehicle. Since four-wheel ABS prevents all wheels from skidding, it allows you to steer the vehicle and still maintain braking.

How does it work?

ABS uses wheel speed sensors to determine if one or more wheels are trying to lock up during braking. If a wheel tries to lock up, a series of hydraulic valves limit or reduce the braking on that wheel. This prevents skidding and allows you to maintain steering control.

In a recent Canadian Automobile Association survey of some 1700 members, 66% correctly associated ABS with vehicle stability in an emergency, and 53% correctly stated that ABS allows the driver to steer while braking.

Since the ABS will not allow the tire to stop rotating, you can brake and steer at the same time. The braking and steering ability of the vehicle is limited by the amount of traction the tire can generate.

If you demand steering while braking, the 100% of traction that the tire can generate will be divided between both tasks. For example, if you require 50% for steering then there is 50% of available traction left for braking. If you require 10% for steering then there is 90% left for braking. Be aware that 100% traction on a dry road is a great deal more traction than 100% traction on ice! Therefore, your vehicle is unable to steer and brake as well on a slippery surface as it can on a dry road.

Crankshaft:-

A crankshaft is a mechanical part able to perform a conversion between reciprocating motion and rotational motion. In a reciprocating engine, it translates reciprocating motion of the piston into rotational motion; whereas in areciprocating compressor, it converts the rotational motion into reciprocating motion. In order to do the conversion between two motions, 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.

It is typically connected to a flywheel to reduce the pulsation characteristic of the four-stroke cycle, and sometimes a torsional or vibrational damper at the opposite end, to reduce the torsional vibrations often caused along the length of the crankshaft by the cylinders farthest from the output end acting on the torsional elasticity of the metal.

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.

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.

REGENERATIVE BRAKING SYSTEM

Every time we step on our car's brakes, we are wasting energy.So when your car slows down, the kinetic energy that was propelling it forward has to go somewhere. Most of it simply dissipates as heat and becomes useless. That energy, which could have been used to do work, is essentially wasted.

Regenerative braking is used on automobiles to recoup some of the energy that is lost while the vehicle is stopping. This technology is used on hybrid vehicles that use both gas and electricity as sources of power. The energy that is recouped during braking is saved in a storage battery and used later to power the motor whenever the vehicle is using its electric power source.Hybrids and all-electric vehicles create their own power for battery recharging through a process known as regenerative braking (regen mode).Simply it means means capturing the vehicle's momentum (kinetic energy) and turning it into electricity that recharges (regenerates) the onboard battery as the vehicle is slowing down and/or stopping. It is this charged battery that in turn powers the vehicle's electric traction motor.

At present, these kinds of brakes are primarily found in hybrid vehicles like the Toyota Prius, and in fully electric cars, like the Tesla Roadster.However, the technology was first used in trolley cars and has subsequently found its way into such unlikely places as electric bicycles and even Formula One race cars.

How does it work?

In braking systems on conventional vehicles, friction is used to counteract the forward momentum of a moving vehicle.This friction is what turns the car's kinetic energy into heat. With regenerative brakes, on the other hand, the system that drives the vehicle does the majority of the braking. It uses completely different method of braking at slower speeds. Hybrid vehicles still use conventional brake pads at highway speeds, but electric motors help the vehicle brake during stop-and-go driving at slower speeds. As the driver applies the brakes by pressing down on a conventional brake pedal, the electric motors reverse direction. The torque created by this reversal counteracts the forward momentum and eventually stops the car.In simple words,when the driver steps on the brake pedal of an electric or hybrid vehicle, these types of brakes put the vehicle's electric motor into reverse mode, causing it to run backwards, thus slowing the car's wheels. While running backwards, the motor also acts as an electric generator, producing electricity that's then fed into the vehicle's batteries.

Advantages of regenerative braking system:-

>Increase of overall energy efficiency of a vehicle.

>—Increases vehicle range.

>—Cuts down on pollution related to electricity generation.

>Increases the lifespan of friction braking systems.

>—Less use of traditional mechanical brakes leads to less wear over time.