Lubricating Systems

The lubrication system is subdivided mainly into three groups.

1. Charge Lubrication System. This is the most simplest method of lubrication and does not require oil-filter and oil pump. In this system, the lubricating oil is pre-mixed with the petrol therefore the fuel carries the lubricating oil in the cylinder which helps for lubricating the piston and cylinder. Most of the oil burns with the fuel due to high temperature and burnt oil is carried wi:h the exhaust gases. The lubricating oil cannot be recovered in this system.

This type of lubrication is generally used for two stroke spark ignition engines of scooter and motor cycle. The quantity of lubricating oil mixed with the petrol is 3 to 6% of petrol.

The advantages of this system are listed below

I. It does not require seperate lubricating system so it is most economical.

2. There is no risk of failure of lubrication system.

3. The lubricating oil supplied is regulated at various loads and speeds by the increased fuel flow.

The carbon deposits due to the burning of the oil on the spark plug and on other pirts and non-recover of the oil used are the main disadvantages of this system.

2. Wet Sump Lubrication System. This system employes a large capacity oil sump at the base of crank case and oil is passed to the different parts with the help of pressure pump. The oil returns back to the sump after serving the purpose. The oil under-pressure is circulated generally through the different parts. This system is further subdivided into splash lubrication and pressure lubrication.

3. Dry Sump Lubrication System. In this system, the oil from the sump is carried to a separate storage tank outside the engine cylinder block. The oil from the sump is pumped through filter into the storage tank with the help of a pump. The oil from the storage tank is further pumped by the another pump to the cylinder through oil cooler. This is generally used for high capacity engines. The pressure of the oil used in this system lies between 3 to 8 bar.