FourPoint bearings Do Triple Duty While Saving （FourPoint轴承做三重责任而储蓄）.pdfVIP

TECHNICAL Four-Point Bearings Do Triple Duty While Saving Space Rick Burgess and Dave Van Langevelde A four-point contact ball bearing makes it easy to simplify machine designs that combine radial, thrust and moment loads, because it can handle all three simultaneously. They are primarily used for slow-to-moderate-speed applications, or where oscillatory movement is predominant. A single, four-point contact bearing usually makes a sec- ond bearing unnecessary, which provides some very impor- tant benefits, including: • Space savings • Weight savings • Cost savings • Rigidity and accuracy • Faster installation • Less maintenance • Integral mounting holes, gears, etc. Thanks to a unique ball path geometry that produces twice as many contact points, a four-point contact bearing can re- sist radial, thrust and moment loads individually, or in any combination. It has one row of balls with an inner race and an Figure 1 A four-point contact bearing can resist radial, thrust and moment loads individually — or in any combination. outer race. The ball grooves are generated from two centers, with each radius slightly larger than the ball radius. Contact angles are typically 35° off the radial centerline, but can be varied to suit the application. Important Advantages Four-point contact bearings are especially effective in ap- plications in which the rotating element has a high ratio of diameter to axial length. Most have a large ratio of bore-to- section size: the larger this ratio, the thinner and more flex- ible are the individual races. Thin section bearing sizes range from 1– 40and slewing ring bearings range from 4 – 178 O.D. Figures 1 and 2 show how much space can be saved by