DISC-FRICTION 6Y7970 - Caterpillar

3406, 3408 Industrial and Truck Engines;
3408 and 3412 Marine Engines (28V, 99U, 60M)Description of Change: Soft washers and lockwashers are now used with the mounting bolts for the air fuel ratio control on the above engines. The change was made to prevent contact between the mounting bolt and the shut-off shaft and still have enough threads for the bolt to engage correctly. Also, another change was made in 3406 Engines: The same mounting bolt that is used on 3408 and 3412 Engines is now used on 3406 Engines to give enough thread contact when the bolt is tightened. The bolt used formerly on 3406 Engines was shorter, and when the bolt was tightened it was possible for the threads to become damaged because very few threads were engaged.Adaptable To: These changes are adaptable to all 3406, 3408, and 3412 Engines that have the air-fuel ratio control installed on the governor. These changes are not adaptable to 3408 and 3412 Engines that have the air-fuel ratio control installed on the fuel injection pump housing. The new parts are shown in the chart that follows: