The term "common rail" refers to a certain type of fuel direct injection system. The pressure generation and fuel injection components are separate from one another, with pressure being generated continuously by an independent pump that can be fitted anywhere on the engine. This pressure is stored in the distributor rail, which is better known as the "common rail". Lines connect all the cylinder injectors to the common rail in parallel, ensuring that all injectors have an uninterrupted supply of constant pressure. The injection quantity and timing are controlled using solenoid valves at the individual injectors.