In a

motor vehicle A motor vehicle, also known as a motorized vehicle, automotive vehicle, automobile, or road vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on railway track, rails (such as trains or trams), does not fly (such ...

, the powertrain comprises the main components that generate power and deliver that power to the road surface, water, or air. This includes the

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...

, transmission,

drive shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power (physics), power, torque, and rotation, usually ...

s, differentials, and the final drive ( drive wheels,

continuous track Continuous track or tracked treads are a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the w ...

as in military tanks or caterpillar tractors,

propeller A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working flu ...

, etc.). Hybrid powertrains also include one or more electric traction motors that operate to drive the vehicle wheels. All-electric vehicles ("electric cars") eliminate the engine altogether, relying solely on electric motors for propulsion. Occasionally the term powerplant is casually used to refer to the engine or, less often, the entire powertrain. A motor vehicle's driveline or

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 driv ...

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 A four-wheel drive, also called 4×4 ("four by four") or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case pr ...

, or less-common six-wheel or

eight-wheel drive Eight-wheel drive, often notated as 8WD or 8×8, is a drivetrain configuration that allows all eight wheels of an eight-wheeled vehicle to be drive wheels simultaneously. Unlike four-wheel drive drivetrains, the configuration is largely confin ...

. 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 the utilization of multiple power-sources and non–wheel-based vehicles.

Developments

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 An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...

. In hybrid powertrains the

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

generated by 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 engine The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...

s involves the following:

exhaust gas recirculation In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide () emissions reduction technique used in petrol engine, petrol/gasoline, diesel engines and some hydrogen internal combustion engine vehicle, hydrogen engines. ...

(EGR), and advanced combustion.

Spark ignition A spark-ignition engine (SI engine) is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, ...

engine development include:

fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of a fuel injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All c ...

, including the

gasoline direct injection Gasoline direct injection (GDI), also known as petrol direct injection (PDI), is a fuel injection system for internal combustion engines that run on gasoline (petrol) which injects fuel directly into the combustion chamber. This is distinct f ...

variant, as well as improving volumetric efficiency by using

multi-valve A multi-valve or multivalve Four-stroke engine, four-stroke internal combustion engine is one where each Cylinder (engine), cylinder has ''more than two'' poppet valve, valves – more than the minimum required of one of each, for the purposes of ...

s per cylinder,

variable valve timing Variable valve timing (VVT) is the process of altering the timing of a Poppet valve, valve lift event in an internal combustion engine, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combina ...

, 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 Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

powertrains in 2025.

Key Components

The powertrain of a vehicle refers to the collection of components that generate power and deliver it to the wheels, enabling the vehicle to move. Powertrains can vary significantly between conventional internal combustion engine (ICE) vehicles, hybrid vehicles (HEVs), and electric vehicles (EVs). Regardless of the type, the powertrain remains one of the most critical systems in any vehicle. * Engine: The engine is the heart of the powertrain in conventional ICE vehicles. It converts fuel, such as gasoline or diesel, into mechanical energy through the process of combustion. Engines come in various forms, including internal combustion engines, which are the most common, and electric motors, which are predominant in EVs. Hybrid vehicles often combine both systems to maximize fuel efficiency and reduce emissions. Each engine type has its unique design and operational characteristics, but all aim to produce the torque required to propel the vehicle. * Electric Motor and Inverter:In electric vehicles, the electric motor replaces the traditional engine, converting electrical energy into mechanical energy to drive the wheels. This motor is highly efficient and eliminates the need for some of the more complex components found in ICE vehicles, such as exhaust systems or fuel tanks. Inverters are critical in EVs, as they control the motor's performance by regulating power output and enabling variable speeds. Together, the motor and inverter form the backbone of the electric powertrain. * Transmission:The transmission is responsible for transferring mechanical energy from the engine or motor to the drivetrain. It ensures that the power generated by the engine is delivered to the wheels in the most efficient manner, adjusting for speed and load. There are several types of transmissions, including manual transmissions, where the driver shifts gears; automatic transmissions, which shift gears automatically; continuously variable transmissions (CVTs), which offer seamless acceleration; and dual-clutch transmissions (DCTs), known for their rapid gear changes and improved performance. * Control Units:Modern powertrains are heavily dependent on electronic control units (ECUs) or powertrain control modules (PCMs). These systems monitor and optimize the performance of the engine, transmission, and other components. By analyzing data from sensors throughout the vehicle, ECUs ensure the powertrain operates at peak efficiency while also complying with emissions and performance standards. Control units are essential for advanced features like adaptive driving modes and predictive maintenance. * Drivetrain:The drivetrain is the system that connects the transmission to the wheels, distributing power as needed. It includes key components such as the driveshaft, which transfers rotational power, the differential, which allows the wheels to rotate at different speeds for smoother cornering, and the axles, which deliver power directly to the wheels. The drivetrain configuration varies by vehicle type, with common setups being front-wheel drive (FWD), rear-wheel drive (RWD), and all-wheel drive (AWD) or four-wheel drive (4WD), each offering distinct advantages depending on the application.

Manufacturing

The manufacturing of powertrain components and systems 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 Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

Quality control Quality control (QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as "a part of quality management focused on fulfilling quality requirements". This approach plac ...

over these parameters is achieved through

metrology Metrology is the scientific study of measurement. It establishes a common understanding of Unit of measurement, units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to stan ...

technology applied to all of the steps in powertrain manufacturing processes.

Frames and powertrains

In automotive manufacturing, the frame plus the "running gear" makes the

chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of a manufactured object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart ...

. Later, a body (sometimes referred to as "

coachwork A coachbuilder manufactures bodies for passenger-carrying vehicles. The trade of producing coachwork began with bodies for horse-drawn vehicles. Today it includes custom automobiles, buses, motor coaches, and railway carriages. The word ...

"), which is usually not necessary for integrity of the structure, is built on the chassis to complete the

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

. 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 engine A fire engine or fire truck (also spelled firetruck) is a vehicle, usually a specially designed or modified truck, that functions as a firefighting apparatus. The primary purposes of a fire engine include transporting firefighters and water to ...

ambulance An ambulance is a medically-equipped vehicle used to transport patients to treatment facilities, such as hospitals. Typically, out-of-hospital medical care is provided to the patient during the transport. Ambulances are used to respond to ...

s, etc. The frame plus the body makes a glider (a vehicle without a powertrain).

Final drive

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 British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most rail transport in Great Britain from 1948 to 1997. Originally a trading brand of the Railway Executive of the British Transport Commis ...

)Mann, R. H., ''Diesel Rail-Cars'', Draughtsmens and Allied Technicians Association, 1964, pp 45–50 and RF 11 used in the British Rail Class 03 and British Rail Class 04 diesel shunting locomotives.

Variations

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 the outside of the wheels.

References

External links

New powertrain technologies conference, 27 and 28- March-2007
*http://www.caradvice.com.au/105/car-frame-chassis/

Drivetrain Quiz
*HIL Test Bench (Delphi Motor
Technical Paper: A Closed-Loop Drive-train ModelLearn what a final drive ratio is and how it affects your car
{{Authority control Automotive technologies