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The development of new transmission designs continues to affect the vehicle market. Continuously variable transmissions (CVTs) remain one of the more recent designs that impact the vehicle market. A desire for high belt-pulley capacity has driven studies concentrating on metal-on-metal (M/M) friction as a function of the CVT fluid. This paper describes the statistical techniques used to optimize the fluid friction as a function of additive components in a bench-scale, three-element test rig.

High lubricant temperatures generated during the break-in of new differential assemblies has been of concern among original equipment manufacturers (OEM's). Many tests have been devised to measure the effects of speed, load and lubricant on the temperature generated in the axle. The major problem confronting the use of these tests has been a lack of repeatability and/or reproducibility. Recently, a European OEM axle lubricant break-in test procedure using a European sedan test vehicle has demonstrated highly repeatable and reproducible results. Test work had been limited to the European sedan. The applicability of the European OEM test procedure to a larger domestic U.S. vehicle was questioned. This paper discusses the applicability of the European test to a domestic sedan. Additionally, two other axle break-in test procedures were conducted using the same domestic sedan test vehicle. Three sulfur-phosphorus multi-purpose gear lubricants were evaluated.

Wet clutch friction devices are the primary means by which torque is transmitted through many of today's modern vehicle drivelines. These devices are used in automatic transmissions, torque vectoring devices, active on-demand vehicle stability systems and torque biasing differentials. As discussed in a previous SAE paper ( 2006-01-3271 - Next Generation Torque Control Fluid Technology, Part II: Split-Mu Screen Test Development) a testing tool was developed to correlate to full-vehicle split-mu testing for limited slip differential applications using a low speed SAE #2 friction test rig. The SAE #2 Split-Mu Simulation is a full clutch pack component level friction test. The purpose of this test is to allow optimization of the friction material-lubricant hardware system in order to deliver consistent friction performance over the life of the vehicle.

The popularity of SUVs and light trucks in North America, combined with the return to rear-wheel-drive cars globally, is significantly increasing the installation of torque control devices that improve vehicle stability and drivability. As with other driveline hardware, it is important to optimize the friction material-lubricant-hardware system to ensure that a torque control device provides consistent performance over the life of the vehicle. While there are many publications on friction tests relevant to automatic transmission fluids, the literature relating to torque control testing is not as well developed. In this paper, we will describe a split-mu vehicle test and the development of a split-mu screening test. The screening test uses the SAE#2 friction test rig and shows how results from this test align with those from actual vehicle testing.

Over several years, a fuel economy test measurement technique has been developed to highlight the magnitude of benefits expected in real world applications of different heavy-duty vehicle (HDV) engine oils in an operating vehicle. This method provides discriminatory results using an alternative to the widely used gravimetric fuel measurement methodology of Brake Specific Fuel Consumption (BSFC), in order to measure gains of <2% in a more repeatable manner. For the results to prove meaningful to the wider commercial audience, such as vehicle operators, original equipment manufacturers and oil providers, the systemic test vehicle operating conditions need to closely represent on-road conditions experienced on a daily basis by long haul, heavy duty diesel vehicles. This paper describes the parameters, necessary measures and methodologies required to record real world data and create representative proving ground test cycles.

Deposit formation within turbocharger compressor housings can lead to compressor efficiency degradation. This loss of turbo efficiency may degrade fuel economy and increase CO2 and NOx emissions. To understand the role that engine oil composition and formulation play in deposit formation, five different lubricants were run in a fired engine test while monitoring turbocharger compressor efficiency over time. Base stock group, additive package, and viscosity modifier treat rate were varied in the lubricants tested. After each test was completed the turbocharger compressor cover and back plate deposits were characterized. A laboratory oil mist coking rig has also been constructed, which generated deposits having the same characteristics as those from the engine tests. By analyzing results from both lab and engine tests, correlations between deposit characteristics and their effect on compressor efficiency were observed.

The constant velocity joint (CVJ) has seen increased usage driven by the growth of front wheel drive vehicles over the last 30 years. The CVJ provides a smooth, dynamic connection between the output of the axle or gearbox and the driving wheels of the vehicle. The seemingly simple device, however, requires specially designed greases to maximize protection of the internal components from distress and provide optimum performance and service life. One measure of potential distress in the CVJ can be related to temperature rise which is a reflection of the friction and wear properties of the grease employed. A test rig was designed and a method created to evaluate the temperature response of different greases used in a CVJ. The test rig was designed to allow a wide range of speeds, torques and shaft angles to be used. The rig uses a unique temperature pickup system to allow for dynamic measurement of the grease temperature in the boot.