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33-524: A motor vehicle's driveline or drivetrain consists of the parts of the powertrain excluding the engine. It is the portion of a vehicle, after the prime mover , that changes depending on whether a vehicle is front-wheel , rear-wheel , or four-wheel drive , or less-common six-wheel or eight-wheel drive . In a wider sense, the powertrain includes all of the components used to transform stored (chemical, solar, nuclear, kinetic, potential, etc.) energy into kinetic energy for propulsion purposes. This includes

66-415: A motor vehicle , the powertrain consists of the source of propulsion (e.g. the engine or electric motor) and the drivetrain system which transfers this energy into forward movement of the vehicle. The powertrain consists of the prime mover (e.g. an internal combustion engine and/or one or more traction motors) and the drivetrain - all of the components that convert the prime mover's power into movement of

99-401: A common shaft. This forces both wheels to turn in unison, regardless of the traction (or lack thereof) available to either wheel individually. When this function is not required, the differential can be "unlocked" to function as a regular open differential. Locking differentials are mostly used on off-road vehicles, to overcome low-grip and variable grip surfaces. An undesirable side-effect of

132-426: A gearing reduction by having fewer teeth on the pinion than the ring gear . Milestones in the design or use of differentials include: During cornering, the outer wheels of a vehicle must travel further than the inner wheels (since they are on a larger radius). This is easily accommodated when the wheels are not connected , however it becomes more difficult for the drive wheels , since both wheels are connected to

165-432: A hybrid vehicle includes a charging socket, it is considered to be a plug-in hybrid , while vehicles that do not include a charging socket (therefore relying on the engine or regenerative braking to charge the batteries) are considered to be mild hybrids . Differential (mechanical device) A differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft

198-412: A pointer which constantly pointed to the south, no matter how the chariot turned as it travelled. It could therefore be used as a type of compass . It is widely thought that a differential mechanism responded to any difference between the speeds of rotation of the two wheels of the chariot, and turned the pointer appropriately. However, the mechanism was not precise enough, and, after a few miles of travel,

231-494: A regular ("open") differential is that it can send most of the power to the wheel with the lesser traction (grip). In situation when one wheel has reduced grip (e.g. due to cornering forces or a low-grip surface under one wheel), an open differential can cause wheelspin in the tyre with less grip, while the tyre with more grip receives very little power to propel the vehicle forward. In order to avoid this situation, various designs of limited-slip differentials are used to limit

264-454: A type of mechanical analogue computer, were used from approximately 1900 to 1950. These devices used differential gear trains to perform addition and subtraction. The Mars rovers Spirit and Opportunity (both launched in 2004) used differential gears in their rocker-bogie suspensions to keep the rover body balanced as the wheels on the left and right move up and down over uneven terrain. The Curiosity and Perseverance rovers used

297-595: Is achieved through metrology technology applied to all of the steps in powertrain manufacturing processes. In automotive manufacturing, the frame plus the "running gear" makes the chassis . Later, a body (sometimes referred to as " coachwork "), which is usually not necessary for integrity of the structure, is built on the chassis to complete the vehicle . Commercial vehicle manufacturers may have "chassis only" and "cowl and chassis" versions that can be outfitted with specialized bodies. These include buses , motor homes , fire engines , ambulances , etc. The frame plus

330-733: Is important to industry, including the automotive and other vehicle sectors. Competitiveness drives companies to engineer and produce powertrain systems that over time are more economical to manufacture, higher in product quality and reliability, higher in performance, more fuel efficient, less polluting, and longer in life expectancy. In turn these requirements have led to designs involving higher internal pressures, greater instantaneous forces, and increased complexity of design and mechanical operation. The resulting designs in turn impose significantly more severe requirements on parts shape and dimension; and material surface flatness , waviness , roughness , and porosity . Quality control over these parameters

363-427: Is the average of the speeds of the others. A common use of differentials is in motor vehicles , to allow the wheels at each end of a drive axle to rotate at different speeds while cornering. Other uses include clocks and analogue computers . Differentials can also provide a gear ratio between the input and output shafts (called the "axle ratio" or "diff ratio"). For example, many differentials in motor vehicles provide

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396-580: Is the last in the set of components which delivers torque to the drive wheels . In a road vehicle, it incorporates the differential . In a railway vehicle, it sometimes incorporates the reversing gear. Examples include the Self-Changing Gears RF 28 (used in many first-generation diesel multiple units of British Railways ) and RF 11 used in the British Rail Class 03 and British Rail Class 04 diesel shunting locomotives. In

429-574: The British Rail Class 03 and British Rail Class 04 diesel shunting locomotives. This section uses infographics to show a unified model with variations, the green wheels denote no traction, and the angled wheels denote steering. 6X4 means 6 wheel ends and 4 positions distribute power (power divider installed) 6X2 means 6 wheel ends and 2 positions distribute power (single axle drive) 4X0 means 4 wheel ends no power (Trailer axle) 4x2 means 4 Wheel ends, 2 Positions to distribute power The 6 wheel ends can either be wide base singles or duals. Its about

462-401: The engine and/or motor(s) as well as the drivetrain. The function of the drivetrain is to couple the engine that produces the power to the driving wheels that use this mechanical power to rotate the axle. This connection involves physically linking the two components, which may be at opposite ends of the vehicle and so requiring a long propeller shaft or drive shaft . The operating speed of

495-640: The gasoline direct injection variant, as well as improving volumetric efficiency by using multi-valves per cylinder, variable valve timing , variable length intake manifolds , and turbocharging . Changes also include new fuel qualities (no sulphur or aromates ) to allow new combustion concepts. So-called "combined combustion systems" (CCV) or "diesotto" cycles are based on synthetic fuels (synthetic diesel, biomass to liquid (BTL) or gas to liquid (GTL)). BEVs , FCEVs and PHEV powertrains are expected to reach cost parity with ICE powertrains in 2025. The manufacturing of powertrain components and systems

528-449: The "correct" time, so an ordinary clock would frequently have to be readjusted, even if it worked perfectly, because of seasonal variations in the equation of time. Williamson's and other equation clocks showed sundial time without needing readjustment. Nowadays, we consider clocks to be "correct" and sundials usually incorrect, so many sundials carry instructions about how to use their readings to obtain clock time. Differential analysers ,

561-621: The Sun and Moon position pointers. The ball was painted black and white in hemispheres, and graphically showed the phase of the Moon at a particular point in time. An equation clock that used a differential for addition was made in 1720. In the 20th century, large assemblies of many differentials were used as analogue computers , calculating, for example, the direction in which a gun should be aimed. Chinese south-pointing chariots may also have been very early applications of differentials. The chariot had

594-427: The body makes a glider (a vehicle without a powertrain). The final drive is the last in the set of components which delivers torque to the drive wheels . In a road vehicle, it incorporates the differential . In a railway vehicle, it sometimes incorporates the reversing gear. Examples include the Self-Changing Gears RF 28 (used in many first-generation diesel multiple units of British Railways ) and RF 11 used in

627-551: The carrier is rotated (by the input torque), the relationship between the speeds of the input (i.e. the carrier) and that of the output shafts is the same as other types of open differentials. Uses of spur-gear differentials include the Oldsmobile Toronado American front-wheel drive car. Locking differentials have the ability to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on

660-432: The combustion engine and the electric motor have to be brought together and distributed to the wheels. The control of this process can be quite involved but the rewards are greatly improved acceleration and much lower emissions. Powertrain development for diesel engines involves the following: exhaust gas recirculation (EGR), and advanced combustion. Spark ignition engine development include: fuel injection , including

693-408: The dial could be pointing in the wrong direction. The earliest verified use of a differential was in a clock made by Joseph Williamson in 1720. It employed a differential to add the equation of time to local mean time , as determined by the clock mechanism, to produce solar time , which would have been the same as the reading of a sundial . During the 18th century, sundials were considered to show

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726-480: The difference in power sent to each of the wheels. Torque vectoring is a technology employed in automobile differentials that has the ability to vary the torque to each half-shaft with an electronic system; or in rail vehicles which achieve the same using individually motored wheels. In the case of automobiles, it is used to augment the stability or cornering ability of the vehicle. Non-automotive uses of differentials include performing analogue arithmetic . Two of

759-480: The differential's three shafts are made to rotate through angles that represent (are proportional to) two numbers, and the angle of the third shaft's rotation represents the sum or difference of the two input numbers. The earliest known use of a differential gear is in the Antikythera mechanism, c. 80 BCE, which used a differential gear to control a small sphere representing the Moon from the difference between

792-405: The engine (usually via a transmission). Some vehicles (for example go-karts and trams ) use axles without a differential, thus relying on wheel slip when cornering. However, for improved cornering abilities, many vehicles use a differential, which allows the two wheels to rotate at different speeds. The purpose of a differential is to transfer the engine's power to the wheels while still allowing

825-449: The engine and wheels are also different and must be matched by the correct gear ratio . As the vehicle speed changes, the ideal engine speed must remain approximately constant for efficient operation and so this gearbox ratio must also be changed, either manually, automatically or by an automatic continuous variation . The precise components of the drivetrain vary, according to the type of vehicle. Some typical examples: The final drive

858-420: The engine or motor that generates the power. In marine applications, the drive shaft will drive a propeller , thruster, or waterjet rather than a drive axle , while the actual engine might be similar to an automotive engine. Other machinery, equipment and vehicles may also use a drivetrain to deliver power from the engine(s) to the driven components. In contrast, the powertrain is considered to include both

891-401: The front axle and the rear axle in an all-wheel drive vehicle. An advantage of the epicyclic design is that it is relatively compact width (when viewed along the axis of its input shaft). A spur-gear differential has an equal-sized spur gears at each end, each of which is connected to an output shaft. The input torque (i.e. from the engine or transmission) is applied to the differential via

924-405: The outside of the wheels. Drivetrain A drivetrain (also frequently spelled as drive train or sometimes drive-train ) or transmission system , is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering , the drivetrain is the components of a motor vehicle that deliver power to the drive wheels . This excludes

957-410: The propshaft to the half-shafts) and provide a reduction in the gear ratio . The components of the ring-and-pinion differential shown in the schematic diagram on the right are: 1. Output shafts ( axles ) 2. Drive gear 3. Output gears 4. Planetary gears 5. Carrier 6. Input gear 7. Input shaft ( driveshaft ) An epicyclic differential uses epicyclic gearing to send certain proportions of torque to

990-418: The rotating carrier. Pinion pairs are located within the carrier and rotate freely on pins supported by the carrier. The pinion pairs only mesh for the part of their length between the two spur gears, and rotate in opposite directions. The remaining length of a given pinion meshes with the nearer spur gear on its axle. Each pinion connects the associated spur gear to the other spur gear (via the other pinion). As

1023-406: The utilization of multiple power-sources and non–wheel-based vehicles. The most recent developments in powertrain are driven by the electrification of it in multiple components. Electrical energy needs to be provided, usually this leads to larger batteries. Electric motors can be found as isolated component or as part of other elements, e.g. the axle . In hybrid powertrains the torque generated by

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1056-642: The vehicle (e.g. the transmission , driveshafts , differential and axles ); whereas the drivetrain does not include the power source and consists of the transmission, driveshafts, differential and axles. Most passenger cars and commercial vehicles are powered by either an internal combustion engine , electric motor (s) or a combination of the two. The most common types of internal combustion engines are: Most purely electric vehicles use batteries for energy storage and are referred to as battery electric vehicles . Vehicles with both internal combustion engines and electric motors are called hybrid vehicles . If

1089-400: The wheels to rotate at different speeds when required. An illustration of the operating principle for a ring-and-pinion differential is shown below. A relatively simple design of differential is used in rear-wheel drive vehicles, whereby a ring gear is driven by a pinion gear connected to the transmission. The functions of this design are to change the axis of rotation by 90 degrees (from

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