BACK TO BASICS - POWERTRAIN What's a powertrain?
From the lowliest hatchback to the sleekest supercar, every motor vehicle has one thing in common: a powertrain. It’s the collection of components—the engine, transmission and driveshaft—that work together to get the vehicle in motion.
A powertrain’s exact design depends on a number of factors, ranging from the type of engine (combustion, electric or hybrid) to its layout on the chassis, and this is what ultimately determines how energy efficient, dynamic and powerful the vehicle is.
Definition: What is a powertrain?
From the initial spark of the ignition to the wheels spinning on their axes, a powertrain's influence can be felt from the front of the vehicle to the back. Put simply, a powertrain is a producer, converter and consumer of energy, all with the aim of getting the vehicle to move. The chain of components involved in the process is as follows:
Engine → Transmission → Flywheel → Driveshaft → Wheels
How an automotive powertrain works
The first step in the powertrain cycle is to switch the engine on to generate energy. This energy then has to be transferred to the wheels, which is where the transmission (consisting of the gearbox and clutch), flywheel and driveshaft come in. Referred to collectively as the ‘drivetrain’, these are the parts that take the energy, slow it down using gear ratios and transmit it as torque—or rotational force—which sets the wheels in motion. The amount of torque produced and the efficiency of the process depend on the vehicle’s transmission type: manual, which requires the driver to manually select the gears; automatic, which automates the gear selection process; semi-automatic, which does away with a clutch but keeps the manual gears; dual-clutch, which is designed for rapid gear shifting; and continuously variable, which provides an optimum gear ratio.
Front-wheel, rear-wheel, four-wheel and beyond
A powertrain can vary significantly depending on whether it is installed in a front-, rear- or four-wheel-drive vehicle. In a front-wheel-drive vehicle, the powertrain converts energy for the front wheels only, while for rear-wheel drive it is the back wheels that are driven by the engine. These two layouts minimize the level of mechanical complexity involved and allows the transmission to be installed in the best location for balanced weight distribution. For four-wheel drive, the powertrain is able to provide torque to all four of the vehicle’s wheels, which offers exceptional control when driving off road, over non-stable surfaces and on steep slopes. Of course, powertrains are not configured for four wheels only. There are also six-, eight- and H-drive variants, which are generally used to power heavy-duty off-road vehicles. In this case, huge amounts of power have to be produced and converted by the powertrain.
Into the future
With the advent of electric cars, the focus in the automotive industry is now on producing innovative, streamlined and environmentally sound electric powertrains that sacrifice none of the power of a conventional variant. As more and more brands continue to pour their resources into drive technologies, the powertrain of the future may look very different to how it appears today.