Detail: SBF-supporting rolling wheel has the characteristic of thick outer circle. Rolling wheels can roll on it. Great workload can be born. The shape of rolling whels is cylinder or arc. Arc can avoid rim stress. Main structure forms: STO rolling wheel needle bearing without blocking rim RNA22-2RS rolling needle bearing without internal circle. Outer circle has two blocking rims. Both sides have sealing circles. NA22-2RS both sides have sealing circles. It is rolling wheel needle bearing without internal circle hose outer circle has blocking rim NATR level blocking circle rolling needle bearing NATV level rolling full needle bearing NUTR level rolling full cylinder bearing