26-07-2012, 12:16 PM
SPARK PLUG
SPARK PLUG.pptx (Size: 677.47 KB / Downloads: 57)
PRIMARY DETAILS:
A spark plug is usually used in petrol engines but basically they are a type of ignition systems.
It is screwed on the cylinder’s head of a engine.
It is usually designed to withstand a pressure about 35 kilogram per centimeter square and
operate under 10000 to 30000 volts.
Spark plug’s basic work is to ignite the air and fuel mixture in engine.
It can be used in both 2-stoke & 4-stroke engines but of petrol becoz as we know in diesel
engines there is not any type of ignition system required.
Some major spark plug manufacturing companies are Bosch, NGK, Champion , Autolite
or Nippondenso etc.
BOSCH is one of the popular manufacturer in india, its nearest plant to us can be seen in jaipur, sitapura.
Construction of SPARK PLUG
The core insulating assembly is housed in the steel shell assembly.
The lower threaded portion of the shell which has 18 millimeter or 14 millimetre diameter thread on standard plugs has ground electrode welded to it.
The centre electrode is screwed into the insulator at its upper position.
The upper end of the centre electrode is connected to the terminal which communicates with the distributor.
When high voltage is applied,the spark jumps in the small gap which is provided between the lower end of the centre electrode and the ground electrode.
The removal of the sparking plug [easy but be careful]
To remove the plug from the engine, one must first disconnect the insulated lead called the ‘HT lead’ [HT = high tension] from the plug, this is by either a simple pull off cap, or there is a small brass nut which screws onto the top thread of the plug and the HT lead is held on by a brass terminal.
The plug now can be removed from the cylinder head with the aid of a suitable spanner. This spanner not only must be a proper fit on the hexagon part of the plug but ideally it should be a box or socket type which bears on all six sides of the plug.
Even when using the correct box or socket one must be very careful not to tilt the socket over to one side. Damage to the insulator can easily happen if care is not taken. Also watch out for your hands and knuckles as the seven engine bay is not that large!