REDESIGN OF TAINTER GATE TRUNNION BEARINGS TUTTLE CREEK LAKE PROJECT - MANHATTAN, KANSAS

摘要

Turtle Creek Dam, located in Manhattan, Kansas is currently undergoing major rehabilitation to the embankment. To be included in the major rehab is structural modification of the tainter gates, media blasting and re-painting of the 18 tainter gates and associated operating equipment that are used for making emergency releases in the emergency spillway. Current Corps criteria for tainter gate trunnion bearings require use of a 0.3 friction factor for the sliding components. When designed in the 1950's, the Corps criteria did not have the 0.3 friction factor requirement. The 0.3 friction factor requirement was mandated due to historical tainter gate performance. Structural analysis of the Tuttle tainter gates per Corps EM 1110-2-2702 criteria revealed that the strut arms are deficient when the load created by the 0.3 friction factor is present. The trunnion bearing assemblies were subsequently investigated for load bearing capacity and were deemed adequate. However, some of the mechanical aspects of the bearings were questionable. The operations and maintenance (O & M) drawings showed a surface finish of 125 for all critical interference fits as well as all critical sliding surfaces for the bearing and pin. This seemed an unusually rough surface finish for these critical components. Further investigation showed the interference fit between the bearing and the bearing arm did not comply with current machining standards. Since no dowel pin was used to lock the bearing in position relative to the bearing arm, rotation of the bearing in the arm was suspected. There were no known problems with any of the bearings since original construction of the spillway gates. The only time the gates were operated under load was during The Flood of 1993. A procedure was written to determine if any of the 36 bearings had rotated out of position. Maintenance personnel at Tuttle Creek Lake performed the inspection for each bearing. The inspection was extremely valuable, verifying that one bearing had indeed rotated out of position. Redesign of the trunnion bearings would be required. The new design would eliminate the possibility of bearing rotation within the bearing arm, reduce the friction between the bearing and the pin and reduce the friction between the bearing arm and side thrust washers. The new design would significantly reduce the friction within the trunnion bearing, thereby reducing the load transferred from the bearing into the bearing arms.