Diesel - a Brief description

   For your information the following is a very brief, everyday description of the different types of diesel equipment.
DIESELS DON'T USE SPARK PLUGS
Diesel engines of any type work because diesel fuel is injected into a cylinder of highly compressed air. Because the air is compressed it is very hot ; the fuel ignites forcing the piston into the cylinder and turning the crankshaft.
INJECTORS SPRAY FUEL INTO THE ENGINE 
Diesel fuel has to be atomised (turned to mist or microscopic droplets) the injectors are designed to make this happen.

ROTARY VS COMMON RAIL
Diesel is broadly divided into Rotary diesel and Common Rail diesel.

ROTARY - MECHANICALLY CONTROLLED
ROTARY DIESEL. This is diesel equipment which we now call early diesel.
It generally has little or no electronic control and has been replaced in passenger cars by common rail.
A rotary diesel engine typically has a distribution pump and injectors. The pump is timed to the engine so it sends fuel under pressure to each injector at the correct time in the engine's combustion sequence.

ROTARY IS LOW PRESSURE
The pressure at each injector is somewhere in the region of 150 bar. Typically a rotary diesel pump has a solenoid which allows the driver to cut off the supply of fuel and stop the engine; without this the engine will continue to run as long as it has a supply of fuel!

DIRECT AND INDIRECT INJECTION
Rotary diesel can be divided into ''direct' and 'indirect' injection. Direct injection engines are designed for the fuel to be injected directly into the cylinder, typically into a bowl recess in the crown of the piston. With indirect injection the fuel ignites in a separate combustion chamber recessed into the cylinder head. The rate of combustion is slowed down and the engine is generally quieter and less stressed than direct injection. When starting indirect engines generally require glowplugs to warm the fuel until the engine is running and getting warm. Later Ford Transit 8 valve diesel engines (up to c.1999) are of the direct injection type and have a characteristically noisy diesel sound.


COMMON RAIL - A NEW TYPE OF DIESEL?
Common rail engines don’t need time to heat up as well as being quieter and cleaner
Because common rail diesel injection is electronically controlled the timing of the injection is more accurate. Additionally because the fuel is under much higher pressure it atomises more effieciently which in turn makes the engine run quieter and with less vibration.