China 
Africa 
Explore chapters and articles related to this topic
Grease Lubrication
Published in W. S. Robertson, Lubrication in Practice, 2019
Lithium soap greases have the advantage of being water-resistant and also of having fairly high melting points, typically about 180 °C. These greases therefore are often used as multi-purpose greases as they enable several other greases to be replaced by a single soap type[3,4].
Automotive Chassis Components
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
Several grease formulations are used and provide acceptable performance in these applications. Most of these formulations are similar to NLGI (National Lubricating Grease Institute) No. 2 in consistency and are made with an oil component approximating ISO (International Standardization Organization) viscosity grade 150 or 220. They are intended for multipurpose use. In addition, special applications, such as wheel bearings on disc brakes, require greases that are resistant to high temperatures. Lithium soap base greases, which are used to a considerable extent, are modified by the addition of extreme pressure and antiwear additives to provide better load-carrying capabilities and lower wear rates. Colloidal or fine particle size solid lubricant materials such as molybdenum disulfide are often added, particularly when the grease is intended for use in passenger car suspensions and off-highway equipment pivot and hinge pins. These materials generally reduce both friction and wear.
Additives for Grease Applications
Published in Leslie R. Rudnick, Lubricant Additives, 2017
Robert Silverstein, Leslie R. Rudnick
The general performance and properties of grease as a function of thickener are as follows:An aluminum soap–thickened grease generally exhibits excellent water resistance, poor mechanical stability, excellent oxidative stability, good oil separation, and poor pumpability and, in general, can be used to a maximum application temperature of 175°F (79.5°C).A calcium soap–thickened grease generally exhibits excellent water resistance, fair mechanical stability, poor oxidative stability, excellent antirust performance, and fair pumpability and, in general, can be used to a maximum application temperature of 250°F (121°C).A lithium soap–thickened grease generally exhibits good water resistance, excellent mechanical stability, good-to-excellent oxidative stability, poor-to-excellent antirust performance depending on the formulation, and fair-to-excellent pumpability and, in general, can be used to a maximum application temperature of 275°F (135°C).An aluminum complex soap–thickened grease generally exhibits excellent water resistance, good-to-excellent mechanical stability, and good pumpability and, in general, can be used to a maximum application temperature of 350°F (177°C).A calcium complex soap–thickened grease generally exhibits excellent oil separation and good mechanical stability, the thickener in this case provides a degree of AW and EP protection, and in general, it can be used to a maximum application temperature of 350°F (177°C).A lithium complex soap–thickened grease generally exhibits excellent oil separation and moderate water resistance and, in general, can be used to a maximum application temperature of 350°F (177°C).Clay-thickened grease has good-to-excellent water resistance, good pumpability, and excellent oil separation and, in general, can be used at maximum application temperatures greater than 350°F (177°C).Polyurea-thickened grease has excellent oxidative stability, excellent pumpability, and excellent oil separation but has poor worked stability and fair-to-modest antirust performance. These greases can be used at a maximum application temperature of 350°F (177°C). Polyurea greases soften easily but are reversible.
Rail Grease Formulation Effect on Its Tribological Performance Under Pure Sliding Conditions
Published in Tribology Transactions, 2023
B.P. Ferrer, L. Biazon, A. Zuin, P. Tayer, A. Toro, T. Cousseau
Six lubricating greases were formulated to evaluate the effect of thickener type and base oil viscosity on friction and wear of the metallic pairs, as well as on the ejection speed of the grease. All formulations used mineral base oil and a state-of-the-art additive package for extreme pressure applications, currently used in several railways in Brazil. The additive package contains usual antioxidants, dispersants, detergent, EP, AW, and FM compounds, plus 5% of MoS2 solid additives with average 5 µm size. Two thickener types, namely, lithium soap and calcium soap, and three base oil viscosities, 50 mm2/s, 200 mm2/s, and 500 mm2/s, were used in the formulation. Three commercial greases, with one of them being biodegradable, were also evaluated for comparison purposes. Therefore, it is also possible to evaluate the effect of additive package, oil, and other thickener types, although not in a systematic way. Table 2 presents the main properties and designations of the greases. All lubricating greases present grade NLGI 2, which corresponds to the consistency of the commercial lubricating greases for curve rail lubrication used in countries with a tropical climate, like Brazil.
Microstructure Characterization of Degraded Grease in Axle Roller Bearings
Published in Tribology Transactions, 2019
AFM topography and its matched spots phase-contrast images of fresh and aged grease samples are shown in Figs. 4–8. Both topographical (Figs. 4a and 4c) and phase-contrast (Figs. 4b and 4d) images reveal that the lithium thickener of fresh grease formed a disordered three-dimensional network structure. Occasionally, solid particles were seen in between the fiber network (Fig. 4a). Compared to the surface topography (Fig. 4c), the phase-contrast AFM image (Fig. 4d) evidently shows that the lithium thickener consists of self-twisted and/or entangled nanofibers. The variation of microstructure of early life grease is given by Fig. 5 and Fig. 6. An example of AFM image artifacts from the unwashed aged grease sample is shown in Fig. 5. More detailed images can be found in Fig. A1–A3 in Appendix A. Fresh-look grease samples, especially those from the inner surface of the outer race and between rollers (see Fig, 1a), had a less twisted morphology (Fig. 5) in comparison to those seen in Fig. 4. For the majority of early life grease, the long and continuous lithium fibers were absent and either shorter fibers or irregularly shaped clusters were present, illustrated in Fig. 6. The microstructure of the medium (Fig. 7) and heavily (Fig. 8) used grease show the fibrous structure of thickener had vanished. The former lithium soap fibers now consist of irregular-shape and/or granule-like nanosize particles. AFM images of medium and heavily used aged grease also reveal that degraded thickener had agglomerated, leading to a denser microstructure compared to that seen in the fresh grease.
Tribological Properties of Rock Bit Journal Bearings for Journal with Nanosecond Laser Surface Texture
Published in Tribology Transactions, 2020
Lin Zhong, Gang Wei, Guorong Wang, Xia He, Guihong Feng, Zongzheng Dong
The high-speed roller bit bearing is lubricated by compound lithium-based grease (RB grease). Figure 2 shows the curve of the change in shear stress and viscosity of RB grease with shear rate at 100 °C. The kinematic viscosity of the base oil of this grease is 49–160 mm2/s at 50 °C and 9–21 mm2/s at 100 °C. Thehickener is a compound lithium soap mixed with a certain proportion of acetic acid, caprylic acid, and stearic acid and then mixed with structural improvement agents lead acetate and antioxidant phenyl alpha naphthylamine. The base grease prepared from the above raw materials plus a certain proportion of MoS2 and Sb2O3 is rolled to make the cone bit grease.