Design and Materials

Cosmec’s disc bearing designs draw from experience, full-size bearing testing, and the latest technology. Our team has total design and manufacturing experience in excess of 50 years, and we participate in creating the very latest specifications.

Our designs are based on using ASTM A709 Grade 50 (AASHTO M270 Grade 50) steel and ASTM A709 Grade 50W (AASHTO M270 Grade 50W) weathering steel. ASTM A709 Grade 36 (M270 Grade 36) will be considered on demand.

The urethane discs are made from polyether urethane compound formulations that meet present AASHTO requirements or requirements mandated by specific state DOT specifications. These compounds are formulated to accommodate all design rotations without lift-off.

However, with these urethane formulations, the urethane disc will bulge under vertical load and will also exhibit “creep” over time; therefore, we find it advantageous to provide limiting rings (see Figure 2) to prevent excess slip of the disc, which can result in larger vertical deflections.

Some disc bearing manufacturers provide bearings without these limiting rings and depend solely on friction between the disc and the mating steel surfaces to control the urethane disc deformation. Cosmec does NOT recommend this variation of a disc bearing design due to the lack of consistent control of the disc deformations from bearing to bearing.

All materials for all US bearings will be certified domestic material, manufactured and fabricated in the USA in accordance with the “Buy American” requirements for all federally funded work.

Other material specifications include ASTM A240 Type 304 and Type 316 stainless steel with a #8 mirror finish; ASTM D4894 PTFE. Special high-strength shear pin material is used to ensure a smaller pin diameter and thus a smaller bearing.

Testing can be undertaken to fulfill all requirements of the AASHTO specifications and any other specialized testing as may be required. Most testing can be performed in our own testing facilities.

Coating on the bearings can be the latest high-performance paints, including high-solids zinc primers, or the bearing assemblies can be metallized (zinc or zinc/aluminum thermal spray coatings). Galvanizing of the carbon steel components can be considered on demand. Coating recommendations can be made to ensure a long-lasting product, no matter the environment.