Engine Lubrication Systems

[Johann]

Can anybody perhaps explain to me the lubrication system of the typ multi cylinder engine? I see that the radial engines have proper oil pumps. We are talking twins or 4 cylinders, perhaps something to tackle after a basic like the Webster..

 

[Ripcrow]

All more serious engines have a pressurised oil system.Mainly a gear pump and the oil travels through the crank to the big end and mains and through the bearings on the big end to the conrod to the gudgeon pin and also sprays out onto the bottom of the pistons for cooling and the cylinder walls for lubrication..the oil travels via the pushrods to the rocker gear but I'm not sure how the oil gets into the push rods this may only be with hydraulic lifters.over head cams are lubricated by the oil being fed through the bearings into the cam shaft.oil viscosity is very important and will always be better when operating at the right temp.oils function is to keep heat down on bearings and pistons and to provide a surface for the parts to move against so they don't move against each other

 

[Johann]

Thanks Ripcrow for a very thorough explanation, you should give training to the youngsters ! I do however understand how a pressurised system works, just thought there might be a less complicated system to step up to for a next project.

 

[Ripcrow]

Sorry if I went a bit overboard not sure on what you actually required.a splash system would be easy to build but i am not sure if it is very good for overhead gear,you still need oil to the top of the head without flooding it.I would imagine that a piston pump arrangement would be sufficient and easy to build.

 

[t.l.a.r. eng]

If it is a glow engine, the oil in the fuel can lubricate the internals just fine. My 5 cylinder Kinner runs on glow and gets plenty of oil inside, almost too much.
While running, the oil in the fuel migrates past the rings and lubricates all the internal pieces, and the left over drips oil at about 1 drop every three seconds from the crankcase drain. It even lubes the exposed valve guides nicely.
If run on gasoline, and spark, probably needs pressurized oiling. Early engines used pressurized oil that was pumped in a few drops at a time through a needle valve, then thrown out or burned off to maintain the oil level in the troughs for the connecting rod dippers. The crankcase ventilator assisted in the pumping action.
Splash lubrication works well in the small engines as well.
The geared pump probably would be the most reliable.

 

[Johann]

Thanks guys for all the different inputs, I now have a lot of food for thought.