The circulation-type foaming test method of lubricating oils to simulate the foaming characteristics of ATF in the automatic transmission

摘要

ASTM D 892 "Standard Test Method for Foaming Characteristics of Lubricating Oils" is commonly used for evaluating the foaming characteristics of lubricating oils. However, the ASTM test method does not always reproduce the same foaming characteristics of ATF in an actual automatic transmission. A new laboratory test method of foaming characteristics of lubricants has been developed to simulate the foaming characteristics of ATF in the automatic transmission, and it has been named "The Circulation Type Foaming Test Method." This test method has a high correlation with the foaming characteristics of ATF in the automatic transmission and sufficient repeatability as a test method. Furthermore, a small quantity of sample, short testing time and automated control are key characteristics. In this paper, the development procedure of this test method and each factor relating to the foaming characteristics is reported, such as sample volume, nozzle diameter and height, and impingement time.