A differential pressure valve 6 is provided in an engine lubricating system which spills lubricating oil into a bypass line 5b bypassing a lubricating oil heat exchanger 7. Connected downstream of the differential pressure valve 6, is a pressure-maintaining valve 10, which holds the oil pressure approximately...http://www.google.com/patents/US5220892?utm_source=gb-gplus-sharePatent US5220892 - Lubricating system
