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How to Select & Calculate Thrust Ball Bearings

Ball bearings are chosen as an important component in automobiles and other complex mechanical or electrical machines. The selection criteria ranges from power, to weight, heat and endurance. Engineers attempt to maximize their criteria for the machine they are building. Thrust capacity is one such important criteria and can be calculated using a basic formula. It is most associated with the length of usable life of the bearing.

Instructions

- 1
  Select a bearing to maximize your criteria. For thrust ball bearings, you generally seek to maximize for usable life.
- 2
  Find the variables that are needed to pursue the calculation. Most important, refer to the manufacturer of the ball bearings to find the dynamic rating and the design load of the material. The dynamic rating is a weight found on a chart from the manufacturer based on how the pressure is asserted to the axis. The design load is the amount of weight on the axis for the machine you are building.
- 3
  Enter each variable into the formula as follows:
  
  Life in hours = 10^6 * (dynamic rating/design load)^3
- 4
  Assume that the dynamic rating is 4,000 pounds and the load is 1,600 pounds. Insert the variables into the formula to find the useful life in hours.
  
  Life in hours = 10^6 * (4,000/ 1,600)^3 = 15,625,000 hours
- 5
  Compare the result of your calculation with other ball bearings and choose the maximum for your use in your machine.

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