Såg lite info här: http://www.crank-scrapers.com/What%20is%20a%20crank-scraper.html
"Is a windage tray the same as a crank scraper?
No, a windage tray serves a different but related basic function. It is present to act as a physical barrier between the rotating assembly and the sump reservoir. A crank scraper actively removes excess oil and returns it to the sump. Some windage trays do have scraper technology built into them but even then a dedicated scraper will approach the moving parts much more closely."