The common rail system has one high-pressure multiple plunger fuel pump.The fuel is discharged into a manifold or rail which is maintained at high pressure.
From this common rail fuel is supplied to all the injectors in the various cylinders. Between the rail and the injector or injectors for a particular cylinder is a timing valve which determines the timing and extent of fuel delivery.
Spill valves are connected to the manifold or rail to release excess pressure and accumulator bottles which dampen out pump pressure pulses. The injectors in a common rail system are often referred to as fuel valves.
THE DIAGRAM SHOWN IS OF TIMING VALVE
The timing valve in the common rail system is operated by a cam and lever.
When the timing valve is lifted by the cam and lever the high-pressure fuel flows to the injector.
The timing valve operating lever is fixed to a sliding rod which is positioned according to the manœuvring lever setting to provide the correct fuel quantity to the cylinder..