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Hydraulic fluid (HF) specifications for mobile construction equipment called JCMAS HK and HKB have been established by the Fuels and Lubricants Committee of Japan Construction Mechanization Association (JCMA). The specifications are designated by two viscosity categories of single grade and multigrade. Each category has ISO viscosity grade (VG) 32 and 46. The JCMAS HK oils are recommended for use in hydraulic systems designed at pressure up to 34.3MPa(5000psi) and to heat hydraulic fluid up to 100 °C. These oils also provide wear control, friction performance, oxidation and rust protection, seal swell control and filterability performance. Two piston pump test procedures were developed to evaluate lubricating performance of these oils under high pressure conditions. The JACMAS HKB oils are classified as environmentally friendly oils due to the additional requirement for biodegradability.

This paper reviews the development of a new standard for four-stroke diesel engine oils, JASO DH-1 (JASO M355: 2000). This standard was introduced to the market on April 1, 2001. It prescribes the minimum performance for engine oils conforming to four-stroke diesel engines manufactured by Japanese OEMs. This standard is composed of four engine tests and seven bench tests. The engine tests include a piston detergency test (JASO M336: 1998), valve train wear test (JASO M354: 1999), soot dispersancy test (ASTM D 5967-99) and high temperature antioxidation test (ASTM D 5533-97a). The piston detergency test and the valve train wear test were developed in Japan. The bench tests measure hot surface deposits, anti-forming, volatility, anti-corrosion, shear-stability, total base number, and seal compatibility.

We have found that most commercially available biodegradable hydraulic oils show low static friction coefficients not depending on the kinds of wet friction materials. Since hydraulic motors of a hydraulic excavator contain wet parking brakes, the most commercially available biodegradable hydraulic oils can not provide enough brake torque capacity to park safely. Furthermore, all kinds of commercially available biodegradable hydraulic oils do not have adequate oil performance for a hydraulic system of construction eq ipment. Thus we have developed a n high performance biodegradable hydraulic oil. To obtain a high static friction coefficient and compatibility with elastomers, a new synthetic ester base fluid has been developed. To improve oxidation stability and to attain compatibility with mineral oil based hydraulic oils,. an additive formulation has also been developed.

Recently high copper concentration of used oils has been frequently detected in our oil analysis system, although any excessive wear of the copper parts in the engines and the power-train was not detected. We have found the copper comes from copper solder in the oil cooler. Thus we have investigated the copper corrosion characteristics of commercially available engine oils and power-train oils in a laboratory test. Most power-train oils did not show copper corrosion, however some engine oils showed large weight loss of a copper test piece. In a field test of off-road dump trucks, we have found that the copper, dissolved in the oil, caused glazing and friction reduction problem of the wet brake paper disk. To clarify the glazing mechanism of the disk, simulated bench tests and used oil analysis have been conducted.

A new non-black (colorless) heavy load grease, having superior anti-seizure property and multi-purpose performance for construction machines, has been developed. The main components of the non-black heavy load grease are apertinent viscosity base oil, lithium complex soap and a unique non-black solid lubricant (phosphate glass). The weld load of the new non-black heavy load grease is 4900 N by the four ball EP tester. This value is almost the same as that of 60% molybdenum disulfide paste. The several type grease samples, mixed with 1 % clay dust, were evaluated by the four ball EP tester. The multi-purpose EP lithium grease lost the antiwear property and the MoS2 grease maintained antiwear property. The new non-black heavy load grease shows the best antiwear property against the clay dust. Furthermore, a number of laboratory tests have been conducted to prove the multi-purpose performance for construction machines.

To adapt biodegradable hydraulic oils to heavy-duty construction machines, we have investigated eight commercially available vegetable-based biodegradable hydraulic oils for an oxidation stability and corrosion characteristics by laboratory tests and an axial piston pump rig test. From the laboratory tests, it became clear that all vegetable hydraulic oils show poor oxidation stability and two vegetable hydraulic oils show strong corrosion to bronze materials. Three vegetable hydraulic oils, which contain 0.7 %, 0.25 % and 0% sulfur, have been tested by a high pressure axial piston pump. The 0.7 %S vegetable hydraulic oil resulted in rapid viscosity increase and serious bronze corrosion in the 32 MPa x 95°C pump test. In the 32 MPa x 80°C pump test, the oxidation and corrosion of the 0.7 %S vegetable hydraulic oil were much lower. To compare the vegetable hydraulic oils, 42 MPa x 80°C pump tests were conducted.

In order to extend the oil drain interval and to prolong the engine service life, we have investigated the effects of engine load and wear on heavy-duty diesel engine oil deterioration and oil filter plugging. Furthermore, effects of oil quality on oil deterioration has also been studied. We have found in this study that the increase of blow-by gas flow due to excessive wear of engine components causes severe nitro-oxidation in heavy-duty diesel engines at a high engine load conditions similar to that observed in gasoline engines. The nitro-oxidation of engine oil also causes filter plugging. From the oils tested, the high ash oil showed better anti-nitro-oxidation performance than those with low ash.

From investigating the porosity and graphite effects on sintered bronze for wet clutch applications, it is clear that elasticity, as determined by the porosity and the graphite content, is important for both the friction coefficient and the power absorbing capacity. The apparent elastic modulus values, measured by a compression test of clutch disks, show a very good correlation with performances of various wet friction materials (sintered bronze, paper, graphitics and elastomerics) in both an inertia-brake type clutch testing machine and also on the full-size powershift transmission bench. The lower elastic modulus material has the higher friction coefficient and the better energy/power absorbing capacity. Effects of the material pores, the oil-groove patterns and also the material deterioration on friction performances and hot-spot size are discussed in conjunction with apparent elastic modulus.

A new antifreeze coolant has been developed for the heavy-duty diesel engine. This anti-freeze coolant has better anticorrosion performance than Supplemental Coolant Additives (SCAs) and has longer life than commercial permanent-type coolants. The new antifreeze coolant is composed of ethylene glycol and corrosion inhibitors. In glass ware tests, the new antifreeze coolant showed the best anticorrosion performance in cast iron, aluminum and other metals. The anticavitation pitting property and anti-oxidation property were also tested. In order to evaluate the new antifreeze coolant, a bench engine test procedure has been established. Since the new antifreeze coolant caused light cylinder liner pitting on bench test, antifoaminq property of the coolant was improved. The improved coolant showed excellent performance against cavitation-pitting and aluminum corrosion on engine bench and in the field.

To prevent engine scuffing in the field a new laboratory test called the Hot Tube Test has been established in order to evaluate the high temperature stability of diesel engine oils. In a strip mining application field test using 47 bulldozers powered by the same engine type, half of the engines suffered from piston scuffing failures when operated on a variety of commercially available API CD quality SAE 30 Grade engine oils. All the field test oils have been investigated using the Hot Tube Test, and an analysis of the results indicates that it would be possible to accurately predict scuffing failures by this test method. Furthermore, the reliability of this analysis has been verified by bench engine testing on reference oils. The reasons why the Hot Tube Test predicts the anti-scuffing performance of engine oils are discussed.