Head Shaft (Typical) The diagram below illustrates typical equipment locations for head shafts in NRG rectangular clarification equipment. For more detailed information please refer to the arrangement drawings and product information sheets.   NUMBER DESCRIPTION STANDARD CONSTRUCTION OPTIONAL CONSTRUCTION 8A Wall Bearings Cast Iron w/Babbit Lining UHMW lined 8B Set Collars Cast Iron, Split UHMW or Nylon-6 8C 720 Sprockets Split UHMW or Nylon-6 UHMW Segmental Rim 8D H78 UHMW Segmental Rim Nylon-6 or UHMW 8E Shafting C1018 or C1045 Steel 304 or 316 s.s. * Keyways Refer to Standard Keyway Chart