The common rail system

  • Product information

    Common rail systems have a modular design. Each system consists of a high-pressure pump, injectors, a rail, and an electronic control unit.

    Mode of operation

    With conventional diesel injection systems, the fuel pressure has to be generated individually for each injection. With the common rail system, however, pressure generation and injection are separate, meaning that the fuel is constantly available at the required pressure for injection. Pressure generation takes place in the high-pressure pump. The pump compresses the fuel and feeds it via a high-pressure pipe to the inlet of the rail, which acts as a shared high-pressure reservoir for all injectors – hence the name "common rail". From there, the fuel is distributed to the individual injectors, which inject it into the cylinder's combustion chamber.

    Broad range of solutions

    Bosch offers common rail systems for all vehicle models from microcars to heavy luxury limousines. The high-pressure pumps operate at pressures between 1,100 and 2,200 bar. Systems with individual pumps are also available (plug-in pumps). The injectors use either solenoid valve or Piezo technology.


    • Efficient fuel injection due to extremely short spraying distances and multiple injection
    • High engine power and smooth running with low consumption and emissions
    • Can be used with all vehicle models due to modular design