Requirement of lubrication: When we rub two surfaces the force required has to overcome the opposite friction force loss between the surfaces. Thus some part of the energy applied in rubbing the surfaces is lost in the form of friction. To overcome the friction we apply certain fluids between the two surfaces which are known as lubricants. Which minimizes the force required to rub the surfaces and some part of the energy lost in friction can be saved.
In an automobile, chemical energy of fuel is converted into mechanical energy by the engine. In engine there are many rubbing surfaces. The friction loss occurs between these surfaces which leads to loss in mechanical energy. To minimize the friction loss between the rubbing surfaces we use some lubricating systems. Hence the main purpose of the lubricating system is to save the mechanical energy. These lubricating systems are designed to provide the proper lubrication to the rubbing surfaces of the engines.
Functions of lubricating oil: A good lubricating oil should perform the following function.
· It reduces the friction between the moving parts.
· It cools the piston so it also acts as a cooling medium.
· It also prevents the leakage of gas between the piston and cylinder because it makes a film of lubricant between them.
· It also reduces the noise between the rubbing surfaces.
Methods of lubrication: Following methods are used for the lubrication of an engine.
· Mist lubrication or petrol lubrication system
· Wet sump lubrication system
· Dry sump lubrication system