TRANSMISSION AR 3844149 - Caterpillar

Illustration 1. Changes 2, 5 and 6-governor.3. The fuel ratio control is changed as follows (Illustration 3): a. A bevel is added to the end of the control lever which makes contact with the fuel rack. This prevents possible contact between the lever and the fuel injection pump housing to make sure the lever operates freely.b. The spring preload is decreased so it will give less resistance to the opposite force of the spring in the control linkage.c. A.141" (3.57 mm) diameter hole added to the bottom of the bracket fits on a new slotted pin installed in the fuel pump housing. This prevents rotation of the bracket when the mounting bolt is tightened, and keeps the lever in correct alignment with the housing.4. The fuel injection pump housing is changed to increase the thickness of the mounting boss and add a slotted pin for alignment of the fuel ratio control bracket. See Illustrations 4, and 5 or 6. The thicker mounting boss will prevent possible cracks in this area.5. An increased spring preload is used in the linkage between the governor and fuel rack to give more positive operation, especially in conditions which cause a high resistance to movement. Illustration 1.6. The governor control pin is now made of an alloy steel with higher strength to prevent possible cracks in the upper flange (.468"-11.80 mm diameter), and increased hardness for longer service life. Illustration 1.
Illustration 2. Changes 12 and 13-governor.
Illustration 3. Change 3-Fuel ratio control bracket assembly.
Illustration 4. Changes 4 and 8-Fuel injection pump housing.
Illustration 5. Changes 4 and 7-Fuel injection pump housing for 3408 Engines.7. The surface area of the camshaft bearings is increased to extend bearing service life. Dimensions to install the new bearings are shown in Illustrations 5 and 6.8. The bearings for the governor drive pinion are now longer to give more bearing surface, and the chamfer is removed from the outside diameter at one end. See Illustration 4. Removal of the chamfer improves the pump discharge pressure.9. The governor shut-off lever has improved material specifications for more strength and better resistance to impact stresses. Illustration 7.
Illustration 6. Changes 4 and 7-Fuel injection pump housing for 3412 Engines.
Illustration 7. Changes 9 and 10-Governor control levers.
Illustration 8. Change 11-Shut-off solenoid.10. Self-locking bolts are now used to hold all levers to the shut-off shaft. Illustration 7. Formerly, it was possible for vibration to loosen the bolts.11. The electric shut-off solenoid now has a wider slot (notch) in the end of the shaft where it makes contact with the shut-off lever. See Illustration 8. This prevents side loads that can break the lever in some conditions.12. A shorter right rear bolt is used to hold the governor cover to the governor housing. See Illustration 2. Formerly, it was possible for the bolt to make contact with the governor lever and limit the high idle.13. Since the speed limiter has been removed (disconnected on earlier governors), the later governors are not machined for the speed limiter. Illustration