How lubrication in 4 stroke engine Takes place ? It is done either by splash lubrication or Pressure lubrication system. In this article, I will describe step by step so that you can understand Lubrication in 4 four stroke engine with diagram auxiliary engine easily.

Try to understand the layout Lubricating system of 4 stroke or Auxiliary engine. IT help you in visualising all the parts and how oil moves from sump to all parts and come back to sump of the engine.

Layout of Lubricating system of 4 stroke or Auxiliary engine

The lubricating system used in four stroke engines are based on wet sump lubrication. A pump called lube oil pump run with conjunction of engine used lubricating oil to lubricate all the parts of engine in closed system. The lube oil sump used for lubrication of parts like main bearings. gudgeon pin, cylinder liner etc. also used for piston cooling. I will explain the cooling of piston of four stroke engine later.

Layout of Four stroke engine lubricating systems

The lube oil draws the lube oil from sump of the engine and pass through primary filter. after primary filter lube oil passes to the cooler which is used for cooling the lube. After that it passes to the main filter and branches to two sections. One line go to main bearings and through hole in the crankshaft it go to crank pin for lubrication. After crankpin it passes through hole inside crankshaft and reaches to piston pin or gudgeon pin lubrication. Through the end of gudgeon pin lube oil comes go to cylinders. Scrapper oil did the work of lubricating cylinder. Excess oil scraps off to sump by scraping piston rings. Another line go for lubrication of gear system of all the pump connected to crankshafts. The pump connected are lube oil pump, jacket pump, governor, rocker arm pump, fuel oil pump etc.

This is brief description of lubricating system. Now let us see full description of all parts …

The above see that lubrication system is pressure type lubrication system. Now we see all the parts which is used for lubrication. The main parts which is lubricated are :-

  • Main Bearings
  • Crank Pin or Bottom end bearings
  • Top end bearings or Gudgeon pin Or piston pin
  • Cylinder liner lubrication
  • Camshaft
  • Crankshaft drive
  • Governor drive
  • Turbocharger
  • Rocker arm system

1.Main Bearings : -Connecting rod is connected to the main bearings. Main bearings faces high load. IT is lubricated through hole provided to the main bearings. Lube oil from Filters pass to the main bearings. lube oil pass through pressure.

2.Crank pin bearings : – Crank pin bearings connect the crankshaft to the crank pin. This is used for converting reciprocating motion into rotary motion or vice-versa. Through inner hole in the crankshaft lube oil from main bearing passes to the crank pin bearings.

3.Gudgeon pin or piston pin :- There is a passage provide in the crankshaft. Lube oil reaches to gudgeon pin from crank pin through hole provided in the crankshaft.

4.Cylinder lubrication :- Oil from gudgeon pin passes to cylinder through end of Piston pin. The scraper rings scraps oil to top of liner for lubrication and excess oil scraps back to the sump.

5.camshaft :-Camshaft drive did the work of driving driving driven shaft of all the pumps connected to the engine. There is a nozzle provide on its top. Lube oil continuously pass lube oil to gear for proper lubrication.

6.Crankshaft drive :-Camshaft drive also provided with a nozzle on the top for lubrication of gear mesh.

7.Governor :-Governor works their function by gear meshing mechanism. it also connected with drive. The lube oil pass to the gear mesh through piping system.

8. Turbocharger :- In some Engine Lubrication of bearings of shaft done with the help of Same lube oil. One line branch and did the work of lubricating both bearing i.e turbine side bearings and blower side bearings.

In some engine splash lubrication done. sump is provided below the bearings. As the bearings rotate , lube oil dip help in lubricating.

In last we will understand lubrication of turbocharger.

9.Rocker Arm system :- As we know rocker arm used to open or close the inlet and outlet valve of the auxiliary engine. Here, lubrication also provided. Keep in mind, some engine, lubrication of rocker arm done with the same lube oil pump. after filter one line go for lubrication of rocker arm.

In daihatsu diesel engine, There is A special pump rocker arm pump ( Internal gear pump ) Provided for lubrication of rocker arm.

Line diagram of rocker arm system

Lubrication of rocker arm system are explained below :-

The Rocker arm lube oil tank >>> torchoid pump ( with safety valve ) >>> lube oil filter >>> Supply oil main pipe >>> rocker arm shaft bush >>> rocker arm end >>> returning main pipe >>> rocker arm lube oil tank

Note :- With line of oil which lubricate the rocker arm being made independent and seprate from the other line for system oil. The system oil is protected from earlier deterioration. Since, the oil which lubricates the rocker arm is opt to become dirty because of exhaust gas, external dust, fuel oil being mixed into it.

Note :- However some oil returns directly to the rocker arm lube oil tank from the oil pressure relief valve provided at the end of the supply oil main pipe.

Line Diagram of stroke engine lubricating system

Lubrication of four stroke engine

Lubricating oil from the oil sump tank >>> Primer filter >>> The lubricating oil pump >>> lubricating oil cooler >>> lubricating oil pressure relief valve >>> lubricating oil filter >>> lubricating oil main pipe.

Now lubricating oil main pipe branched into two lines :-

1. The one line lubricates the main bearing shell, crank pin bearing shell and piston pin bush.

2. While the other line lubricates the cam shaft bearing shell, tappet surroundings, governor and idle gear bush.

Then they will come together to drop into the sole plate. In some modes of engines, the valve rocker arm is lubricated in this circulation.

Lubricating Oil pump :- lubricating oil pump used here is external gear pump. It is located at the front of the engine and is powered by the crankshaft via a coupling or a gear wheel.

Note :- In some engine splash lubrication system is used. In this lubrication system, lube oil is submerged partially. when crankshaft rotates, it splash the lube oil on surfaces.

How piston cooling is done in 4 stroke engine ?

As piston get hot too much because it is directly in contact with combustion. So, we need to to cool it working properly. Otherwise failure of Piston. Piston cooling is done by the Nozzle provided near the under space of piston.

This is all about lubrication of 4 stroke engine or auxiliary engine.

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