Main article: Diesel cycle
P-v Diagram for the Ideal Diesel cycle. The cycle follows the numbers 1?4 in clockwise direction.
Most truck and automotive diesel engines use a cycle reminiscent of a four-stroke cycle, but with a compression heating ignition system, rather than needing a separate ignition system. This variation is called the diesel cycle. In the diesel cycle, diesel fuel is injected directly into the cylinder so that combustion occurs at constant pressure, as the piston moves.
Otto cycle: Otto cycle is the typical cycle for most of the cars internal combustion engines, that work using gasoline as a fuel. Otto cycle is exactly the same one that was described for the four-stroke engine. It consists of the same four major steps: Intake, compression, ignition and exhaust.
PV diagram for Otto cycle On the PV-diagram, 1?2: Intake: suction stroke 2?3: Isentropic Compression stroke 3?4: Heat addition stroke 4?5: Exhaust stroke (Isentropic expansion) 5?2: Heat rejection The distance between points 1?2 is the stroke of the engine. By dividing V2/V1, we get: r, where r is called the compression ratio of the engine.
Car - etymology
The word "car" is believed to originate from the Latin word carrus or carrum ("wheeled vehicle"), or the Middle English word carre (meaning cart, from Old North French). In turn, these originated from the Gaulish word karros (a Gallic chariot). The Gaulish language was a branch of the Brythoic language which also used the word Karr; the Brythonig language evolved into Welsh (and Gaelic) where 'Car llusg' (a drag cart or sledge) and 'car rhyfel' (war chariot) still survive.1112 It originally referred to any wheeled horse-drawn vehicle, such as a cart, carriage, or wagon.1314 "Motor car" is attested from 1895, and is the usual formal name for cars in British English.3 "Autocar" is a variant that is also attested from 1895, but that is now considered archaic. It literally means "self-propelled car".15 The term "horseless carriage" was used by some to refer to the first cars at the time that they were being built, and is attested from 1895.16
The word "automobile" is a classical compound derived from the Ancient Greek word autós (?????), meaning "self", and the Latin word mobilis, meaning "movable". It entered the English language from French, and was first adopted by the Automobile Club of Great Britain in 1897.17 Over time, the word "automobile" fell out of favour in Britain, and was replaced by "motor car". It remains a chiefly North American usage.18 An abbreviated form, "auto", was formerly a common way to refer to cars in English, but is now considered old-fashioned. The word is still used in some compound formations in American English, like "auto industry" and "auto mechanic".
There is no doubt that the most popular is the driving enabling management of passenger cars. Today, few who do not already have such a document. But there are many other categories of driving licenses, which entitle to drive other vehicles. Such courses are also conducted in the centers involved in the training of drivers of passenger cars. Why go for a license in a different category? Primarily related to an increase in opportunities. Those fascinated by motorcycles are not allowed to drive them without holding a driving license in the category. The same is true for buses and big trucks and other vehicles.