Preload and accuracy are separate selections. The catalog uses T0 for clearance, an unmarked standard setting and T1 for light preload where available. Select the grade against torque, stiffness, friction and the complete operating load case.
Normal, High and Precision grades describe component tolerances, not whole-machine positioning performance. Housing fit, shaft alignment, supports, thermal effects and the drive system still determine the installed result.
Interchangeable parts require the same precision grade and matching S1/S2 identification. Supplied non-interchangeable pairs must not be freely mixed. Confirm available suffixes and mating rules on the exact series drawing.