Types of Lubrication System
Liquid lubrication system
Splash system
Semi-pressure system
Full pressure system
Solid lubrication system
Mist lubrication system
Liquid lubrication or wet sump lubrication system :
It use a large capability oil sump at the base of crank chamber from that the oil is drawn by a low-pressure oil pump and delivered to various parts.
Splash system
This system is employed on some small four strokes, stationary engines. During this case the caps on the big ends bearings of connecting rods are provided with scoops which, When the connecting rod is within the lowest position, simply dip into oil troughs and therefore directs the oil through holes within the caps to the big end bearings.
Due to splash of oil it reaches the lower portion of the cylinder walls, crankshaft and other components requiring lubrication. Surplus oil finally flows to the oil sump. Oil level within the troughs is maintained by means of an oil pump that takes oil from sump, through a filter.
Semi-pressure system :
This system could be a combination of splash and pressure systems. It incorporates the advantages of both. In semi-pressure system, oil’s main supply is placed in the base of crank chamber.
Oil is drawn from the lower portion of the sump through a filter and delivered by a gear pump at pressure of about one bar to the main bearings.
The big end bearings are lubricated by spray via nozzles. Therefore oil also lubricates the cams, crankshaft bearings, cylinder walls and timing gears.
Full pressure system :
The oil is drawn from the sump via filter and then pumped by gear pump. The pressure pump at pressure ranging delivers oil from 1.5 to 4 bar.
The oil under pressure is supplied to main bearings of crankshaft.
Camshaft holes drilled through the main crankshafts bearing journals, communicate oil to the big end bearings and also small end bearings through holes drilled in connecting rods.
A pressure gauge is provided to ensure the circulation of the oil to the various parts. A pressure-regulating valve is also placed on the delivery side to prevent excessive pressure.
Solid lubricants or 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 sump is pumped by a sump pump through filters to the storage tank.
Oil from storage tank is pumped to the engine cylinder through oil cooler. Oil pressure may vary from 3 to 8 kgf/cm2.
Dry sump lubrication system is generally adopted for high capacity engines.
Mist lubricants :
This system is used for two stroke cycle engines. Most of these engines are crank charged, crank case lubrication.
These engines are lubricated by adding 2 to 3 per cent lubricating oil within the fuel tank.
The oil and fuel mixture is induced through the carburetor. The gasoline is vaporized and the oil in the form of mist goes to crankcase into the cylinder.
The oil that impinges on the crank case walls lubricates the main and connecting rod bearings, and rest of the oil that passes on the cylinder during charging and scavenging periods, lubricates the piston, piston rings and the cylinder.
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