* H SOCIETY OF AUTOMOTIVE ENGINEERS, INC. Two Pennsylvania Plaza, New York, N. Y. 10001 Type C-2 - A New Fluid for Heavy Duty Powershift Transmissions R. H. Schaefer R. L. Black Allison Division of General Motors SOCIETY OF AUTOMOTIVE ENGINEERS National Farm, Construction and Industrial Machinery Meeting Milwaukee, Wis. September 8-11,1969 690588 Downloaded from SAE International by University of British Columbia, Tuesday, September 25, 2018690588 Type C-2 - A New Fluid for Heavy Duty Powershift Transmissions R. H. Schaefer R. L. Black Allison Division of General Motors The mid 1940's marked the introduction of heavy duty Powershift transmissions to the earthmoving and construction industries. These transmissions were lubricated with en­ gine oils initially. The need for improved transmission fluids became apparent as early field experience revealed several serious fluid related problems, the most serious of which was sludging and varnishing. During this same time period the automo­ tive industry w a s also experiencing similar problems with the use of engine oils in passen­ ger car automatic transmissions. As a result, in 1949, General Motors was the first to ini­ tiate a qualification program for a specially formulated lubricant known as Type A. The heavy duty transmission manufac­ turers were also busy during this period de­ veloping another class of transmission fluids. The usage of special heavy duty trans­ mission fluids has proven their value over earlier use of engine oils in powershift trans­ missions. But due to continued demands by the earthmoving and construction industries for improved transmission performance and durability, the need for a significant increase in the quality of those transmission fluids be­ came apparent. Thus, a specification for a These fluids were to be different from the auto­ motive automatic transmission fluid since they were to be used in transmissions where gears and bearings are subject to very high loads over extended periods of time. As a result considerable emphasis was placed on the lu­ brication properties of the fluid. In many in­ stances these fluids are also to be used in final drives or even the vehicle's high pressure hy­ draulic system thus re-emphasizing the need for good lubricity. The heavy duty transmission fluids that were developed and are now commercially available (Table 1) have many similarities, yet individually t h e r e remain some distinct differences. These differences can be attri­ buted to the nature of the design of each trans­ mission and the importance each manufacturer places in the various functional requirements for his desired transmission fluid. new fluid, Type C-2, was developed. This paper discusses the new fluid speci­ fication in terms of its requirements, the pro­ cedures setup whereby the various companies of the oil industry may qualify their fluids, and the continuing program to evaluate the perfor­ mance of approved Type C-2 fluids. ABSTRACT Downloaded from SAE International by University of British Columbia, Tuesday, September 25, 20182 TABLE 1 - COMMERCIAL HEAVY DUTY TRANSMISSION FLUIDS Specification Originator Fluid International Harvester Hy-Tran John Deere JD-303 Caterpillar Series 3 Allison Division of GM Type C TRANSMISSION FLUID REQUIREMENTS A Powershift transmission fluid is re­ quired to function simultaneously as a: • Lubricant • Pressure medium for controls • Power transfer medium within a torque converter • Coolant Lubricant In the achieving of greater transmission durability, the lubrication of gears, bearings, thrust washers, etc. becomes more and more important. A good transmission lubricant must have film strength and extreme pressure (EP) properties compatible to the transmis­ sion design. Pressure Medium Powershift transmissions generally rely on hydraulic pressure as the means of apply­ ing clutches within the transmission. Low pressure pum