So you though this was a simple component did you?
The photograph shows each element in its relative position.
The fan blade is a steel frame to which the aluminium blades are riveted. The blades are embossed where they meet the centre piece to reduce the risk of stress fracture. Not shown in this picture are the matching steel triangles which sandwich the blades where the rivets are inserted.
The front cap has a circular flange underneath which acts to centralise the fan and also as a grease seal for the front bearing.
The bearing spacer tube has an inner radial flange at its forward end to match the taper on the fan axle.
The smaller of the two nuts (bottom right) locks up against the shoulder on the rear of the axle and holds the rear washer loosely in place. The larger nut is hollow, winds up to cover the small lock nut, and its flange clamps the rear washer to the fan mounting on the timing cover after the fan belt has been tensioned.
When re-assembled, a small amount of grease should be packed in the blade support tube to ensure that the bearings do not run dry.