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In amotor vehicle, thepowertrain comprises the main components that generatepower and deliver that power to the road surface, water, or air. This includes theengine,transmission,drive shafts,differentials, and the final drive (drive wheels,continuous track as in military tanks or caterpillar tractors,propeller, 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 termpowerplant is casually used to refer to the engine or, less often, the entire powertrain.
A motor vehicle'sdriveline ordrivetrain consists of the parts of the powertrain excluding the engine. It is the portion of a vehicle, after theprime mover, that changes depending on whether a vehicle isfront-wheel,rear-wheel, orfour-wheel drive, or less-commonsix-wheel oreight-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 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. theaxle. In hybrid powertrains thetorque 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 fordiesel engines involves the following:exhaust gas recirculation (EGR), and advanced combustion.Spark ignition engine development include:fuel injection, including thegasoline direct injection variant, as well as improvingvolumetric efficiency by usingmulti-valves per cylinder,variable valve timing,variable length intake manifolds, andturbocharging. Changes also include new fuel qualities (nosulphur oraromates) 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) orgas to liquid (GTL)).[1]
BEVs,FCEVs andPHEV powertrains are expected to reach cost parity withICE powertrains in 2025.[2]
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.
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 surfaceflatness,waviness,roughness, andporosity.Quality control over these parameters is achieved throughmetrology technology applied to all of the steps in powertrain manufacturing processes.
In automotive manufacturing, theframe plus the "running gear" makes thechassis.
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 thevehicle. Commercial vehicle manufacturers may have "chassis only" and "cowl and chassis" versions that can be outfitted with specialized bodies. These includebuses,motor homes,fire engines,ambulances, etc.
The frame plus the body makes aglider (a vehicle without a powertrain).
The final drive is the last in the set of components which delivers torque to thedrive wheels. In a road vehicle, it incorporates thedifferential. In a railway vehicle, it sometimes incorporates the reversing gear. Examples include theSelf-Changing Gears RF 28 (used in manyfirst-generation diesel multiple units ofBritish Railways)[3] and RF 11 used in theBritish Rail Class 03 andBritish 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 the outside of the wheels.
| Code | Description | Use | Graphic |
|---|---|---|---|
| RWD | Rear Wheel Drive | Small Van |  |
| 4WD | Four Wheel Drive AKA 4x4 | Pick Up Truck |  |
| FWD | Front Wheel Drive | Van, Where Weight is desired over front wheels |  |
| DWD | Dual Wheel Drive (Dually) | Extra load Capacity is required to a 4WD | _Dual_Rear_Wheel.jpg) |
| 6X4 | A 6×4 or six-by-four is a vehicle with three axles, with a drivetrain delivering power to two wheel ends on two of them. It is a form of four-wheel drive but not one of all-wheel drive. | Classic Truck |  |
| 6x6 | 6X6, a standard class of medium-duty trucks | Classic Mil spec |  |
| 6X2 - Rear Lift | In its purest form, a 6x2 chassis configuration is a three-axle tractor with power going to just one of the tandem rear axles. Put another way, only two of the six wheel positions are powered. | Where Trucks need a shorter turn radius and at times don't need the extra axle to improve fuel consumption (the rear wheels can be lifted off the ground when not needed) |  |
| 6x2 Mid Lift | three-axle tractor with power going to just one of the tandem rear axles. | The middle axle is able to be lifted, typical use is where max weight is given to cargo (such as fuel tankers), sometimes the middle axle as smaller wheels and tyres |  |
| 8X4 | 8X4 means that the Truck has four axles, two of which are driving axles. | Typical use is a Tipper Truck, which has on and off-road requirements. |  |
| 8X8 | 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 (that is, to receive power from the engine) simultaneously. | Military or extremely high-load and off-road capability is required. |  |
| 6x6 | Six-wheel drive (6WD or 6×6) is an all-wheel drive drivetrain configuration of three axles with at least two wheels on each axle capable of being driven simultaneously by the vehicle's engine. | Typical Small to medium Mining Truck or Military use. |  |
| Half-Track | Ahalf-track is a civilian ormilitary vehicle with regular wheels at the front for steering andcontinuous tracks at the back to propel the vehicle and carry most of the load. The purpose of this combination is to produce avehicle with thecross-country capabilities of atank and thehandling of awheeled vehicle. | Typical WW2 era not main streamed produced today. |  |
| Tracked | Continuous track ortracked treads are a system ofvehicle propulsion used intracked 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 weight of the vehicle better than steel or rubber tyres on an equivalent vehicle, enabling continuous tracked vehicles to traverse soft ground with less likelihood of becoming stuck due to sinking. | Tractors, Tanks, Excavators, and Dozers. |  |
| Electric | Anelectric vehicle (EV) is a vehicle that uses one or moreelectric motors for propulsion. It can be powered by acollector system, with electricity from extravehicular sources, or it can be powered autonomously by abattery (sometimes charged bysolar panels, or by convertingfuel to electricity usingfuel cells or agenerator). EVs include but are not limited toroad andrail vehicles, and broadly can also includeelectric boat andunderwater vessels (submersibles, and technically alsodiesel- andturbo-electricsubmarines),electric aircraft andelectric spacecraft. | In this power train the EV is powered by a large onboard engine, and has the typical application of very heavy-duty mining truck. |  |
