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Bearings and Lubrication
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
Greases are liquid lubricants that have been thickened (by mixing with soaps) to provide properties not available in the liquid lubricant alone. Mineral oils are the most commonly used liquid for this purpose. Greases are often used where the lubricant is required to stay in position. Unlike oils, greases cannot circulate and thereby serve a cooling and cleaning function; however, they are expected to accomplish all functions of fluid lubricants. The many types of greases have properties suitable for a wide variety of operating conditions. Typical uses of greases include vehicle suspension and steering, for gears and bearings in lightly loaded and intermittent service, with infrequent lubrication by hand or grease gun.
Bearings and Lubrication
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, MECHANICAL DESIGN of Machine Components, 2018
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
Greases are liquid lubricants that have been thickened (by mixing with soaps) to provide properties not available in the liquid lubricant alone. Mineral oils are the most commonly used liquid for this purpose. Greases are often used where the lubricant is required to stay in position. Unlike oils, greases cannot circulate and thereby serve a cooling and cleaning function; however, they are expected to accomplish all functions of fluid lubricants. The many types of greases have properties suitable for a wide variety of operating conditions. Typical uses of greases include vehicle suspension and steering, for gears and bearings in lightly loaded and intermittent service, with infrequent lubrication by hand or grease gun.
Application of Lubricants
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
Greases are primarily used to lubricate rolling element bearings, flexible couplings, and thin film plain bearings and slides. Greases are also used in some open and enclosed gear applications. Because of the lower leakage tendencies of greases, periodic application with a hand- or air-powered grease gun does not have many of the disadvantages of hand oiling, but—as with any manual lubrication method—grease fittings can be overlooked and the cost of application is usually high. Therefore, central grease lubrication systems are being used more frequently, and a number of bearings are being “packed for life.”
On the Shear Stability of Dry and Water-Contaminated Calcium Sulfonate Complex Lubricating Greases
Published in Tribology Transactions, 2019
Yuxin Zhou, Rob Bosman, Piet M. Lugt
To study the grease shear stability, shear aging was performed using an in-house-made Couette aging machine. As shown in Fig. 3, fresh greases were inserted into the Couette aging head by using a grease gun. Then, the aging head was closed and the grease was sheared between the rotating bob, driven by a motor (connected to the bob by means of a magnetic coupling) and the stationary housing for different periods of time. During the aging tests, base oil evaporation, leakage, and oxidation did not occur due to the airtight environment created by the o-ring sealing and the closed aging head. Because this was a continuation of our previous aging work for lithium and polyurea greases (Zhou, et al. (17)), the same aging conditions were applied; that is, the motor was run at 50 rpm, creating a uniform shear field within the gap between the bob and housing (). To include thermal effects in the study, aging was carried out at different constant temperatures inside a thermal bath. The Couette aging conditions are shown in Table 2. For more details on the Couette aging machine, the reader is referred to Zhou, et al. (17).