Takayama, Y., "Wheel Bearing Lubrication Development for Low Friction and Water Resistance," SAE Technical Paper 2016-01-1960, 2016, doi:10.4271/2016-01-1960.
Recently, vehicle production volumes have been increasing, particularly in newly developing countries that often lack adequate infrastructure. These regions utilize many unimproved roads and frequently experience heavy rainfall, requiring robust product features. In contrast, developed countries, with well-maintained infrastructure, have emphasized protection of the environment, requiring automobile manufacturers to target reductions in carbon dioxide emissions. Hub unit bearings, which enable smooth wheel rotation, are mounted at the wheel center. The hub bearing is a critical part which supports the automotive body and requires high reliability. To make environmental progress, hub unit bearings have increasing requirements for low friction.NSK has developed effective grease technologies to meet the diverse requirements of hub unit bearings, such as high reliability and low friction under severe environmental conditions. Under wet operating conditions, the developed grease extended bearing life by using a unique composition of synthetic base oil with additives for water resistance which can separate water drops and form a thicker oxide film on the bearing raceways. At low speeds and heavy load conditions, the developed grease decreased friction torque via the base oil’s low viscosity-pressure coefficient. This paper reports the results of testing and observations completed for the developed grease.