Quote:
Originally Posted by sickpuppy318
my old '88 toyota had a internal gear "gearoter" oil pump, and being positive displacement, had output pressure directly proportional to engine speed. So while engine loads decrease with RPM, so did oil pressure. It lugged a lot more than my mazda does now....
now after reading these articles, i realize that the lugging "jerk" at low RPM/high throttle is litterally the crank being thrown into the side of the bearing. ...not good.
OK, so now i guess i'll feather it past the "lug line", but have more confidence lugging around below it. slow and easy, not slow and WOT.
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sickpuppy,I think your's was the first use of the term "jerk",which I understand as an "instantaneous acceleration." Under some of the extreme "lugging" scenarios mentioned,I understand that if jerk occurs,the bearing journal can actually displace the oil film,achieving "high-point",where there exists momentary metal-to-metal contact between the journal and babbit material.Instantaneous friction-welding and then fracture-release can occur,and this is basically the beginning of the end for both surfaces.I have been told that the switch to automatic transmissions for Diesels,has happened in part do to broken crankshafts due to "jerk",when operators let rpm's drop too low.Evidently,the torque-converter on an automatic will stall before rpm's can drop to a level where jerk would occur,protecting the crank.