Good point. It will only be as good as it is clean.
I recently saw an example on a “Wired Science” episode that put the effect of a lot of people doing a little really adding up, nothing to do with automibles. This man from Guatamala was involved in scanning books in order to store them in digital form. The computer was having trouble with many odd characters. Now comes the connection, do you know what I mean when I speak of a “capalla”? These are the distorted numbers and letters you deciper so that it is clear you are a human and not a machine. The guy figured that more man hours had been used figuring out capalla’s than building the Panama Canal(some 200 million man hours for the capallas not the canal). The responses given by people figuring out capallas were used to give the computer a better guess at what the letter was(I have paraphrased the process), a very good use of otherwise wasted use of the human brain.
It will be some time before it’s proven, to be sure!
Just the rambling of a tired old grease monkey here, but if an engine were equipped with decompression valves and at cold start up the engine were spun over in ‘freewheeling’ mode until oil pressure was up and all moving parts flooded with oil start up wear would be significantly reduced. It is my observation that cold start up is the worst wear situation on an engine in normal service.
Anyone remember “ARCO Graphite” motor oil?? “Nano” is just the new buzz-word to sell product…
Most of the “friction” in an IC engine is viscosity drag, not metal to metal contact…
I agree with you on the cold start situation. But wouldn’t the same thing be happening if there was compression going on or not?? Isn’t it the fact that there is metal to metal contact happening because of no oil at start up that causes the wear? I dont see what difference it would make.
The same wouldn’t really be happening. The detonation of combustion creates large loads on the rings, cylinder walls, wrist pins, connecting rod bearings, and crankshaft bearings that would not be created in “freewheeling”. Much of the wear, and damage should there be any, in these key areas is detonation-driven.
Eliminating combustion alone until oil pressure is up would seem an obvious way to reduce wear. Eliminating compression also would be a bit better.
Piston compression rings are designed to press against the walls when loaded from above. Crankshafts also, in fact, deflect from combustion forces pushing laterally on them through the connecting rods, and the added loads on connecting rod bearings and wristpins is obvious.
You want it to last forever?? You have to get with the program…Pre-lube electric pumps…Get that “Wet Start” every time !!
What makes you think that the bearings are dry until there is oil pressure?
Have you ever done that science experiment where you put two pieces of flat glass together with water between them and you could not pull the pieces of glass apart because of the surface tension of the water film in between those pieces of glass?
The exact same thing happens in the bearing clearence with oil, in fact, when you disassemble engines that have sat not running for months, even years, and you take the rod and main bearings apart, you find that there is oil in the clearance and it sometimes makes it difficult to pull the bearing shells apart.
The hydrodynamic oil wedge that supports the turning shaft happens almost the instant the shaft starts turning, even without oil pressure. The purpose of oil pressure is to replace hot oil in the bearing with cold oil as the engine runs, not to support the shaft.
Dry bearings. No. The Model T engine used splashing for lubrication. All early internal combustion engines used the waste method. But they had compression ratios of 4 to 1 and maximum RPM was well under 2,000. When a high compression engine starts on the first revolution and immediately revs to 2,000 how often are the bearings spun dry before the oil pressure has purged the air and floods the bearings? And how many revolutions will be turned at 2,000 RPM before the cylinder walls are washed down? But like I said, I’m just an old grease monkey
Excellent point. While my earlier reply was only intended to address DfromSD’s specific question, you make a good point that the critical wear surfaces retain oil between their corrosponding wear surfaces anyway.
I would respectfully disagree with the comment about the purpose of oil pressure in the bearings, however. The primary purpose is to maintain a pressurized barrier. Removal of heat and parts washing are secondary (but important) functions.
I wonder if nanoparticles suspended in a less viscous oil would provide acceptable lubrication and less viscosity drag?
Myth Busters went from 26mpg to 29mpg with a dimpled car.
I think the auto companies are all over that one.
I have a lot of experience with large electric motors and many of the larger ones use poured babbit bearings instead of ball or roller bearings, in fact, I have even poured and machined babbit bearings for these large electric motors.
Some of these are pressure oiled but mostly they are ring oiled, a brass hoop rolls on the top of the shaft and dips in an oil sump below the bearing, the hoop wet with oil keeps the bearing oiled.
Even when sitting for a long time, plenty of time for oil to drain out, you can turn the shaft and the shaft is “floating” before the shaft even makes a half of a turn and once broken loose, the floating shaft spins almost effortlessly, even though the rotor that the bearings are supporting weighs tons.
I don’t have to wait for the oiling ring to deliver oil to the bearing before it spins freely.
So, I still think that the 1.5 to 2 thousanths of an inch oil clearence acts like a capillary tube and stays filled with oil when the bearing is still and the oil pump isn’t delivering any oil.
If it was the oil pump’s oil pressure that floated the shaft, you would need oil pressure in the order of 10,000 psi in order to support the peak loads of an auto engine on that tiny amount of surface area.
I’m certainly not a mechanical engineer, but there would seem to be great deal of difference in the load characteristics of an electric motor armature shaft and the internals of an engine. My first question regarding the multi ton armature bearing is how large is it?