CAR: Powertrain

Scale model of the powertrain of a Moto Guzzi V-8 motorcycle

In a motor vehicle, the term powertrain or powerplant refers to the group of components that generate power and deliver it to the road surface, water, or air. This includes the engine, transmission, driveshafts, differentials, and the final drive (drive wheels, continuous track like with tanks or Caterpillar tractors, propeller, etc.). Sometimes "powertrain" is used to refer to simply the engine and transmission, including the other components only if they are integral to the transmission. In a carriage or wagon, running gear designates the wheels and axles in distinction from the body.
A motor vehicle's driveline consists of the parts of the drivetrain excluding the engine and transmission. It is the portion of a vehicle, after the transmission, that changes depending on whether a vehicle is front-wheel drive, rear-wheel drive, or four-wheel drive.
In a wider sense, the power-train includes all of its 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

Powertrain development for diesel engines involves the following trends: modular injection, electronic valve control (EVC), low pressure exhaust gas recirculation (EGR), and advanced combustion. Spark ignition technology has focused on de-throttling (in part load where the low efficiency of Otto engines is defined) and downsizing (lower displacement, EVC).^[1]
Attention to new fuel qualities (no sulphur and aromates) allow new combustion concepts. These promise to combine clean combustion with high efficiency. So-called "combined combustion systems" (CCV) (Volkswagen, 2003) or "diesotto" cycles (Mercedes-Benz) are based on synthetic fuels (synthetic diesel, biomass to liquid (BTL) or gas to liquid (GTL)).^[2]

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. Quality control over these parameters is achieved through metrology technology applied to all of the steps in powertrain manufacturing processes.

Frames and powertrains

In automotive manufacturing, the frame plus the "running gear" (powertrain) 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 the body makes a glider (a vehicle without a drivetrain).