More unusual configurations
Common cylinder configurations include the straight or inline configuration, the more compact V configuration, and the wider but smoother flat or boxer configuration. Aircraft engines can also adopt a radial configuration, which allows more effective cooling. More unusual configurations such as the H, U, X, and W have also been used.
Multiple cylinder engines have their valve train and crankshaft configured so that pistons are at different parts of their cycle. It is desirable to have the piston's cycles uniformly spaced (this is called even firing) especially in forced induction engines; this reduces torque pulsations21 and makes inline engines with more than 3 cylinders statically balanced in its primary forces. However, some engine configurations require odd firing to achieve better balance than what is possible with even firing. For instance, a 4-stroke I2 engine has better balance when the angle between the crankpins is 180Â° because the pistons move in opposite directions and inertial forces partially cancel, but this gives an odd firing pattern where one cylinder fires 180Â° of crankshaft rotation after the other, then no cylinder fires for 540Â°. With an even firing pattern the pistons would move in unison and the associated forces would add.
Multiple crankshaft configurations do not necessarily need a cylinder head at all because they can instead have a piston at each end of the cylinder called an opposed piston design. Because fuel inlets and outlets are positioned at opposed ends of the cylinder, one can achieve uniflow scavenging, which, as in the four-stroke engine is efficient over a wide range of engine speeds. Thermal efficiency is improved because of a lack of cylinder heads. This design was used in the Junkers Jumo 205 diesel aircraft engine, using two crankshafts at either end of a single bank of cylinders, and most remarkably in the Napier Deltic diesel engines. These used three crankshafts to serve three banks of double-ended cylinders arranged in an equilateral triangle with the crankshafts at the corners. It was also used in single-bank locomotive engines, and is still used in marine propulsion engines and marine auxiliary generators.
Ads on the Internet - is worth a look there cars?
The Internet is full of all kinds of automotive ads. They concern mainly the sale of used cars. Is it worth it to use the online services when looking for a car? It is certainly a very good solution if you do not have stalked the offer on the eye. You have to admit, however, that the majority of websites of the car in a good condition and at a reasonable price "spread" very quickly and to hunt down the network a good car you have to try hard. On the other hand, among the announcements automotive missing SELL they offer us to buy a good car, and really the facts are quite different.
About Alternatives to car use
Established alternatives for some aspects of car use include public transit such as buses, trolleybuses, trains, subways, tramways light rail, cycling, and walking. Car-share arrangements and carpooling are also increasingly popular, in the US and Europe.75 For example, in the US, some car-sharing services have experienced double-digit growth in revenue and membership growth between 2006 and 2007. Services like car sharing offering a residents to "share" a vehicle rather than own a car in already congested neighborhoods.76 Bike-share systems have been tried in some European cities, including Copenhagen and Amsterdam. Similar programs have been experimented with in a number of US Cities.77 Additional individual modes of transport, such as personal rapid transit could serve as an alternative to cars if they prove to be socially accepted.