Search Results

Modern agriculture has evolved dramatically over the past half century. To be profitable, farms need to significantly increase their crop yields, and thus there are amplified demands on farming equipment. Equipment duty cycles have been raised in scope and duration, as the required output of the agricultural industry to sustain a growing population has stimulated the need for further advances in effective productivity gains on the farm. The mainstay mechanical assistant to the farmer, the tractor, has also evolved with the changes in modern agriculture to meet the requirements of these newer tasks. Larger, more capable vehicles have been introduced to help farmers efficiently meet these demands. At the same time, the current generation of tractor diesel engine lubricants has facilitated high levels of performance in the agricultural equipment market for many years. This is a testament to the role modern lubricants play in productivity in such a critical industry.

This paper is part one of a longer term comparison of viscosity modifier behavior in modern automotive gear oil (AGO) fluids and the impact of these properties on fluid efficiency and durability. This first installment will compare the rheological properties, including EHD film thickness and traction coefficients, of the fluids across broad operating temperature, shear and load regimes and correlate these findings with rig efficiency testing. The effects of traction, EHD film thickness and high shear rheology on operating temperature are well documented and it is of particular interest to determine the extent to which different viscosity modifiers can beneficially impact these properties compared to a Brightstock-based SAE 80W90 grade fluid. The efficiency improvements of a VM would be for naught if it were not sufficiently shear stable and so comparisons are made between shear stable VM technologies.

Driven by global demands for improved fuel economy and reduced emissions, significant improvements have been made to engine designs and control systems, vehicle aerodynamics, and fuel quality. Improvements, such as the continuously slipping torque converter, have also been made to automatic transmissions to increase vehicle efficiency. Recently, belt-continuously variable transmissions (b-CVTs) have been commercialized with the promise of significant fuel economy improvements over conventional automatic transmissions. Automotive traction drive transmissions may soon join belt-CVTs as alternative automatic transmission technology. Much of the information reported in technical and trade publications has been on the mechanics of these traction drive systems. As automotive traction drives move closer to commercial reality, more attention must be given to the performance requirements of the automotive traction fluid.

The International Lubricant Standardization and Approval Committee (ILSAC) GF-2 requirements for Passenger Car Motor Oils (PCMOs) will lower phosphorus limits from a maximum of 0.12% allowed by ILSAC GF-1 to a maximum of 0.10%. In effect, the ILSAC GF-2 phosphorus limit removes 17% of the most commonly used antiwear and antioxidant additive in current PCMOs, zinc dialkyldithiophosphate (ZDP). This paper outlines some work in ASTM Sequence V engine dynamometer tests to quantify the effect of reducing the ZDP on valve train wear and sludge formation. Engine data for the Sequence VE, the proposed Sequence VF, and the modified Sequence VE are presented. These three tests summarize the evolution of the Sequence V from the Sequence VE for GF-1 to the dual plug Sequence VE configuration for the GF-2 specification.

Recent commercial specification revisions for automatic transmission fluids (ATFs) have focused upon more stringent friction requirements. More stringent friction durability characteristics are assessed using the SAE No. 2 tester. The commercial specifications do not include provisions to evaluate low speed friction characteristics, which have been shown to relate to torque converter shudder. This paper focuses upon effective use of the Falex 6 Multispecimen Tester to evaluate friction durability and to evaluate low speed friction characteristics in conjunction with low speed friction apparatus (LVFA) testing. Falex 6 testing agreed with torque fade observed in SAE No. 2 tests. Low speed stick-slip durability characteristics were effectively differentiated for a number of field ATFs. Falex 6 testing coupled with LVFA testing was shown to correlate with field experience and other test methods related to torque converter shudder.

Multifunctional additives can compensate for lower quality diesel fuel. Performance and quality have been decreasing worldwide. This has resulted largely from increased use of heavier crude oils and more severe processing to achieve necessary fuel product mix. Fuel additives provide the refiner and marketer with an economic approach to restoring performance and quality. Additives can be formulated to solve many problems related to deposits and wear, which are major factors affecting engine power, economy, emissions and durability. They are of critical importance to the vehicle owner/ operator to maintain dependability and low operating cost. At the same time, the refiner benefits economically through the use of lower cost crudes, greater operational flexibility and ease of adjusting final fuel blends to meet specifications. Typical additive components include: detergent dispersants, inhibitors, stabilizers, cetane improvers, and flow improvers.

Emissions system durability may be influenced by many engine oil formulation variables. Previous studies have suggested that emissions system durability is optimized by high metal/phosphorus ratios. Reducing the level of phosphorus in the engine oils has also been suggested as a means of prolonging the efficiency of the catalytic converter. This paper explores engine oil formulation variables which may influence the efficiency of the emissions system. Phosphorus type and amount are examined as potential catalytic deactivators, as well as detergent metal interactions with the phosphorus. Dynamometer and over-the-road test data are presented which suggest that the volatility characteristics of the phosphorus component in the engine oil may influence the degree of catalyst contamination. To explore fully the many variables, however, will require an emissions performance test.

This paper provides an overview of gear lubrication related to automotive equipment. A brief background in various aspects of lubrication, including lubrication theory, lubricant evaluation, performance designations, and formulation technology, is presented. This information is designed to assist those involved in the selection of automotive gear lubricants.