Intake, induction or suction: The intake valves are open as a result of the cam lobe pressing down on the valve stem. The piston moves downward increasing the volume of the combustion chamber and allowing air to enter in the case of a CI engine or an air fuel mix in the case of SI engines that do not use direct injection. The air or air-fuel mixture is called the charge in any case.
Compression: In this stroke, both valves are closed and the piston moves upward reducing the combustion chamber volume which reaches its minimum when the piston is at TDC. The piston performs work on the charge as it is being compressed; as a result its pressure, temperature and density increase; an approximation to this behavior is provided by the ideal gas law. Just before the piston reaches TDC, ignition begins. In the case of a SI engine, the spark plug receives a high voltage pulse that generates the spark which gives it its name and ignites the charge. In the case of a CI engine the fuel injector quickly injects fuel into the combustion chamber as a spray; the fuel ignites due to the high temperature.
Power or working stroke: The pressure of the combustion gases pushes the piston downward, generating more work than it required to compress the charge. Complementary to the compression stroke, the combustion gases expand and as a result their temperature, pressure and density decreases. When the piston is near to BDC the exhaust valve opens. The combustion gases expand irreversibly due to the leftover pressure?in excess of back pressure, the gauge pressure on the exhaust port?; this is called the blowdown.
Exhaust: The exhaust valve remains open while the piston moves upward expelling the combustion gases. For naturally aspirated engines a small part of the combustion gases may remain in the cylinder during normal operation because the piston does not close the combustion chamber completely; these gases dissolve in the next charge. At the end of this stroke, the exhaust valve closes, the intake valve opens, and the sequence repeats in the next cycle. The intake valve may open before the exhaust valve closes to allow better scavenging.
While many people mistakenly believe that the pirates road only directing the car passenger or a motorcycle, more often unfortunately, can be seen that also other vehicles moving at extremely high speeds, especially on highways that are a little better than the standard highway . Many speeders, not at all applicable to the rules of the road that drivers of large trucks. They often mistakenly believe that the bigger the car on the road, the greater is the priority in traffic and forcing the other participants in the traffic, which can have very dangerous consequences. Going on a long trip, it must therefore be very careful with this kind of riding companions.
Automobile bit differently
The most popular when it comes to automotive, enjoy, of course, cars and motorcycles. With the increasing number of drivers also increases the number of such vehicles on our roads. However, in everyday life may be useful also other machines connected to the most popular vehicles. A good example can be here the equipment needed in agriculture, which is often not independent of the vehicle. Many agricultural machines and used in the construction industry we can associate, for example, a tractor suitable brand, which will certainly be of interest holders of such a vehicle. Of course, there is also a lot of self-propelled agricultural machines, but they are often very expensive.