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Driveline Bearings Cut Friction by 30 Percent
Energy-efficient bearings are designed for cars, trucks and mobile equipment
Charles J. Murray -- Design News, September 28, 2009
SKF Group has rolled out a line of energy-efficient bearings for driveline applications that could cut friction by up to 30 percent and carbon dioxide emissions by up to 13 gm per mile.
The new bearings offer reduced friction on an application-by-application basis for cars, trucks, agricultural equipment, construction machinery and even wind turbines.
"The real target is to minimize the friction by applying lower loads to the rolling elements," says Thomas Wolf, senior engineer for powertrain and steering at SKF's Automotive Div. in Germany. "Whether it's a car or a piece of construction equipment or a truck, the idea is always to reduce the friction."
SKF accomplishes that by applying its Vehicle Environmental Performance Simulator (VEP) software program to individual design applications. The simulator uses a variety of inputs, including engine torque, engine speed, vehicle mass, air drag and rolling resistance of tires to help determine the loads on the bearings. By knowing the loads, the resulting stresses, stiffness matrix and the desired bearing life, the program can optimize the internal geometry of the bearing, including the number and diameter of rolling elements, as well as the contact angle.
SKF's portfolio of low-friction bearings includes tapered roller bearings, angular contact ball bearings for drivelines, double-row ball bearings for pinion units and hybrid pinion units with double-row bearings with balls and tapered rollers.
By doing the VEP analysis on its portfolio of bearings, SKF claims it can reduce friction by as much as 30 percent. Wolf says the bearings are designed for use in virtually any type of mobile application.
"Even wind turbines can use the energy-efficient tapered roller bearings," he says. "But drivelines are still the application that is most promising for energy reduction."
