The dimensional tolerance and geometric deviation of fully loaded cylindrical roller bearings shall meet the tolerance grade P0 of gb/t307.1-94 (iso492- 1994), and the normal original radial clearance Co, or the bearings with C2 to C4 original radial clearance can be required. However, when ordering, the corresponding suffix should be added after the bearing code. C3 group clearance is generally selected for rubber and plastic screw extruder.