SHAFT-GOVERNOR CONTROL 6Y4821 - Caterpillar

All Engines Equipped With AiResearch Model TV81 TurbochargersSUPPLEMENT: 08/23/82SERVICE MAGAZINE, JUNE 14, 1982, PAGE 3.In the article, "Stronger Turbine Wheel Used In Turbocharger Shaft And Wheel Assemblies", change the last paragraph to read as follows: The improved part has been put in effect first on 3406 Truck Engines, with Serial Numbers 92U55635. It is adaptable to TV81 Turbochargers on 3406 Truck Engines 92U13178-Up. Other "In Effect" serial numbers are not yet available.
--------------- END SUPPLEMENT ---------------Description of Change: The turbine wheel used in shaft and wheel assemblies for AiResearch Model TV81 Turbochargers is now made of a stronger material. This will prevent turbocharger failures which can be caused by a broken turbine blade in some specific load conditions. Formerly, it was possible for some conditions to cause a vibration stress which broke one blade of the turbine wheel. This destroyed the balance of the shaft assembly, and the result was heavy damage to the turbocharger bearings and other parts.Adaptable As: Direct replacement. The part numbers of the 6N4606 and 9N2043 Turbine Shaft And Wheel Assemblies did not change. Identification of the improved part can be made by a number "4" on the nose piece of the turbine wheel. The improved part has been put in effect first on 3406 Truck Engines, with Serial Numbers 92U55635-Up. It is adaptable to TV81 Turbochargers on 3406 Truck Engines 92U13178-Up. Other "In Effect" serial numbers are not yet available.