Force and Loading Analysis Four Point Contact Ball Bearings

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Four point contact ball bearings are capable of resisting radial, thrust, and moment loads, it is ordinarily subjected to a combination of two or more of these loads wherever it is applied. If used exclusively, instead of two angular contact or two radial contact bearings, it will usually have all three types of loading applied. If used in conjunction with a radial contact ball bearing, only thrust and radial loads are encountered. In either case, the effect of combined loads is best determined by a free-body analysis similar to that used for the angular contact bearings. Before proceeding with the analysis, a tentative bearing selection may be made by use of the following general formula for equivalent radial load: F

Where:

P_r = Equivalent radial load
F_r = Radial load
F_t = Thrust load
M - Moment load
PD = Bearing pitch diameter (inches)
= Bearing contact angle (30 for standard bearing)

When moment load is present, the known values, M, F_r, F_t, and (can be replaced within the formula to calculate a relationship between P_r and PD.  Once a tentative bearing requirement has been determined, the free-body analysis can be made as follows.