1978/01/23 Caterpillar

Change In Design Of Engine Governor, Fuel Injection And Transfer Pump Groups, And Fuel Ratio Control Groups{1264,1278,1286}

Usage:

3408 Truck Engines;
3408, 3412 Industrial and Marine Engines;
631D, 633D, 637D Tractors;
988B Loaders

Description of Change: Several changes have been made to the basic design of the engine governor, fuel injection and transfer pump groups, and the fuel ratio control groups on the above models. With these changes, new torque control groups are used, and new solenoid shut off groups on engines so equipped.

New governor design--governor for 3408 Truck Engine shown.

The change in design is made to permit the use of a bracket assembly with a solid, one-piece lever for the connection between the vertical pin of the governor and the fuel rack. The solid lever will operate better than the two-piece lever and spring in the former bracket assembly, and will not cause restriction of fuel rack movement or other problems. The new design is similar to that used on 3406 Engines, especially in components of the fuel ratio control and solenoid shut off groups.

Some of the improvements in the new design are:

... The fuel ratio control, and shut off solenoid when used, are in a location on top of the governor. This eliminates (removes) the link formerly used between the fuel ratio control and the fuel rack, which caused problems in some conditions.

... The torque control groups used with the new governors have a different contact for the electrical continuity tester. The new contact is the same as the contact for 3406 Engines.

... A new high idle screw has an O-ring seal around the screw to hold the setting. This will hold the screw in position better than the former plastic lock, especially after the setting has been changed several times.

... A new bumper spring (see the illustration) near the top of the vertical bolt in the governor gives more clearance for the shut off lever.

... The plate, and assembled parts, between the fuel injection pump housing and the governor are now released as a separate group. This improves assembly procedures and permits easier identification of parts.

Adaptable To: The new parts are adaptable to earlier engines, but conversion is not practical because of the large number of parts needed.