Technical Paper
Lubricant as a Construction Element in the VDT Push-Belt CVT System
1993-10-01
932848
Since 1987, Van Doorne's Transmissie (VDT) BV has produced a steel belt for continuously variable transmission (CVT) applications. To date, over 750,000 vehicles have been equipped with the system, and belt reliability has proved to be very high. During the early stages of transmission production, an intermittent lubricant-related noise problem was encountered. This paper describes the steps taken to isolate the noise source and eliminate it. The noise, commonly called the “scratch phenomenon,” manifests itself as a transfer-gear rattle under slow-speed, light-load conditions. Initial investigation revealed that the scratch phenomenon could be avoided by using an alternative transmission fluid (1). Experimental work conducted by Lubrizol and VDT to understand the mechanism behind the problem: Established a relationship between the occurrence of the scratch phenomenon and the stick-slip properties of the belt-material/lubricant combination.
