U ovom radu objašnjava se princip rada i radni ciklus diesel motora za dvotaktne i četverotaktne diesel motore. Detaljno se prikazuje princip rada svakog od njih, njihova primjena, prednosti i nedostatci. Jedna od najvažnijih stavki kod diesel motora je ubrizgavanje goriva. U radu prikazujemo dvije vrste ubrizgavanja, a to su direktno i indirektno ubrizgavanje. Usporedbom direktnog i indirektnog sustava ubrizgavanja zaključujemo da je indirektan sustav stvar prošlosti, dok sustav direktnog ubrizgavanja ima svoju budućnost. Za pokretanje diesel motora, osim sustava za ubrizgavanje, potreban nam je uređaj za hladni start, regulator sustava za ubrizgavanje i visokotlačna pumpa. Da bi diesel motor pravilno radio potrebno je sve sustave vezane za ubrizgavanje i regulaciju međusobno uskladiti, u suprotnom dolazi do oštećenja motora, emisije štetnih plinova i kvarova. Osnovna svrha visokotlačne pumpe je stvaranje pritiska goriva pri samome ubrizgavanju u cilindar. Postoji više vrsta visokotlačnih pumpi, ali svrha im je ista. U budućnosti će se najčešće upotrebljavati motori s prednabijanjem. Osnovna svrha prednabijanja je povećanje snage i okretnog momenta, a to se postiže nabijanjem velike količine zraka u cilindar. Prednabijanje motora je moguće kombinacijom usisnih cijevi, ali i pomoću vanjskog turbopuhala. Vanjsko nabijanje je moguće pomoću turbopunjača i superpunjača. Detaljnom obradom turbopunjač se pokazao mnogo pouzdanijim i kvalitetnijim od superpunjača. Kombinacijom oba punjača pokrivaju se njihovi pojedinačni nedostaci, a pritom se postiže najveća snaga.

In this paper the cycle of a two-stroke and three-stroke diesel engines is described. The work principle, their application, advantages and disadvantages are discussed in detail. One of the most important points with diesel engines is the fuel injection, which can be either direct or indirect. Comparing the two we can safely conclude that the indirect system is a part of history while the direct fuel injection system has great potential for the future use and development. To start up the diesel engine, besides the fuel injection, we need a Cold Start Device (CDC), injection system regulator and a high pressure pump. In order for the engine to function properly, regulation and injection systems have to be harmonized, otherwise engine damage, toxic fuel emission and motor malfunction may occur. The purpose of the high pressure pumps is the creation of the fuel pressure during its injection into cylinder. There are multiple types of high pressure pumps but their purpose is the same. It is taught that in the future engines with forced induction will be most commonly used. The basic purpose of forced induction the increase in power and revolving momentum which is accomplished by injecting a large amount of air into cylinders. Forced induction is made possible by using a combination of intake manifolds and an external turbocharger. External forced induction is created by using a turbocharger and an engine superplug. In day to day use a turbocharger was shown to be much more reliable than the superplug or supercharger. By combining the two we can mask their individual drawbacks and reach the highest power possible.