Quote:
Originally Posted by bigred5765
i was alway told pack is the Resistance of the oil to move through the hole IE the piston is trying to compress the oil,
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Yes, the first part is correct, the second part I don't agree with.
also one thing I don't agree with is that the smaller holes make the oil flow faster if compared with the same overall hole area but less holes.
If the overall area of the holes are the same, the speed which the oil flows must be the same...?
I think the pack comes because with the smaller holes, there isn't any oil that ISN'T affected by turbulence from the edge of the hole.
for example, if turbulence happens within 0.5mm of the edge of the hole edge(when at piston speed X), in 1mm holes, ALL the flowing oil will be affected by turbulance from the edge of the hole.
If you had 2mm holes that had the same overall area, there would be a part in the middle of the hole where the oil isn't affected by turbulance meaning this part oil still flows efficiently, which means you get less 'pack'
because as speed increases turbulence happens further and further away from the edge of the hole, the 2mm holes will eventually 'fully pack up' just at a much faster piston speed than the 1mm holes.
All of this is how I understand the physics to work, however, its never as perfectly uniform as the theory. there are so many factors involved but that's how I think it works.
throw in hole shapes, rounded edges, taper pistons, angled holes multi-size holes etc etc and you can spend YEARS testing this stuff out.
... and probably end up where you started!