Page 7 of Fiberglide by RBC Bearings

Ž bearings coefficient of friction coefficient of friction coefficient of friction depends upon type of movement finish of mating surface ambient temperature bearing pressure velocity and other variables figs 1 2 and 3 were obtained from flat specimens and may be used as a guide note in fig 1 that the coefficient drops off as bearing load increases this offers the advantage of using the smallest bearing sizes to obtain the least amount of friction fig 3 shows the coefficient of friction increasing as surface velocity increases from 2-20 fpm this feature is particularly valuable for vehicle steering systems .10 .08 .06 .04 .02 0 2,000 4,000 5,000 8,000 10,000 70°f 150°f 300°f contamination fiberglideŽ can tolerate small amounts of dirt but reduced bearing life will result optimum life is achieved if dirt or abrasive particles are excluded if a dirty environment is likely we recommend installation of a simple seal sliding speed 0.5 fpm load psi fig 1 effect of load and temperature on fiberglideŽ bearing running clearance as a general rule close running fits and often slight interference fits 0005 in are selected for oscillating motion when minimum starting torque is less important than the elimination of free play for constant rotation a free-running fit is normally recommended the exact amount depending on bearing bore size a rule of thumb would be 0.0015 inches per inch of bore bearing installed coefficient of friction .18 .15 .12 .09 .06 .03 0 -400 -200 0 200 400 bearing housing shaft sizing standard fiberglideŽ journal bearings cjs/cjt cjm/cjh/sjr type are installed into the housing bore using a press fit recommended housing bores should be held to the tolerance shown to insure the proper fit and size the ljs type bearing is hand slip fit into its recommended housing bore to provide optimum fit-up cjs/cjt/cjm/cjh types can also be provided for slip fits on special order transport dynamics offers a special service to properly size housing and shaft for each new application contact transport dynamics engineering department for details temperature °f fig 2 effect of temperature on coefficient of friction fluid compatibility fiberglideŽ can tolerate most fluids or contaminants found in bearing applications although some reduction of dry bearing life will result fluids tend to flush ptfe solid particle lubricants out of the bearing grease tends to act as a magnet to attract and retain dirt following are some of the environments in which these bearings have operated successfully hydraulic oils mild acids greases gasoline lubricating oils detergent solutions ammonium hydroxide liquid nitrogen seawater toluene kerosene coefficient of friction .06 .04 .02 0 10 20 30 40 50 surface speed fpm fig 3 coefficient of friction at 10,000 psi normal unit load and 70°f vs surface speed 5

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