A traction engine

A traction engine is a self-propelled steam engine used to move heavy loads on roads, plough ground or to provide power at a chosen location. The name derives from the Latintractus, meaning 'drawn', since the prime function of any traction engine is to draw a load behind it. They are sometimes called road locomotives to distinguish them from railwaylocomotives – that is, steam engines that run on rails.

Traction engines tend to be large, robust and powerful, but heavy, slow, and have poor manoeuvrability. Nevertheless, they revolutionized agriculture and road haulage at a time when the only alternative prime mover was the draught horse.

They became popular in industrialised countries from around 1850, when the first self-propelled portable steam engines for agricultural use were developed. Production continued well into the early part of the 20th century, when competition from internal combustion engine–powered tractors saw them fall out of favour, although some continued in commercial use in the UK into the 1950s and later. All types of traction engines have now been superseded, in commercial use. However, several thousand examples have been preserved worldwide, many in working order. Steam fairs are held throughout the year in the UK, and in other countries, where visitors can experience working traction engines at close hand.

Traction engines were cumbersome and ill-suited to crossing soft or heavy ground, so their agricultural use was usually either "on the belt" – powering farm machinery by means of a continuous leather belt driven by the flywheel – or in pairs, dragging an implement on a cable from one side of a field to another. However, where soil conditions permitted, direct hauling of implements ("off the drawbar") was preferred – in the US, this led to the divergent development of the steam tractor.

Fluid bearings

Fluid bearings are bearings that support their loads solely on a thin layer of liquid or gas.

They can be broadly classified into two types: fluid dynamic bearings and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and the pressurization is done by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces.

Fluid bearings are frequently used in high load, high speed or high precision applications where ordinary ball bearings would have short life or cause high noise and vibration. They are also used increasingly to reduce cost. For example, hard disk drive motor fluid bearings are both quieter and cheaper than the ball bearings they replace.

Needle roller bearing

 A needle roller bearing is a bearing which uses small cylindrical rollers.The difference of a needle roller bearing and roller bearing is the ratio of diameter and length of their rollers, when the ratio of the diameter and the length of roller of a roller bearing is between the interval of 0.4 to 0.1, that roller bearing is called as needle roller bearing. They are used to reduce friction of a rotating surface.

Needle bearings have a large surface area that is in contact with the bearing outer surfaces compared to ball bearings. Additionally there is less added clearance (difference between the diameter of the shaft and the diameter of the bearing) so they are much more compact. The typical structure consists of a needle cage which orients and contains the needle rollers, the needle rollers themselves, and an outer race (sometimes the housing itself).

Radial needle bearings are cylindrical and use rollers parallel to the axis of the shaft. Thrust needle bearings are flat and use a radial pattern of needles.

Full complement bearings have solid inner and outer rings and rib-guided cylindrical rollers. Since these bearings have the largest possible number of rolling elements, they have extremely high radial load carrying capacity and are suitable for particularly compact designs. 

Needle bearings are heavily used in automobile components such as rocker arm pivots, pumps, compressors, and transmissions. The drive shaft of a rear-wheel drive vehicle typically has at least eight needle bearings (four in each U joint) and often more if it is particularly long, or operates on steep slopes.

Additional clarification of needle roller: According to "Marks' Standard Handbook for Mechanical Engineers", a needle bearing is a roller bearing with rollers whose length are at least four times their diameter.

Tire balance

Tire balance, also referred to as tire unbalance or imbalance, describes the distribution of mass within an automobile tire or the entire wheel to which it is attached.

When the wheel rotates, asymmetries of mass may cause it to hop or wobble, which can cause ride disturbances, usually vertical and lateral vibrations. It can also result in a wobbling of the steering wheel or of the entire vehicle. The ride disturbance, due to unbalance, usually increases with speed. Vehicle suspensions can become excited by unbalance forces when the speed of the wheel reaches a point that its rotating frequency equals the suspension’s resonant frequency.Tires are balanced in factories and repair shops by two methods: static balancers and dynamic balancers. Tires with high unbalance forces are downgraded or rejected. When tires are fitted to wheels at the point of sale, they are measured again on a balancing machine, and correction weights are applied to counteract the combined effect of the tire and wheel unbalance. After sale, tires may be rebalanced if driver perceives excessive vibration.

Semi-automatic transmission

A hybrid form of transmission where an integrated control system handles manipulation of the clutch automatically, but the driver can still—and may be required to—take manual control of gear selection. This is sometimes called a "clutchless manual", or "automated manual" transmission. Many of these transmissions allow the driver to fully delegate gear shifting choice to the control system, which then effectively acts as if it was a regular automatic transmission. They are generally designed using manual transmission "internals", and when used in passenger cars, have synchromesh operated helical constant mesh gear sets.

Early semi-automatic systems used a variety of mechanical and hydraulic systems—including centrifugal clutches, torque converters, electro-mechanical (and even electrostatic) and servo/solenoid controlled clutches—and control schemes—automatic declutching when moving the gearstick, pre-selector controls, centrifugal clutches with drum-sequential shift requiring the driver to lift the throttle for a successful shift, etc.—and some were little more than regular lock-up torque converter automatics with manual gear selection.

Most modern implementations, however, are standard or slightly modified manual transmissions (and very occasionally modified automatics—even including a few cases of CVTs with "fake" fixed gear ratios), with servo-controlled clutching and shifting under command of the central engine computer. These are intended as a combined replacement option both for more expensive and less efficient "normal" automatic systems, and for drivers who prefer manual shift but are no longer able to operate a clutch, and users are encouraged to leave the shift lever in fully automatic "drive" most of the time, only engaging manual-sequential mode for sporty driving or when otherwise strictly necessary.

Specific types of this transmission include: Easytronic, Tiptronic and Geartronic, as well as the systems used as standard in all ICE-powered Smart-MCC vehicles, and on geared step-through scooters such as the Honda Super Cub or Suzuki Address.

A dual-clutch transmission alternately uses two sets of internals, each with its own clutch, so that a "gearchange" actually only consists of one clutch engaging as the other disengages—providing a supposedly "seamless" shift with no break in (or jarring reuptake of) power transmission. Each clutch's attached shaft carries half of the total input gear complement (with a shared output shaft), including synchronised dog clutch systems that pre-select which of its set of ratios is most likely needed at the next shift, under command of a computerised control system. Specific types of this transmission include: Direct-Shift Gearbox.

There are also sequential transmissions that use the rotation of a drum to switch gears, much like those of a typical fully manual motorcycle.These can be designed with a manual or automatic clutch system, and may be found both in automobiles (particularly track and rally racing cars), motorcycles (typically light "step-thru" type city utility bikes, e.g., the Honda Super Cub) and quadbikes (often with a separately engaged reversing gear), the latter two normally using a scooter-style centrifugal clutc

Steering damper

A steering damper, steering stabiliser or sprint damper is a damping device designed to inhibit an undesirable, uncontrolled movement or oscillation of a vehicle steering mechanism, a phenomenon known in motorcycling as wobble, or in extreme cases, a tank-slapper. Modern motorbikes are unlikely to exhibit this behaviour in daily use thanks in part to better dampers and due to their very stiff front ends and other general improvements in design and tyre technology.

Multi-deck diffusers

In 2009, the Formula 1 grid was embroiled in controversy. The culprit was the so-called double-decker diffuser introduced at first by Brawn GP, WilliamsF1, and Toyota Racing, but later put into use by every team. These three teams had exploited a loophole in the rules that allowed for more volume in the diffuser. The rules stated that the diffuser must start at a point aligned with the centerline of the rear wheels. The loophole allowed for holes in the underbody, perpendicular to the reference plane (not visible as a hole when viewed from directly above), that fed a diffuser channel that was above the main diffuser. This greatly increased the available downforce, and was worth about half a second per lap, according to Mike Gascoyne.The teams decided to allow the double-decker diffusers again for 2010. However, for 2011, the Formula 1 Technical Working Group decided to ban multi-deck diffusers.

Diffuser (automotive)

A diffuser, in an automotive context, is a shaped section of the car underbody which improves the car's aerodynamic properties by enhancing the transition between the high-velocity airflow underneath the car and the much slower freestream airflow of the ambient atmosphere. It works by providing a space for the underbody airflow to decelerate and expand (in area, density remains constant at the speeds that cars travel) so that it does not cause excessive flow separation and drag, by providing a degree of "wake infill" or more accurately, pressure recovery. The diffuser itself accelerates the flow in front of it, which helps generate downforce.

Spoiler of Passenger vehicles

The goal of many spoilers used in passenger vehicles is to reduce drag and increase fuel efficiency.Passenger vehicles can be equipped with front and rear spoilers. Front spoilers, found beneath the bumper, are mainly used to decrease the amount of air going underneath the vehicle to reduce the drag coefficient and lift.

Sports cars are most commonly seen with front and rear spoilers. Even though these vehicles typically have a more rigid chassis and a stiffer suspension to aid in high speed maneuverability, a spoiler can still be beneficial. This is because many vehicles have a fairly steep downward angle going from the rear edge of the roof down to the trunk or tail of the car which may cause air flow separation. The flow of air becomes turbulent and a low-pressure zone is created, increasing drag and instability (see Bernoulli effect). Adding a rear spoiler could be considered to make the air "see" a longer, gentler slope from the roof to the spoiler, which helps to delay flow separation and the higher pressure in front of the spoiler can help reduce the lift on the car by creating down force. This may reduce drag in certain instances and will generally increase high speed stability due to the reduced rear lift.

Due to their association with racing, spoilers are often viewed as "sporty" by consumers.

Capacitor

A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energyelectrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e., insulator). The conductors can be thin films of metal, aluminum foil or disks, etc. The 'nonconducting' dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, paper, mica, etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike aresistor, a capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

When there is a potential difference across the conductors (e.g., when a capacitor is attached across a battery), an electric field develops across the dielectric, causing positive charge (+Q) to collect on one plate and negative charge (-Q) to collect on the other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if an accelerating or alternating voltage is applied across the leads of the capacitor, a displacement current can flow.

An ideal capacitor is characterized by a single constant value for its capacitance. Capacitance is expressed as the ratio of theelectric charge (Q) on each conductor to the potential difference (V) between them. The SI unit of capacitance is the farad (F), which is equal to one coulomb per volt (1 C/V). Typical capacitance values range from about 1 pF (10⁻¹² F) to about 1 mF (10⁻³ F).

The capacitance is greater when there is a narrower separation between conductors and when the conductors have a larger surface area. In practice, the dielectric between the plates passes a small amount of leakage current and also has an electric field strength limit, known as the breakdown voltage. The conductors and leads introduce an undesired inductance and resistance.

Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filternetworks, they smooth the output of power supplies. In resonant circuits they tune radios to particular frequencies. In electric power transmission systems they stabilize voltage and power flow.

Brush contact angle

The different brush types make contact with the commutator in different ways. Because copper brushes have the same hardness as the commutator segments, the rotor cannot be spun backwards against the ends of copper brushes without the copper digging into the segments and causing severe damage. Consequently strip/laminate copper brushes only make tangential contact with the commutator, while copper mesh and wire brushes use an inclined contact angle touching their edge across the segments of a commutator that can spin in only one direction.

The softness of carbon brushes permits direct radial end-contact with the commutator without damage to the segments, permitting easy reversal of rotor direction, without the need to reorient the brush holders for operation in the opposite direction. Although never reversed, common appliance motors that use wound rotors, commutators and brushes have radial-contact brushes. In the case of a reaction-type carbon brush holder, carbon brushes may be reversely inclined with the commutator so that the commutator tends to push against the carbon for firm contact.

commutator

A commutator is the moving part of a rotary electrical switch in certain types of electric motors or electrical generators that periodically reverses the current direction between the rotor and the external circuit. Commutators have two or more softer metallic brushes in contact with them to complete the other half of the switch. In a motor, it applies power to the best location on the rotor, and in a generator, picks off power similarly. As a switch, it has exceptionally long life, considering the number of circuit makes and breaks that occur in normal operation.

A commutator is a common feature of direct current rotating machines. By reversing the current direction in the moving coil of a motor's armature, a steady rotating force (torque) is produced. Similarly, in a generator, reversing of the coil's connection to the external circuit provides unidirectional (i.e. direct) current to the external circuit. The first commutator-type direct current machine was built by Hippolyte Pixii in 1832, based on a suggestion by André-Marie Ampère.

Operation of Alternator

Despite their names, both 'DC generators' (or 'dynamos') and 'alternators' initially produce alternating current. In a so-called 'DC generator', this AC current is generated in the rotating armature, and then converted to DC by the commutator and brushes. In an 'alternator', the AC current is generated in the stationary stator, and then is converted to DC by the rectifiers (diodes).

Typical passenger vehicle and light truck alternators use Lundell or 'claw-pole' field construction. This uses a shaped iron core on the rotor to produce a multi-pole field from a single coil winding. The poles of the rotor look like fingers of two hands interlocked with each other. The coil is mounted axially inside this and field current is supplied by slip rings and carbon brushes. These alternators have their field and stator windings cooled by axial airflow, produced by an external fan attached to the drive belt pulley.Larger vehicles may have salient-pole alternators similar to larger machines.Modern vehicles now use the compact alternator layout. This is electrically and magnetically similar, but has improved air cooling. Better cooling permits more power from a smaller machine. The casing has distinctive radial vent slots at each end and now encloses the fan. Two fans are used, one at each end, and the airflow is semi-radial, entering axially and leaving radially outwards. The stator windings now consist of a dense central band where the iron core and copper windings are tightly packed, and end bands where the windings are more exposed for better heat transfer. The closer core spacing from the rotor improves magnetic efficiency. The smaller, enclosed fans produce less noise, particularly at higher machine speeds.

The windings of a 3 phase alternator may be connected using either the Delta or Wye connection regime.  set-up.

Brush less versions of these type alternators are also common in larger machinery such as highway trucks and earth moving machinery. With two oversized shaft bearings as the only wearing parts, these can provide extremely long and reliable service, even exceeding the engine overhaul intervals.

Coolant

A coolant is a fluid which flows through or around a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor promoting corrosion of the cooling system. Some applications also require the coolant to be an electrical insulator.

While the term coolant is commonly used in automotive and HVAC applications, in industrial processing, heat transfer fluid is one technical term more often used, in high temperature as well as low temperature manufacturing applications. Another industrial sense of the word covers cutting fluids.

The coolant can either keep its phase and stay liquid or gaseous, or can undergo a phase transition, with the latent heat adding to the cooling efficiency. The latter, when used to achieve low temperatures, is more commonly known as refrigerant.

Radial tire

A radial tire (more properly, a radial-ply tire) is a particular design of vehicular tire (in British English, tyre). In this design, the cord plies are arranged at 90 degrees to the direction of travel, or radially (from the centre of the tire

A series of plies of cord reinforces a tire. Without this, a tire would be flexible and weak. The network of cords that gives the tire strength and shape is called the carcass. Since the 1960s, all common tires have a carcass of cords of polyester, steel, or other textile materials, inlaid with several layers of rubber.

In the past, the fabric was built up on a flat steel drum, with the cords at angles of about +60 and −60 degrees from the direction of travel, so they criss-crossed over each other. They were called cross-ply or bias ply tires. The plies were turned up around the steel wire beads and the combined tread/sidewall applied. The green (uncured) tire was loaded over a curing bladder and shaped into the mold. This shaping process caused the cords in the tire to assume an S-shape from bead to bead. The angle under the tread, the crown angle, stretched down to about 36 degrees. In the sidewall region the angle was 45 degrees, and in the bead it remained at 60 degrees. The low crown angle gave rigidity to support the tread and the high sidewall angle gave comfort.

By comparison, radial tires lay all of the cord plies at 90 degrees to the direction of travel (that is, across the tire from lip to lip). This design avoids having the plies rub against each other as the tire flexes, reducing the tire's rolling friction. This allows vehicles with radial tires to achieve better fuel economy than with bias-ply tires. It also accounts for the slightly "low on air" (bulging) look that radial tire sidewalls have, especially when compared to bias-ply tires.

The first radial tire designs were patented in 1915 by Arthur W. Savage, a tire manufacturer and inventor in San Diego, CA.  Savage's patents expired in 1949. The design was further developed and commercialized by Michelin; the first Michelin X radial tire for cars was developed in 1946 by Michelin researcher Marius Mignol, and then a radial truck tire in 1952. Because of its advantages, it has now become the standard design for essentially all automotive tires.

Double Cardan Shaft

A configuration known as a double Cardan joint drive shaft partially overcomes the problem of jerky rotation. This configuration uses two U-joints joined by an intermediate shaft, with the second U-joint phased in relation to the first U-joint to cancel the changing angular velocity. In this configuration, the angular velocity of the driven shaft will match that of the driving shaft, provided that both the driving shaft and the driven shaft are at equal angles with respect to the intermediate shaft (but not necessarily in the same plane) and that the two universal joints are 90 degrees out of phase. This assembly is commonly employed in rear wheel drive vehicles, where it is known as a drive shaft or propeller (prop) shaft.

Even when the driving and driven shafts are at equal angles with respect to the intermediate shaft, if these angles are greater than zero, oscillating moments are applied to the three shafts as they rotate. These tend to bend them in a direction perpendicular to the common plane of the shafts. This applies forces to the support bearings and can cause "launch shudder" in rear wheel drive vehicles. The intermediate shaft will also have a sinusoidal component to its angular velocity, which contributes to vibration and stresses.

Mathematically, this can be shown as follows: If  and  are the angles for the input and output of the universal joint connecting the drive and the intermediate shafts respectively, and  and  are the angles for the input and output of the universal joint connecting the intermediate and the output shafts respectively, and each pair are at angle  with respect to each other, then:

If the second universal joint is rotated 90 degrees with respect to the first, then . Using the fact that  yields:

and it is seen that the output drive is just 90 degrees out of phase with the input shaft, 

Constant-velocity joint

Constant-velocity joints (aka homokinetic or CV joints) allow a drive shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. They are mainly used in front wheel drive and many modern rear wheel drive cars with independent rear suspension typically use CV joints at the ends of the rear axle half shafts, and increasingly use them on the prop shafts.

Constant-velocity joints are protected by a rubber boot, a CV gaiter. Cracks and splits in the boot will allow contaminants in, which would cause the joint to wear quickly.

Construction of the chain

There are actually two types of links alternating in the bush roller chain. The first type is inner links, having two inner plates held together by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the outer links, consisting of two outer plates held together by pins passing through the bushings of the inner links. The "bushing less" roller chain is similar in operation though not in construction; instead of separate bushings or sleeves holding the inner plates together, the plate has a tube stamped into it protruding from the hole which serves the same purpose. This has the advantage of removing one step in assembly of the chain.

The roller chain design reduces friction compared to simpler designs, resulting in higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both the inner and outer plates held by pins which directly contacted the sprocket teeth; however this configuration exhibited extremely rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the wear over a greater area; however the teeth of the sprockets still wore more rapidly than is desirable, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and provided rolling contact with the teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain as well. There is even very low friction, as long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is of primary importance for efficient operation as well as correct tensioning.

Timing belt

A timing belt, timing chain or cam belt is a part of an internal combustion engine that synchronizes the rotation of the crankshaft and the camshaft(s) so that the engine's valves open and close at the proper times during each cylinder's intake and exhaust strokes. In an interference engine the timing belt or chain is also critical to preventing the piston from striking the valves. A timing belt is a belt that usually features teeth on the inside surface, while a timing chain is a roller chain.

Most modern production automobile engines utilize a timing belt or chain to synchronize crankshaft and camshaft rotation; some engines instead utilize gears to directly drive the camshafts. The use of a timing belt or chain instead of direct gear drive enables engine designers to place the camshaft(s) further from the crankshaft, and in engines with multiple camshafts a timing belt or chain also enables the camshafts to be placed further from each other. Timing chains were common on production automobiles through the 1970s and 1980s, when timing belts became the norm, but timing chains have seen a resurgence in recent years. Timing chains are generally more durable than timing belts – though neither is as durable as direct gear drive – however, timing belts are lighter, less expensive, and operate more quietly.

Electronic ignition system

The disadvantage of the mechanical system is the use of breaker points to interrupt the low-voltage high-current through the primary winding of the coil; the points are subject to mechanical wear where they ride the cam to open and shut, as well as oxidation and burning at the contact surfaces from the constant sparking. They require regular adjustment to compensate for wear, and the opening of the contact breakers, which is responsible for spark timing, is subject to mechanical variations.

In addition, the spark voltage is also dependent on contact effectiveness, and poor sparking can lead to lower engine efficiency. A mechanical contact breaker system cannot control an average ignition current of more than about 3 A while still giving a reasonable service life, and this may limit the power of the spark and ultimate engine speed.Electronic ignition (EI) solves these problems. In the initial systems, points were still used but they handled only a low current which was used to control the high primary current through a solid state switching system. Soon, however, even these contact breaker points were replaced by an angular sensor of some kind - either optical, where a vaned rotor breaks a light beam, or more commonly using a Hall effect sensor, which responds to a rotating magnet mounted on the distributor shaft. The sensor output is shaped and processed by suitable circuitry, then used to trigger a switching device such as a thyristor, which switches a large current through the coil.

The first electronic ignition (a cold cathode type) was tested in 1948 by Delco-Remy, while Lucas introduced a transistorized ignition in 1955, which was used on BRM andCoventry Climax Formula One engines in 1962. The aftermarket began offering EI that year, with both the AutoLite Electric Transistor 201 and Tung-Sol EI-4 (thyratron capacitive discharge) being available. Pontiac became the first automaker to offer an optional EI, the breakerless magnetic pulse-triggered Delcotronic, on some 1963 models; it was also available on some Corvettes. The first commercially available all solid-state (SCR) capacitive discharge ignition was manufactured by Hyland Electronics in Canada also in 1963. Ford fitted a Lucas system on the Lotus 25s entered at Indianapolis the next year, ran a fleet test in 1964, and began offering optional EI on some models in 1965.Beginning in 1958, Earl W. Meyer at Chrysler worked on EI, continuing until 1961 and resulting in use of EI on the company's NASCAR hemis in 1963 and 1964.

Prest-O-Lite's CD-65, which relied on capacitance discharge (CD), appeared in 1965, and had "an unprecedented 50,000 mile warranty." (This differs from the non-CD Prest-O-Lite system introduced on AMC products in 1972, and made standard equipment for the 1975 model year.) A similar CD unit was available from Delco in 1966, which was optional on Oldsmobile, Pontiac, and GMC vehicles in the 1967 model year. Also in 1967, Motorola debuted their breakerless CD system. The most famous aftermarket electronic ignition which debuted in 1965, was the Delta Mark 10 capacitive discharge ignition, which was sold assembled or as a kit.

FIAT became the first company to offer standard EI, in 1968, followed by Chrysler (after a 1971 trial) in 1973 and by Ford and GM in 1975.

In 1967, Prest-O-Lite made a "Black Box" ignition amplifier, intended to take the load off of the distributor's breaker points during high r.p.m. runs, which was used by Dodge and Plymouth on their factory Super Stock Coronet and Belvedere and drag racers. This amplifier was installed on the interior side of the cars' firewall, and had a duct which provided outside air to cool the unit. The rest of the system (distributor and spark plugs) remains as for the mechanical system. The lack of moving parts compared with the mechanical system leads to greater reliability and longer service intervals.

Chrysler introduced breakerless ignition in mid-1971 as an option for its 340 V8 and the 426 Street Hemi. For the 1972 model year, the system became standard on its high-performance engines (the 340 cu in (5.6 l) and the four-barrel carburetor-equipped 400 hp (298 kW) 400 cu in (7 l)) and was an option on its 318 cu in (5.2 l), 360 cu in (5.9 l), two-barrel 400 cu in (6.6 l), and low-performance 440 cu in (7.2 l) . Breakerless Ignition was standardised across the model range for 1973.

For older cars, it is usually possible to retrofit an EI system in place of the mechanical one. In some cases, a modern distributor will fit into the older engine with no other modifications, like the H.E.I. distributor made by General Motors, the Hot-Spark electronic ignition conversion kit and the aforementioned Chrysler-built electronic ignition system.Other innovations are currently available on various cars. In some models, rather than one central coil, there are individual coils on each spark plug, sometimes known as direct ignition or coil on plug (COP). This allows the coil a longer time to accumulate a charge between sparks, and therefore a higher energy spark. A variation on this has each coil handle two plugs, on cylinders which are 360 degrees out of phase (and therefore reach TDC at the same time); in the four-cycle engine this means that one plug will be sparking during the end of the exhaust stroke while the other fires at the usual time, a so-called "wasted spark" arrangement which has no drawbacks apart from faster spark plug erosion; the paired cylinders are 1/4 and 2/3. Other systems do away with the distributor as a timing apparatus and use a magnetic crank angle sensor mounted on the crankshaft to trigger the ignition at the proper time

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Torque split during operation of limited-slip differential

An open differential has a fixed torque split between the input and outputs. In most cases the relationship is:

• Trq _{out_1} = Trq _{out_2} , where 1 and 2 are typically the left and right drive wheels.

• Trq _in = Trq _{out_1} + Trq _{out_2} .

Thus the wheels always see the same torque even when spinning at different speeds, including the case where one is stationary. Note, the torque split can be unequal, though 50:50 is typical.

A limited-slip differential has a more complex torque-split and should be considered in the case when the outputs are spinning the same speed and when spinning at different speeds. The torque difference between the two axles is called Trq _d . (In this work it is called Trq _f for torque friction). Trq _d is the difference in torque delivered to the left and right wheel. The magnitude of Trq _d comes from the slip-limiting mechanism in the differential and may be a function of input torque (as in the case of a gear differential), or the difference in the output speeds (as in the case of a viscous differential).

The torque delivered to the outputs is:

• Trq ₁ = ½ Trq _in + ½ Trq _d for the slower output

• Trq ₂ = ½ Trq _in – ½ Trq _d for the faster output

When traveling in a straight line, where one wheel starts to slip (and spin faster than the wheel with traction), torque is reduced to the slipping wheel (Trq ₂ ) and provided to the slower wheel (Trq ₁ ).

In the case when the vehicle is turning and neither wheel is slipping, the inside wheel will be turning slower than the outside wheel. In this case the inside wheel will receive more torque than the outside wheel, which can result in understeer.

When both wheels are spinning at the same speed, the torque distribution to each wheel is:

• Trq _{(1 or 2)} = ½ Trq _in ±(½ Trq _d ) while

• Trq ₁ +Trq ₂ =Trq _in .

This means the maximum torque to either wheel is statically indeterminate but is in the range of ½ Trq _in ±( ½ Trq _d ).

Benefits of limited-slip differential

The main advantage of a limited-slip differential is demonstrated by considering the case of a standard (or "open") differential in off-roading or snow situations where one wheel begins to slip or lose contact with the ground. In such a case with a standard differential, the slipping or non-contacting wheel will receive the majority of the power, while the contacting wheel will remain stationary with the ground. The torque transmitted will be equal at both wheels, and therefore, will not exceed the threshold of torque needed to move the wheel with traction. In this situation, a limited-slip differential prevents excessive power from being allocated to one wheel, and thereby keeping both wheels in powered rotation.

Limited-slip differential

A limited-slip differential (LSD) is a type of automotive differential gear arrangement that allows for some difference in angular velocityof the output shafts, but imposes a mechanical bound on the disparity.

In an automobile, such limited-slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.

Locking differential

A locking differential, differential lock, diff lock or locker is a variation on the standard automotive differential. A locking differential may provide increased traction compared to a standard, or "open" differential by restricting each of the two wheels on an axle to the same rotational speed without regard to available traction or differences in resistance seen at each wheel.

A locking differential is designed to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction (or lack thereof) available to either wheel individually.

When the differential is unlocked (open differential), it allows each wheel to rotate at different speeds (such as when negotiating a turn), thus avoiding tire scuffing. An open (or unlocked) differential always provides the same torque (rotational force) to each of the two wheels, on that axle. So although the wheels can rotate at different speeds, they apply the same rotational force, even if one is entirely stationary, and the other spinning. (Equal torque, unequal rotational speed).

By contrast, a locked differential forces both left and right wheels on the same axle to rotate at the same speed under nearly all circumstances, without regard to tractional differences seen at either wheel. Therefore, each wheel can apply as much rotational force as the traction under it will allow, and the torques on each side-shaft will be unequal. (Unequal torque, equal rotational speeds). Exceptions apply to automatic lockers, discussed below.

A locked differential can provide a significant traction advantage over an open differential, but only when the traction under each wheel differs significantly.

All the above comments apply to central differentials as well as to those in each axle: full-time four-wheel-drive (more accurately as "All Wheel Drive") vehicles have three differentials, one in each axle, and a central one between the front and rear axles (transfer case).

Diesel Oxidation Catalyst

For compression-ignition (i.e., diesel engines), the most commonly used catalytic converter is the Diesel Oxidation Catalyst (DOC). This catalyst uses O₂ (oxygen) in the exhaust gas stream to convert CO (carbon monoxide) to CO₂ (carbon dioxide) and HC (hydrocarbons) to H₂O (water) and CO₂. These converters often operate at 90 percent efficiency, virtually eliminating diesel odor and helping to reduce visible particulates (soot). These catalysts are not active for NO_x reduction because any reductant present would react first with the high concentration of O₂ in diesel exhaust gas.

Reduction in NO_x emissions from compression-ignition engines has previously been addressed by the addition of exhaust gas to incoming air charge, known as exhaust gas recirculation (EGR). In 2010, most light-duty diesel manufacturers in the U.S. added catalytic systems to their vehicles to meet new federal emissions requirements. There are two techniques that have been developed for the catalytic reduction of NO_x emissions under lean exhaust conditions - selective catalytic reduction (SCR) and the lean NO_x trap or NOx adsorber. Instead of precious metal-containing NOx adsorbers, most manufacturers selected base-metal SCR systems that use a reagent such as ammonia to reduce the NO_x into nitrogen. Ammonia is supplied to the catalyst system by the injection of urea into the exhaust, which then undergoes thermal decomposition and hydrolysis into ammonia. One trademark product of urea solution, also referred to as Diesel Exhaust Fluid (DEF), is AdBlue.

Diesel exhaust contains relatively high levels of particulate matter (soot), consisting in large part of elemental carbon. Catalytic converters cannot clean up elemental carbon, though they do remove up to 90 percent of the soluble organic fraction, so particulates are cleaned up by a soot trap or diesel particulate filter (DPF). Historically, a DPF consists of a Cordierite or Silicon Carbide substrate with a geometry that forces the exhaust flow through the substrate walls, leaving behind trapped soot particles. Contemporary DPFs can be manufactured from a variety of rare metals that provide superior performance (at a greater expense). As the amount of soot trapped on the DPF increases, so does the back pressure in the exhaust system. Periodic regenerations (high temperature excursions) are required to initiate combustion of the trapped soot and thereby reducing the exhaust back pressure. The amount of soot loaded on the DPF prior to regeneration may also be limited to prevent extreme exotherms from damaging the trap during regeneration. In the U.S., all on-road light, medium and heavy-duty vehicles powered by diesel and built after 1 January 2007, must meet diesel particulate emission limits that means they effectively have to be equipped with a 2-Way catalytic converter and a diesel particulate filter. Note that this applies only to the diesel engine used in the vehicle. As long as the engine was manufactured before 1 January 2007, the vehicle is not required to have the DPF system. This led to an inventory runup by engine manufacturers in late 2006 so they could continue selling pre-DPF vehicles well into 2007. During the re-generation cycle, most systems require the engine to consume several gallons of fuel in a relatively short amount of time in order to generate the high temperatures necessary for the cycle to complete. This has been shown to adversely affect the overall fuel economy of vehicles equipped with DPF systems, especially in vehicles that are driven mostly in city conditions where frequent acceleration requires a larger amount of fuel to be burned and therefore more soot to collect in the exhaust system.

Types of Catalytic converter

Two-way

A two-way (or "oxidation") catalytic converter has two simultaneous tasks:

1. Oxidation of carbon monoxide to carbon dioxide: 2CO + O₂ → 2CO₂
2. Oxidation of hydrocarbons (unburnt and partially burnt fuel) to carbon dioxide and water: C_xH_2x+2 + [(3x+1)/2] O₂ → xCO₂ + (x+1) H₂O (a combustion reaction)

This type of catalytic converter is widely used on diesel engines to reduce hydrocarbon and carbon monoxide emissions. They were also used on gasoline engines in American- and Canadian-market automobiles until 1981. Because of their inability to control oxides of nitrogen, they were superseded by three-way converters.

Three-way

Three-way catalytic converters (TWC) have the additional advantage of controlling the emission of nitrogen oxides (NO_x), in particular nitrous oxide, a greenhouse gas over three hundred times more potent than carbon dioxide, a precursor to acid rain and currently the most ozone-depleting substance. Technological improvements including three-way catalytic converters have led to motor vehicle nitrous oxide emissions in the US falling to 8.2% of anthropogenic nitrous oxide emissions in 2008, from a high of 17.77% in 1998.

Since 1981, "three-way" (oxidation-reduction) catalytic converters have been used in vehicle emission control systems in the United States and Canada; many other countries have also adopted stringent vehicle emission regulations that in effect require three-way converters on gasoline-powered vehicles. The reduction and oxidation catalysts are typically contained in a common housing, however in some instances they may be housed separately. A three-way catalytic converter has three simultaneous tasks:

1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NO_x → xO₂ + N₂
2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O₂ → 2CO₂
3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: C_xH_2x+2 + [(3x+1)/2]O₂ → xCO₂ + (x+1)H₂O.

These three reactions occur most efficiently when the catalytic converter receives exhaust from an engine running slightly above the stoichiometric point. This point is between 14.6 and 14.8 parts air to 1 part fuel, by weight, for gasoline. The ratio for Autogas (or liquefied petroleum gas (LPG)), natural gas and ethanol fuels is each slightly different, requiring modified fuel system settings when using those fuels. In general, engines fitted with 3-way catalytic converters are equipped with a computerized closed-loop feedbackfuel injection system using one or more oxygen sensors, though early in the deployment of three-way converters, carburetors equipped for feedback mixture control were used.

Three-way catalysts are effective when the engine is operated within a narrow band of air-fuel ratios near stoichiometry, such that the exhaust gas oscillates between rich (excess fuel) and lean (excess oxygen) conditions. However, conversion efficiency falls very rapidly when the engine is operated outside of that band of air-fuel ratios. Under lean engine operation, there is excess oxygen and the reduction of NO_x is not favored. Under rich conditions, the excess fuel consumes all of the available oxygen prior to the catalyst, thus only stored oxygen is available for the oxidation function. Closed-loop control systems are necessary because of the conflicting requirements for effective NO_x reduction and HC oxidation. The control system must prevent the NO_x reduction catalyst from becoming fully oxidized, yet replenish the oxygen storage material to maintain its function as an oxidation catalyst.

Three-way catalytic converters can store oxygen from the exhaust gas stream, usually when the air–fuel ratio goes lean. When sufficient oxygen is not available from the exhaust stream, the stored oxygen is released and consumed (see cerium(IV) oxide). A lack of sufficient oxygen occurs either when oxygen derived from NO_x reduction is unavailable or when certain maneuvers such as hard acceleration enrich the mixture beyond the ability of the converter to supply oxygen.

Supersession of carburetors

In the 1970s and 1980s in the US and Japan, the respective federal governments imposed increasingly strict exhaust emission regulations. During that time period, the vast majority of gasoline-fueled automobile and light truck engines did not use fuel injection. To comply with the new regulations, automobile manufacturers often made extensive and complex modifications to the engine carburetor(s). While a simple carburetor system is cheaper to manufacture than a fuel injection system, the more complex carburetor systems installed on many engines in the 1970s were much more costly than the earlier simple carburetors. To more easily comply with emissions regulations, automobile manufacturers began installing fuel injection systems in more gasoline engines during the late 1970s.

The open loop fuel injection systems had already improved cylinder-to-cylinder fuel distribution and engine operation over a wide temperature range, but did not offer further scope to sufficient control fuel/air mixtures, in order to further reduce exhaust emissions. Later Closed loop fuel injection systems improved the air/fuel mixture control with an exhaust gas oxygen sensor and began incorporating a catalytic converter to further reduce exhaust emissions.

Fuel injection was phased in through the latter 1970s and 80s at an accelerating rate, with the German, French, and U.S. markets leading and the UK and Commonwealth markets lagging somewhat. Since the early 1990s, almost all gasoline passenger cars sold in first world markets are equipped with electronic fuel injection (EFI). The carburetor remains in use in developing countries where vehicle emissions are unregulated and diagnostic and repair infrastructure is sparse. Fuel injection is gradually replacing carburetors in these nations too as they adopt emission regulations conceptually similar to those in force in Europe, Japan, Australia, and North America.

Many motorcycles still utilize carburetored engines, though all current high-performance designs have switched to EFI.

NASCAR finally replaced carburetors with fuel-injection, starting at the beginning of the 2012 NASCAR Sprint Cup Series season.

Electric pump

In many modern cars the fuel pump is usually electric and located inside the fuel tank fuel tank. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode (seeflammability limit) and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.

The ignition switch does not carry the power to the fuel pump; instead, it activates a relay which will handle the higher current load. It is common for the fuel pump relay to become oxidized and cease functioning; this is much more common than the actual fuel pump failing. Modern engines utilize solid-state control which allows the fuel pressure to be controlled via pulse-width modulation of the pump voltage. This increases the life of the pump, allows a smaller and lighter device to be used, and reduces electrical load.

Cars with electronic fuel injection have an electronic control unit (ECU) and this may be programmed with safety logic that will shut the electric fuel pump off, even if the engine is running. In the event of a collision this will prevent fuel leaking from any ruptured fuel line. Additionally, cars may have aninertia switch (usually located underneath the front passenger seat) that is "tripped" in the event of an impact, or a roll-over valve that will shut off the fuel pump in case the car rolls over.

Some ECUs may also be programmed to shut off the fuel pump if they detect low or zero oil pressure, for instance if the engine has suffered a terminal failure (with the subsequent risk of fire in the engine compartment).

The fuel sending unit assembly may be a combination of the electric fuel pump, the filter, the strainer, and the electronic device used to measure the amount of fuel in the tank via a float attached to a sensor which sends data to the dash-mounted fuel gauge. The fuel pump by itself is a relatively inexpensive part. But a mechanic at a garage might have a preference to install the entire unit assembly.

Six-stroke engine

The six-stroke engine is a type of internal combustion engine based on the four-stroke engine, but with additional complexity intended to make it more efficient and reduce emissions. Three types of six-stroke engine have been developed since the 1890s:

In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke. The pistons in this type of six-stroke engine go up and down three times for each injection of fuel. There are two power strokes: one with fuel, the other with steam or air.

The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine but also increases the compression ratio.

Internal combustion engine

The internal combustion engine (ICE) is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine the expansion of the high-temperature and high-pressure gases produced by combustion apply direct force to some component of the engine. The force is applied typically to pistons, turbine blades, or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy. The first commercially successful internal combustion engine was created by Étienne Lenoir.

The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine. A second class of internal combustion engines use continuous combustion: gas turbines, jet engine sand most rocket engines, each of which are internal combustion engines on the same principle as previously described.

The ICE is quite different from external combustion engines, such as steam or Stirling engines, in which the energy is delivered to a working fluid not consisting of, mixed with, or contaminated by combustion products. Working fluids can be air, hot water, pressurized water or even liquid sodium, heated in a boiler. ICEs are usually powered by energy-dense fuels such as gasoline or diesel, liquids derived from fossil fuels. While there are many stationary applications, most ICEs are used in mobile applications and are the dominant power supply for cars, aircraft, and boats.

working of air horn

An air horn consists of a flaring metal or plastic horn or trumpet (called the "bell") attached to a small air chamber containing a metal reed or diaphragm in the throat of the horn. Compressed air flows from an inlet line through a narrow opening past the reed or diaphragm, causing it to vibrate, which creates sound waves. The flaring horn serves as an acoustic "transformer" to improve the transfer of sound energy from the diaphragm to the open air, making the sound louder. In most horns it also determines the pitch of the sound. When vibrated by the diaphragm, the column of air in the horn vibrates in standing waves. The length of the horn determines the wavelength of the sound waves generated, and thus the fundamental frequency (pitch) of the note produced by the horn. The longer the horn, the lower the pitch.

Larger air horns used on ships and foghorns function similarly to a whistle; instead of a diaphragm the air escapes from a closed cylindrical resonator chamber through a precisely-shaped slit directed against a knife edge (fipple). The air blowing past the knife edge oscillates, creating sound waves. The oscillations excite standing waves in the resonator chamber, so the length of the chamber determines the pitch of the note produced.

Manual transmission

A manual transmission, also known as a manual gearbox, stick shift (for vehicles with hand-lever shifters), standard transmission or simply a manual, is type of transmission used in motor vehicle applications. It uses a driver-operated clutch engaged and disengaged by a foot pedal (automobile) or hand lever (motorcycle), for regulating torque transfer from the engine to the transmission; and a gear stick operated by foot (motorcycle) or by hand (automobile).

A conventional, 5 or 6-speed manual transmission is often the standard equipment in a base-model car; other options include automated transmissions such as an automatic transmission (often a manumatic), a semi-automatic transmission, or a continuously variable transmission

Recirculating ball

Recirculating ball, also known as recirculating ball and nut or worm and sector, is a steering mechanism commonly found in older automobiles, off-road vehicles, and some trucks. Most newer cars use the more economical rack and pinion steering instead, but some manufacturers (including Chrysler and General Motors) still use this technology in some models; e.g. the Jeep Wrangler and the Crossfire for the durability and strength inherent in the design.

Rack and pinion

A rack and pinion is a type of linear actuator that comprises a pair of gears which convert rotational motion into linear motion. A circular gear called "the pinion" engages teeth on a linear "gear" bar called "the rack"; rotational motion applied to the pinion causes the rack to move, thereby translating the rotational motion of the pinion into the linear motion of the rack.

For example, in a rack railway, the rotation of a pinion mounted on a locomotive or a railcar engages a rack between the rails and forces a train up a steep slope.

For every pair of conjugate involute profile, there is a basic rack. This basic rack is the profile of the conjugate gear of infinite pitch radius. (I.e. a toothed straight edge.)

A generating rack is a rack outline used to indicate tooth details and dimensions for the design of a generating tool, such as a hob or a gear shaper cutter.

Air suspension

Air suspension is a type of vehicle suspension powered by an electric or engine driven air pump or compressor. This compressor pumps the air into a flexible bellows, usually made from textile-reinforced rubber. This in turn inflates the bellows, and raises the chassis from the axle.

Air suspension is often used in place of conventional steel springs, and in heavy vehicle applications such as buses and trucks. The purpose of air suspension is to provide a smooth, constant ride quality, but in some cases is used for sporty suspensions. Modern electronically controlled systems in automobiles and light trucks almost always feature self-leveling along with raising and lowering functions. Although traditionally called air bags or air bellows, the correct term is air spring (although these terms are also used to describe just the rubber bellows element with its end plates).

Common air suspension problems

Air bag or air strut failure is usually caused by wet rot, due to old age, or moisture within the air system that damages it from the inside. Air ride suspension parts may fail because rubber dries out. Punctures to the air bag may be caused from debris on the road. With custom applications, improper installation may cause the air bags to rub against the vehicle's frame or other surrounding parts, damaging it. The over-extension of an airspring which is not sufficiently constrained by other suspension components, such as a shock absorber, may also lead to the premature failure of an airspring through the tearing of the flexible layers. Failure of an airspring may also result in complete immobilization of the vehicle, since the vehicle will rub against the ground or be too high to move. However, most modern automotive systems have overcome many of these problems.

Air line failure is a failure of the tubing which connects the air bags or struts to the rest of the air system, and is typically DOT-approved nylon air brake line. This usually occurs when the air lines, which must be routed to the air bags through the chassis of the vehicle, rub against a sharp edge of a chassis member or a moving suspension component, causing a hole to form. This mode of failure will typically take some time to occur after the initial installation of the system, as the integrity of a section of air line is compromised to the point of failure due to the rubbing and resultant abrasion of the material. An air-line failure may also occur if a piece of road debris hits an air line and punctures or tears it, although this is unlikely to occur in normal road use. It does occur in harsh off-road conditions but it still not common if correctly installed.

Air fitting failure usually occurs when they are first fitted or very rarely in use. Cheap low quality components tend to be very unreliable. Air fittings are used to connect components such as bags, valves, and solenoids to the airline that transfers the air. They are screwed into the component and for the most part push-in or push-to-fit DOT line is then inserted into the fitting.

Compressor failure is primarily due to leaking air springs or air struts. The compressor will burn out trying to maintain the correct air pressure in a leaking air system. Compressor burnout may also be caused by moisture from within the air system coming into contact with its electronic parts. This is far more likely to occur with low specification compressors with insufficient duty cycle which are often purchased due to low cost. For redundancy in the system two compressors are often a better option.

In Dryer failure the dryer, which functions to remove moisture from the air system, eventually becomes saturated and unable to perform that function. This causes moisture to build up in the system and can result in damaged air springs and/or a burned out compressor.