3329Lubricated Bronze Bearing Plates and Bushings

3329.1SCOPE

Provide aluminum bronze bearing plates and manganese bronze bushings.

3329.2REQUIREMENTS

Provide aluminum bronze bearing plates meeting the requirements of ASTM B505, Standard Specification for Copper Alloy Continuous Castings, Alloy C95400 or Alloy C95500; ASTM B148, Standard Specification for Aluminum-Bronze Sand Castings, Alloy C95400 or Alloy C95500; or ASTM B169, Standard Specification for Aluminum Bronze Sheet, Strip, and Rolled Bar, Alloy C61400, Temper M20. Provide manganese bronze bushings meeting the requirements of ASTM B584, Standard Specification for Copper Alloy Sand Castings for General Applications, Alloy C86200 or Alloy C86300. Provide bearing plates and bushings from standard production. Provide bronze bearing plates and bushings with recesses completely filled with lubricating compound. Form recesses by trepanning, drilling, or the shell molding process, as shown on the P lans, but at least 3/16 inch deep. Ensure recesses have straight sides without grooves, and do not intersect the edges of the parent plate or bushing. Provide plates with recesses that are uniformly spaced in a geometric pattern over the area of the bearing, with adjacent rows overlapping in the direction of motion. Provide lubricating compound consisting of graphite, metallic substances, and a lubricant binder to form a dense, non-plastic, lubricating insert, capable of withstanding spalling and atmospheric elements . Do not use shellac or other gummy Materials as the lubricant binder. Ensure the top surface of the bearing insert is flush with or slightly above the surface of the bearing plate or bushing. For both bearing plates and bushings, provide a lubricated area that comprises 25 percent to 30 percent of the total area. If the plate or bushing manufacturer uses a bearing insert in the shape of a hollow cylinder, ensure the net lubricated area is at least 20 percent of the total area of the plate or bushing. If the Plans do not indicate which surfaces to lubricate, provide inserts for surfaces that have provisions for movement other than flexural. Provide bearing plates and bushings with contact surfaces with at least a 125 micro inch finish. Provide bearing plates that are true to detail, flat surfaces truly flat and curved surfaces curved true to the radius with an allowable working tolerance of 0.02 inches between male and female fittings. Provide a minimum net section of 1/2 inch for the bronze. Provide bushings with a wall thickness of at least 3/8 inch. Provide the machine allowances for the inside diameter and outside diameter operating fit of bushings recommended by the manufacturer unless otherwise shown on the Plans. Ensure the bronze and steel portions of bearing plates and bushings are assembled in the fabricating shop and match marked or bonded together and shipped as a unit.

3329.3SAMPLING AND TESTING — BLANK