Bearing Load: Standard 1.9" (50mm) diameter conveyor rollers are normally rated at 250 lbs (110 kg) maximum load. The plastic fixture that holds the bearing is the limiting factor. For idler pulleys the maximum load is determined by the bearing itself. Our idler pulleys use the 6203 bearing, rated at 600 lbs (270 kg) at typical conveyor speeds. Make sure that your belt tension does not exceed the rating of your application.
*Tension vs. Time: Urethane belt tension declines dramatically after installation. In the first 5 minutes it typically declines by 30%. After about a week of run-in the tension plateaus and remains relatively constant thereafter, declining very slowly at a diminishing rate over time. The chart below shows an example of this. Incidentally, dynamic tension always measures below static tension, so if this test were done without rotating the rollers, the plateaued tension would be about two pounds higher.