What is Mean by Power Train of Automobile ?

If the chassis is the skeleton, the powertrain is the musculature system. The powertrain encompasses every component that converts the engine’s power into movement.It consists of various groupings of engine, clutch, gearbox ,transmission, the driveshaft, differentials, axles; basically anything from the engine through to the rotating wheels.

Powertrain management is a function of the electronic control module (ECM). Depending on the car, the ECM may also be called the powertrain control module (PCM). The ECM or PCM gets inputs from sensors and sends outputs via other sensors.

The basic power flow, meaning the way in which energy is passed through the system, is as follows:
As fuel and air mixture is ignited above the pistons, they push on connecting rods which are on cranks, just like a cyclists legs driving pedals.

This makes the crankshaft rotate. Power is passed through the clutch and then through a gearbox. The output of the gearbox is linked to the final drive. This then applies the power to the front wheels through drive shafts. These shafts have joints so they can move with the steering and suspension.

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 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 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)).