Type II OGL Development

Next in our OGL study, the effects of base oils in higher kinematic viscosity fluid type OGL were tested. We started with grease types and now wanted to validate that we saw similar effects in fluid types and determine if the thickener system contributed anything significant to the performance advantage presented in the UPP sample or the performance benefits were primarily attributed to the UPP. The Type II OGL fluids that were developed were blends of oils and kinematic viscosity modifiers that were then treated with the same. The formulations for these OGLs can be seen in Table 9. Components Mineral OGL, % weight PAO OGL, % weight UPP OGL, % weight Polyisobutylene (Mn2000) 68 65   Brightstock (BS150) 24     PAO-100   27   UPP 2000     78 Group II 600 N     14 Additive package 8 8 8 Table 9—Type II fluid OGL formulations. It is important to note that the PAO OGL required a heavy amount of PIB to meet the required viscosity requirements. Although PAOs have been shown to provide thermal stability, they do not offer high viscosity options like the UPPs. Since there are a wide range of UPP viscosity options, there is much more flexibility to formulations. The individual requirements for this study are captured in Table 10 and are like the grease type requirements presented in the previous section Table 2. Load carrying was one stage lower. Based on the nature of these materials being fluid type, the additive pack is similar to additive package used in the grease study but not identical. Each of the Type II OGL fluids were evaluated for the properties seen in Table 10.

Property Test method Target Mineral OGL PAO OGL UPP OGL Kinematic viscosity at 40°C ASTM D445 Report 30,400 20,000 16,500 Kinematic viscosity at 100°C ASTM D445 850-950 877 861 926 Viscosity index ASTM D2270 Report 195 228 258 Pour point, °C ASTM D5950 Report 3 6 -9 Rust protection ASTM D1743 Pass Pass Pass Pass Copper strip corrosion ASTM D130, 100°C, 3 h 1B 1B 1B 1B 4-ball weld point, kgf ASTM D2596 800 620 800 800 LWI, kgf Report 128.8 144.4 145.2 4-ball wear scar diameter, mm ASTM D2266 0.6 0.73 0.50 0.46 Table 10—Type II fluid OGL formulations. Like the Type I OGLs, UPP again seems to have played a role in the reduction of the wear scar compared to the mineral oil OGL. It was also observed that the Mineral OGL does not perform as well as the PAO and UPP OGL in the load carry. These results suggest that base oil modifications and identity to a fluid type OGL may influence overall performance. An additional observation that was made was the decrease in pour point of the UPP OGL compared to the other two fluids, which suggests that the UPP OGL may be easier to handle. In similar fashion to the Type I OGL studies, FZG testing was also conducted on the Type II fluid OGLs on the same test stand. The test conditions used were specifically for a fluid type—A/8.3/90. All fluids completed 12 load stages without scuffing. The end of test operational temperatures were compared, using the Mineral OGL as the baseline. The results can be seen in Figure 9.

The UPP OGL completed load stage 12 at a temperature 15°C cooler compared to the Mineral and the PAO OGLs. The PAO and Mineral OGL seemed to perform identically which is likely due to the similar amounts of PIB needed to achieve their desired viscosities. While this test was being conducted, thermal images were again taken so that the temperature differences could be visualized in Figure 10.

The color profile of these thermal images is different than the images of the Type I grease OGLs in Figure 5 because a different imaging software was employed. The images show that both the Mineral OGL and PAO OGL run at an elevated temperature in comparison to the gear box running in the UPP fluid OGL. The energy consumption data collected from this testing correlated to the thermal data as well. Energy consumption data calculation was executed as indicated in the previous section. The results from the FZG testing found that the UPP OGL consumed 13 percent less energy compared to the Mineral OGL and 11 percent less energy compared to the PAO .

Similar to the Type I OGL development, we wanted to translate the Type II development in the field applications. The first trial occurred at a sugar mill in North America where the OGL was designed for the open gear as well as journal bearings. The fluid OGL was applied to journal bearings (decided by the refinery) for the duration of one season of sugar cane refining. The conditions an OGL faces in sugar mill are extremely harsh and include: high temperature, high humidity, juice and water contamination, high presence of dry and wet bagasse as well as constant power washing.