CRDI (Common Rail Direct Injection)

          CRDi stands for Common Rail Direct Injection meaning, direct injection of the fuel into the cylinders of a diesel engine via a single, common line, called the common rail which is connected to all the fuel injectors.
                                           

          Whereas ordinary diesel direct fuel-injection systems have to build up pressure anew for each and every injection cycle, the new common rail (line) engines maintain constant pressure regardless of the injection sequence.

Advantages & Disadvantages

Advantages:-

          CRDi engines are advantageous in many ways. Cars fitted with this new engine technology are believed to deliver 25% more power and torque than the normal direct injection engine. It also offers superior pick up, lower levels of noise and vibration, higher mileage, lower emissions, lower fuel consumption, and improved performance.

          In India, diesel is cheaper than petrol and this fact adds to the credibility of the common rail direct injection system.

Disadvantages:-

          Like all good things have a negative side, this engine also have few disadvantages. The key disadvantage of the CRDi engine is that it is costly than the conventional engine. The list also includes high degree of engine maintenance and costly spare parts. Also this technology can’t be employed to ordinary engines.

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FEW MEANINGS OF MECHANICAL BASED TERMS

ACCURATE – Without error within tolerances allowed, precise, correct, confirming exactly to standard.

ACME THREAD – A screw thread having an included angle of 29° and largely used for feed screws on machine tools.

ACUTE ANGLE – An angle which is less than a right angle, 90°.

ADDENDUM – The portion of the tooth of a gear that extends from the pitch line to the outside.

ALIGN – To bring two or more components of a unit into correct positions with respect to one another.

ALLOWANCE – The intentional or desired difference between the maximum limits of mating parts to provide a certain class of fit.

ANGLE – The amount of opening or divergence between two straight lines that meet at a vertex or that intersect each other.

ANGLE OF THREAD – The included angle between the sides forming the groove of the screw thread.

ANNULUS – A figure bounded by concentric circles or cylinders (e.g.,a washer, ring, sleeve etc.).

ARC – A circular section of the circumference of a circle bounded by two equal radii.

ASSEMBLY – A unit that contains the parts that make up a mechanism or a machine.

AXIS – The line real or imaginary, which passes through the center of a body and about which the body would rotate if set revolving.

BACKLASH - The clearance or amount of movement between the tooth profiles of a pair or train of gears in mesh. Also refers to the looseness or lost motion between screw threads which have been badly worn.

BAFFLE - A device which slows down or diverts the flow of gases, liquid, sound etc.

BASIC SIZE - The theoretical or nominal standard size from which all variations are made.

BASTARD - Not standard, irregular. A bastard cut file is a rough cut file having coarse teeth than a second cut file.

BELL MOUTHED HOLE - A hole which is rounded or tapered slightly larger at one end or both ends and is not exactly cylindrical throughout its entire length.

BEVEL - Any surface not at right angle to the rest of the workpiece. If a bevel is at a 45° angle, it is frequently called a MITER.

BIMETALLIC STRIP - A strip of metal consisting of one metal (or alloy) in the top portion bonded to a different metal in the bottom portion.A straight strip becomes curved when heated.

BLIND HOLE - A hole which is made to a certain depth of a workpiece but does not pass through it.

BISECTING AN ANGLE - Dividing an angle into two equal parts.

BOND - The holding together of different parts.

BORE - The inside diameter of a cylinder, or a hole for a shaft. Also the operation of machining a circular hole in a metal workpiece.

BRUSH - Pieces of carbon or copper that make a sliding contact against the commutator or slip rings.

CAM - A plate or cylinder which transmits variable motion to a part of a machine by means of a follower.

CAP SCREW - A finished screw 5mm or larger, used for fastening two pieces together by passing the screw through a clearance hole in one part and screwing in into a tapped hole in the other.

CENTER - A fixed point about which the radius of a circle or an arc moves.

CENTER LINE - A line used on drawings to show the centers of objects and holes. The center line consists of alternate long and short dashes.

CHAMFER – To bevel or remove the sharp edge of a machined part.

CHECK VALVE – A valve which permits flow in one direction only.

CIRCULAR PITCH – The distance from the center of one gear tooth to the center of the next gear tooth measured on the pitch line.

CIRCUMFERENCE – A curved line forming a circle and the length of this line.

COIL SPRING – A spring steel wire wound in a spiral pattern.

COMMUTATOR – A number of copper bars connected to the armature windings but insulated from each other and from the armature.

CONVOLUTION – One full turn of screw.

CORE – The central or innermost part of an object.

COUNTER BORING – The operation of enlarging a portion of a hole for part of its depth and to a given diameter, as for the head of a fillister head screw.

COUNTER SINK – To cut or shape a depression in an object so that the head of a screw may set flush or below the surface.

CREST CLEARANCE – Defined on a screw form as the space between the top of a thread and the root of its mating thread.

CREST OF SCREW THREAD – The top surface joining the two sides of flanks of a thread.

CROWNED – A slight curve in a surface e.g., on a roller or race way.

DEDENDUM – The depth of a gear tooth space below the pitch line or circle. Also, the radial distance between the pitch circle and the root circle, which also includes the clearance.

DIAPHRAGM – A flexible dividing partition separating two compartments.

DOUBLE FLARE – A flared end of the tubing having two wall thickness.

DOWEL – A pin, usually of circular shape like a cylinder, used to pin or fasten something in position temporarily or permanently.

DRIFT PIN – A round tapered steel pin used to align rivet holes so that the rivet will pass through the holes easily.

ECCENTRIC – A circle or cylinder having a different center from another coinciding circle or cylinder. Also, a device for converting rotary motion to reciprocating motion.

END PLAY – As applied to a shaft, the amount that the shaft can move backward and forward.

EYE BOLT – A bolt threaded at one end and bent to a loop at the other end.

FEATHER – A sliding key, sometimes called splint. Used to prevent a pulley, gear or other part from turning on a shaft but allows it to move lengthwise. The feather is usually fastened to the sliding piece.

FILLET – A concave surface connecting the two surfaces meeting at an angle.

FLANGE– A metal part which is spread out like a rim, the action of working a piece or part to spread out.

FLANK (Side of thread) – The straight part of the thread which connects the crest with the root.

FLARE – To open or spread outwardly.

FULCRUM – The pivot point of a lever.

FLUSH – When the surfaces of different parts are on the same level, they are said to be flush.

FLUTE – A straight or helical groove of angular or radial form machined in a cutting tool to provide cutting edges and to permit chips to escape and the cutting fluid to reach the cutting edges.

GATE VALVE – A common type of manually operated valve in which a sliding gate is used to obstruct the flow of fluid.

GEAR – A general term applied to types of toothed wheels, valve motion, pump works, lifting tackle and ropes.

GEARING – A train of gears or an arrangement of gears for transmitting motion in a machinery.

GIB – An angular or wedge like strip of metal placed between two machine parts, usually sliding bearings, to ensure a proper fit and provide adjustment for wear.

GLAND – A device to prevent the leakage of gas or liquid past a joint.

HAND WHEEL – Any of the various wheels found on machine tools for moving or positioning parts of the machine by hand feed, as the tail stock hand wheel on a lathe.

HALF MOON KEY – A fastening device in a shape somewhat similar to a semicircle.

HELICAL GEAR – A gear in which the teeth are cut at some angle other than a right angle across the gear face.

HELICOIL – A thread insert used to repair worn or damaged threads. It is installed in a retapped hole to bring the screw thread down to original size.

HELIX – The curve formed by a line drawn or wrapped around a cylinder which advances uniformly along the axis for each revolution, as the thread on a screw or the flute on a twist drill. A helix is often called a
spiral in the shop.

HELIX ANGLE OF A THREAD – The angle made by the helix of the thread at the pitch diameter line with a line at right angle to the axis.

HEXAGONAL NUT – A nut having six sides and shaped like a hexagon.

INVOLUTE GEAR TOOTH – A curved tooth generated by unwinding a string from a cylinder to form the curve.

JOURNAL – The part of a shaft or axle that has been machined or finished to fit into a bearing.

KEYS – Metal pieces of various designs that fit into a slot in a shaft and project above the shaft to fit into a mating slot in the center hole of a gear or pulley to provide a positive drive between the shaft and the gear
or pulley.

KEY-SEAT– The slot or recessed groove either in the shaft or gear, which is made to receive the key. Also, it is called a KEYWAY.

KNURL – A uniform roughened or checked surface of either a diamond, a straight or other pattern.

LAND – The top surface of a tooth of cutting tools, such as taps, reamers and milling cutters.

LEAD ANGLE – The angle of the helix of a screw thread or worm thread. It is the measure of the inclination of a screw thread from a plane perpendicular to the axis of the screw.

LEAD HOLE – A small hole drilled in a workpiece to reduce the feed pressure, aid in obtaining greater accuracy, and guide a large drill. Sometimes called PILOT HOLE.

LEAD OF THREAD – On a single threaded screw, the distance the screw or nut advances in one complete revolution.

LEFT HAND SCREW – One that screws into the mating part or advances when turned to the left or counter clockwise.

LIMITS OF SIZE – The minimum and maximum sizes permissible for specific dimensions.

LINE – A tube, pipe or hose which is used as a conductor of fluid.

LINKAGE – A movable connection between two units.

LOBE – The projecting part such as rotor lobe or the cam lobe.

LOCK NUT – A type of nut that is prevented from loosening under vibration. The locking action is accomplished by squeezing, gripping or jamming
against the bolt threads.

LOOSE PULLEY – A pulley which turns freely on a shaft so that a belt can be shifted from the driving pulley to the loose pulley in order to stop a machine driven by an overhead belt drive.

MAJOR DIAMETER – On a straight thread, the diameter of the imaginary cylinder that just touches the crest of an external thread or the root of an internal thread.

MALE PART – The external part of any workpiece which fits into a hole, slot or groove of the mating part.

MANUAL VALVE – A valve which is opened or closed or adjusted by hand.

MESH – Engaging one part with another, as the teeth of one gear mesh with the teeth of a mating gear.

MICRON – One millionth of a meter or 0.039370 inch.

MINOR DIAMETER – On a straight thread, the diameter of the imaginary cylinder which just touches the root of an external thread or the crest of an internal thread.

MORSE TAPER – A self holding, standard taper largely used on drilling tools, drilling machine spindles, and some lathes.

MULTIPLE THREADED SCREW – A screw with two or more threads cut around the periphery of the workpiece to provide an increased lead with a specified pitch.

NUT – A metal fastener of square, hexagon or other shape, having an internal thread which screws onto a bolt, stud or arbor.

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 on-board 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.

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.

Transmission

A machine consists of a power source and a power transmission system, which provides controlled application of the power. Often transmission refers simply to the gearbox that uses gears and gear trains to provide speed and torque conversions from a rotating power source to another device.

Often, a transmission has multiple gear ratios (or simply "gears"), with the ability to switch between them as speed varies. This switching may be done manually (by the operator), or automatically. Directional (forward and reverse) control may also be provided. Single-ratio transmissions also exist, which simply change the speed and torque (and sometimes direction) of motor output.

Backlash

Definition: The amount by which a tooth space exceeds the thickness of an engaging tooth. It can be defined as "the maximum distance or angle through which any part of a mechanical system may be moved in one direction without applying appreciable force or motion to the next part in mechanical sequence"

Depending on the application, backlash may or may not be desirable. It is unavoidable for nearly all reversing mechanical couplings, although its effects can be negated or compensated for. In many applications, the theoretical ideal would be zero backlash, but in actual practice some backlash must be allowed to prevent jamming. Reasons for the presence of backlash include allowing for lubrication, manufacturing errors, deflection under load, and thermal expansion.

Exhaust system

An exhaust system is usually piping used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall system design, the exhaust gas may flow through one or more of:

Cylinder head and exhaust manifold
A turbocharger to increase engine power.
A catalytic converter to reduce air pollution.
A muffler (North America) / silencer (Europe/India), to reduce noise.

Cooling tower

A cooling tower is a heat rejection device which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature.

Micrometer

Micrometer

They enable very accurate measurements to be taken.

Outside micrometers are used to measure:

• Outside diameters

• Thickness of material

• Lengths of parts.

They are available in various sized frames. All sizes,however, have a measuring range limited to the length of

the thread on the spindle.The range is 0 to 25 millimetres.

The principal parts of a micrometer are:

Frame

Anvils

Spindle and Thread

Sleeve or Barrel

Thimble.

A knurled collar or a small lever on the frame can be used to lock the spindle in the barrel. After the anvils have been set against the work being measured, tighten the spindle lock. This prevents any movement of the spindle while you are reading the micrometer scale. Remember to loosen the clamp before attempting to take any further readings.

Principles of a micrometer:

The principle of a micrometer that reads to 0.01 of a millimetre is explained below. Hold a 0‑25 mm outside micrometer by the frame between thumb and first finger of your left hand. Keep the graduations on the sleeve towards you.Loosen the spindle lock. Use the finger and thumb of your right hand on the knurled part of the thimble to screw it anti‑clockwise. This moves the spindle to the right and uncovers the graduations on the sleeve. Look at the gap between the anvils. It is equal to the uncovered 'length of the datum line. Look at the datum line on the sleeve. It is graduated into millimetres and half millimetres, from zero up to 25 mm, and each fifth millimetre is numbered. Turn the thimble until zero is level with the datum line Note the position of the graduation on the sleeve. Turn the thimble one complete turn. The thimble will move along one graduation of the sleeve scale. This is because the pitch of the thread on the spindle is half a millimetre. Two turns of the thimble move the spindle one millimetre. Look at the graduations around the thimble There are 50 graduations and each fifth graduation is numbered Now wipe the face of the anvils with a piece of clean cloth.Screw the thimble inwards towards the frame until the

Diesel Mechanical Locomotive

A diesel-mechanical locomotive is the simplest type of diesel locomotive. As the name suggests, a mechanical transmission on a diesel locomotive consists a direct mechanical link between the diesel engine and the wheels. In the example below, the diesel engine is in the 350-500 hp range and the transmission is similar to that of an automobile with a four speed gearbox. Most of the parts are similar to the diesel-electric locomotive but there are some variations in design mentioned below.

W12 engine

Identification

A W12 engine is a motor with 12 pistons and cylinders configured on the block to form a "W" shape. Some engines contain four banks of three cylinders, while others have three banks containing four cylinders. A single crankshaft operates the pistons. They are common in high-performance and luxury model vehicles such as those from Bentley, Audi, Spyker and Volkswagen.

Design

A W12 engine, simply speaking, is two V6 engines merged into a single unit with 12 uniquely placed cylinders. Each cylinder banks slightly offsets (60 degrees common) the other. Almost all W12 motors have two exhaust systems, one for each block of cylinders.

Benefits

While a W12 engine operates relatively the same as V-type motors, they are more compact and more efficient. Most W12s are known for their sound structures and significantly reduced vibration levels. They are capable of producing a high amount of power while simultaneously running very smoothly. Some W12 engines also have optimum valve placement, with valves placed on the top of their combustion chambers. This adds to compactability and surprising fuel efficiency.

Friction welding

Friction welding (FRW) is a class of solid-state welding processes that generates heat through mechanical friction between a moving workpiece and a stationary component, 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. However, due to the similarities between these techniques and traditional welding, the term has become common. Friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications.

Laser beam welding (LBW)

Is a welding technique used to join multiple pieces of metal through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume applications, such as in the automotive industry.The two types of lasers commonly used are solid-state lasers and gas lasers (especially ruby lasers and Nd:YAG lasers).The first type uses one of several solid media, including synthetic ruby and chromium in aluminum oxide, neodymium in glass (Nd:glass), and the most common type, crystal composed of yttrium aluminum garnet doped with neodymium (Nd:YAG).Gas lasers use mixtures of gases like helium, nitrogen, and carbon dioxide (CO2 laser) as a medium.

Regardless of type, however, when the medium is excited, it emits photons and forms the laser beam Is a welding technique used to join multiple pieces of metal through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume applications, such as in the automotive industry.The two types of lasers commonly used are solid-state lasers and gas lasers (especially ruby lasers and Nd:YAG lasers).The first type uses one of several solid media, including synthetic ruby and chromium in aluminum oxide, neodymium in glass (Nd:glass), and the most common type, crystal composed of yttrium aluminum garnet doped with neodymium (Nd:YAG).Gas lasers use mixtures of gases like helium, nitrogen, and carbon dioxide (CO2 laser) as a medium.

Regardless of type, however, when the medium is excited, it emits photons and forms the laser beam 

Valve

In developed nations we use valves in our daily lives, the most noticeable are plumbing valves, such as taps for tap water. Other familiar examples include gas control valves on cookers, small valves fitted to washing machines and dishwashers, safety devices fitted to hot water systems, and poppet valves in car engines. VALVE is not only a flow controlling device,It also regulates the flow,regulates and controls the pressure.

Check Valve

Check Valve

A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid (liquid or gas) to flow through it in only one direction.

Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. There are various types of check valves used in a wide variety of applications. Check valves are often part of common household items. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, and/or inexpensive. Check valves work automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem. The bodies (external shells) of most check valves are made of plastic or metal.

Hydraulic Accumulator

Hydraulic Accumulator

A hydraulic accumulator is a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure by an external source. The external source can be a spring, a raised weight, or a compressed gas. An accumulator enables a hydraulic system to cope with extremes of demand using a less powerful pump, to respond more quickly to a temporary demand, and to smooth out pulsations. It is a type of energy storage device.

Working Principle

When machine is not working then fluid from the inlet is getting in through pump but not getting out as machine is not working.So it gets stored in an accumulator now as the machine starts working the pressure of fluid from the accumulator plus fluid from pump tries to do the work as a result machine starting effort is reduced.

Advantages

>Stores energy

>Absorbs pulsation

>Acts as shock absorber

>Maintains pressure

>When pump stops working then it acts as support to continue work 

Hydraulic ram

Hydraulic ram

A hydraulic ram, or hydram, is a cyclic water pump powered by hydropower. It takes in water at one "hydraulic head" (pressure) and flow rate, and outputs water at a higher hydraulic head and lower flow rate. The device uses the water hammer effect to develop pressure that allows a portion of the input water that powers the pump to be lifted to a point higher than where the water originally started. The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power other than the kinetic energy of flowing water.

Working

A simplified hydraulic ram is shown in Figure. Initially, the waste valve is open, and the delivery valve is closed. The water in the drive pipe starts to flow under the force of gravity and picks up speed and kinetic energy until the increasing drag force closes the waste valve. The momentum of the water flow in the supply pipe against the now closed waste valve causes a water hammer that raises the pressure in the pump, opens the delivery valve, and forces some water to flow into the delivery pipe . Because this water is being forced uphill through the delivery pipe farther than it is falling downhill from the source, the flow slows; when the flow reverses, the delivery check valve closes. Meanwhile, the water hammer from the closing of the waste valve also produces a pressure pulse which propagates back up the supply pipe to the source where it converts to a suction pulse that propagates back down the pipe. This suction pulse pulls the waste valve back open and allows the process to begin again.

Through this process water can be lifted 10 times the initial height but the initial height should be at least 3 m high.

CAMSHAFT

Basic function of a camshaft is to enable valves open and close. It is a cylindrical part which lays along the cylinders and which has asymmetrical parts; that are placed one for each valve. These asymmetrical parts contacts valve either directly or indirectly through a mechanism as far as the camshaft rotates and opens and closes the valve.

Working of four stroke engine

                                         

The four stroke engine was first demonstrated by Nikolaus Otto in 1876, hence it is also known as the Otto cycle. The technically correct term is actually four stroke cycle. The four stroke engine

is probably the most common engine type nowadays. It powers almost all cars and trucks. The four strokes of the cycle are intake, compression, power, and exhaust. Each corresponds to one full stroke of the piston; therefore, the complete cycle requires two revolutions of the crankshaft to complete.

Fuel injection

Fuel injection

Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive engines, having replaced carburetors during the 1980s and 1990s. A variety of injection systems have existed since the earliest usage of the internal combustion engine.

The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure, while a carburetor relies on suction created by intake air accelerated through a Venturi tube to draw the fuel into the airstream.