Why is the use of public transport is important especially in big cities?
In particular, many major urban centers there is more and more a problem with the huge traffic jams, especially during rush hours, which is why the authorities of many cities persuade motorists to give up to move your own vehicle and elected public means of transport. Although using public transport for sure we are exposed to the crowd on trams or buses, it should be induced to such exchange. True, motoring fans argue that the use of own car is much more comfortable, but we must bear in mind also that choosing the bus instead of the car contribute to fewer exhaust emissions.
Main article: 4-stroke engine
Diagram showing the operation of a 4-stroke SI engine. Labels:
1 ? Induction
2 ? Compression
3 ? Power
4 ? Exhaust
The top dead center (TDC) of a piston is the position where it is nearest to the valves; bottom dead center (BDC) is the opposite position where it is furthest from them. A stroke is the movement of a piston from TDC to BDC or vice versa together with the associated process. While an engine is in operation the crankshaft rotates continuously at a nearly constant speed. In a 4-stroke ICE each piston experiences 2 strokes per crankshaft revolution in the following order. Starting the description at TDC, these are:78
"ICEV" redirects here. For the form of water ice, see Ice V. For the high speed train, see ICE V.
Diagram of a cylinder as found in 4-stroke gasoline engines.:
C ? crankshaft.
E ? exhaust camshaft.
I ? inlet camshaft.
P ? piston.
R ? connecting rod.
S ? spark plug.
V ? valves. red: exhaust, blue: intake.
W ? cooling water jacket.
gray structure ? engine block.
Diagram describing the ideal combustion cycle by Carnot
An internal combustion engine (ICE) is a heat engine where the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine the expansion of the high-temperature and high-pressure gases produced by combustion apply direct force to some component of the engine. The force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.
The first commercially successful internal combustion engine was created by Ã‰tienne Lenoir around 18591 and the first modern internal combustion engine was created in 1876 by Nikolaus Otto (see Otto engine).
The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine. A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as previously described.12 Firearms are also a form of internal combustion engine.2
Internal combustion engines are quite different from external combustion engines, such as steam or Stirling engines, in which the energy is delivered to a working fluid not consisting of, mixed with, or contaminated by combustion products. Working fluids can be air, hot water, pressurized water or even liquid sodium, heated in a boiler. ICEs are usually powered by energy-dense fuels such as gasoline or diesel, liquids derived from fossil fuels. While there are many stationary applications, most ICEs are used in mobile applications and are the dominant power supply for vehicles such as cars, aircraft, and boats.
Typically an ICE is fed with fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel or fuel oil. There's a growing usage of renewable fuels like biodiesel for compression ignition engines and bioethanol or methanol for spark ignition engines. Hydrogen is sometimes used, and can be made from either fossil fuels or renewable energy.