Hi Gary:
I suggest an extension to your analogy which might cast a different light on
the question. The objective in the lubrification system is not to actually
pass the oil through the pipe, but to keep the pressure up to separate the
bearing surfaces.
Imagine if the pipe you proposed pumping the oil through is softwalled, like a
garden hose. At poiints along the pipe someone has laid a few rocks on the
pipe which are pinching it shut. What you are trying to do with the oil is not
to pump the oil through the pipe but to maintain a pressure that will keep the
pipe as round as possible to keep the walls of the pipe from touching. If you
make the oil too thin it will just lift the individual rocks enough to slip by
but will not give much roundness to the pipe. It would seem that thicker oil
will pass more slowly through the crimped space made by each rock and will
allow the pressure to build up and will lift the rocks.
The analogy is a little inexact (you would have to add in that the rocks have
made small holes in the pipe and that the far end of the pipe is closed), but
it gets the idea across. In this case the rocks are the bearing surfaces
trying to meet and block off the flow. Using very thin oil would be like a
drill-cutting system where you spread lubricant around to keep the surfaces
cool and slippery, but allow the metal-metal contact required for the job. Not
good for a bearing system of course.
There is obviously some sort of maximum viscosity here. A point at which the
resistance of the pipe walls to thick flow exceeeds the ability of the pump to
move the fluid. I assume we are not trying to put honey in the crankcase to
boost the pressure.
That's my Saturday contribution to list confusion for what it's worth.
Cheers,
Mark
________________________________
From: owner-6pack@autox.team.net on behalf of Gary Fluke
Sent: Sat 22/10/2005 2:29 AM
To: Six Pack
Subject: Re: Which Oil Do You Use Anyways?
Gentlemen,
I wonder if seeking a high oil pressure reading is really the goal here.
Oil flow is the requirement. However, the monitoring of our systems is, of
course, done with a pressure gauge. A flow meter would by nature likely be
more expensive and troublesome.
....
Gary
'73
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