In our previous articles, we briefly discussed injection systems, first mentioning European standards and then the new Actros trucks. Today, we'll provide much more information and focus on the systems used in trucks. Generally, with trucks, we distinguish between two main types of injection systems: the Common Rail injection system and the Unit-Delivered Fuel Injection (UDF) system.
Common rail injection systems are widely used in Renault (DCI and DXI), Volvo (DXI), MAN (common rail), Scania (HPI and XPI), and other trucks. Each system consists of a high-pressure pump, injectors, a fuel rail, and an engine control unit (ECU), as shown in Figure 1 of this article. In the common rail system, pressure generation and injection are separate functions, meaning that fuel is always available at the pressure required for injection.
Pressure is generated by the high-pressure pump. This pump compresses the fuel and delivers it, via a high-pressure line, to the fuel rail, which acts as a common high-pressure reservoir for all the injectors – hence the name "common rail." The fuel is then distributed to the injectors, which in turn inject fuel into each cylinder. Key advantages include reduced fuel consumption compared to a unit injector system, and increased engine power because the common rail only injects the amount of fuel required by the engine. The main disadvantage is that the common rail is highly sensitive to poor-quality fuel (and our fuel is often heavily polluted in Africa), and because it is a complex system, repair costs are frequently exorbitant. This represents a significant drawback for African users.
Unit pump systems are used in the engines of classic Mercedes Actros, Axor, and Atego trucks (OM501LA, OM502LA, OM457LA, OM906LA, etc.). This is a modular, high-pressure injection system specifically designed for commercial vehicles (trucks). Here, each cylinder is directly supplied by a nearby unit pump, thus reducing fuel pressure lines and resulting in high pressure. Advantages of the unit pump system include greater resistance to poor-quality fuel, lower fuel consumption, and significantly reduced maintenance costs compared to common rail systems. This explains Mercedes-Benz's dominance in the used truck import market in Africa, despite the poor fuel quality. However, it should be noted that newer Mercedes Actros and AROCS trucks (OM47X engines) released since 2011 are now equipped with X-Pulse common rail injection systems (see attached video). For all orders of injectors or individual pumps, regardless of your truck's brand, please feel free to contact us via WhatsApp at +237670355298. If you like this article, please share it as much as possible.
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