Wet start clutches put new, more severe, requirements on the lubricants used in these transmissions. The fluids must provide the correct friction versus velocity characteristics to prevent clutch shudder and maintain those characteristics for long periods of time to allow extended drain intervals for the fluids. While many methods exist for characterizing the frictional behaviour of clutch materials and fluids under conditions of high energy engagements, no standard test exists for measuring the friction durability of transmission fluids in a mixed operational mode of high energy engagements and sliding for long periods of time at low speeds. In response to the need for a test to assess friction durability requirements of torque converters with regulated clutches (GWK) the authors have developed a test method using a modified SAE2 machine. A test cycle was developed in which the clutch is slipped under steady state conditions for 50 minutes. A program was begun to develop a new friction system that would allow for significantly longer friction control than the conventional friction systems used in ATF-1 and ATF-2. This program yielded a family of friction modifying chemicals that can be treated at concentrations over ten times that of conventional friction modifiers.
Formulating fluids with improved friction durability for wet start clutches
Schmierstoffe mit erhöhter Reibungsfestigkeit für Anfahr-Nasskupplungen
2004
12 Seiten, 10 Bilder, 3 Tabellen, 3 Quellen
Conference paper
English
Formulating Fluids with Improved Friction Durability for Wet Start Clutches
British Library Conference Proceedings | 2004
|Friction clutches on automobiles
Engineering Index Backfile | 1904
Systematic development of friction clutches
TIBKAT | 2015
|The effect of separator flatness on the performance and durability of wet friction clutches
Automotive engineering | 1993
|Formulating Automatic Transmission Fluids with Improved Low Temperature Fluidity
SAE Technical Papers | 1990
|