2015/02/13 Caterpillar

Off-Highway Truck/Tractor:

793D (S/N: FDB1-UP)

Description of Change:

Note: This Service Magazine applies to any 793D Off-Highway Truck that already has the parts installed that are mentioned in Service Magazine, "A New Rear Accessory Drive is Used on Certain 3516B Off-Highway Truck Engines". The new rear accessory drive is installed at the factory on the following serial numbers: FDB01752-UP for Low Altitude Arrangements and FDB01749-UP for High Altitude Arrangements.The gear and shaft widths have increased slightly. The tooth mesh between the cluster gear and the camshaft idler gears has been improved. Lubrication for the mesh has also been provided through the shaft.

These improvements improve the service life of the gears by reducing wear.

Adaptable To: The new shaft and camshaft idler gears replace the former shaft and gears on the applications listed above. Refer to Illustration 1 and Table 1 for a list of the new part numbers, former part numbers, and the required quantities.

Illustration 1	g03791920
(1) Two 443-6069 Idler Gear As (2) 442-2324 Gear Shaft (3) 443-9634 Idler Gear As

Note: The new gear shaft or idler gear assemblies must not be used with the former shaft or gear assemblies. Mixing the new gear shaft or idler gear assemblies with the former shaft or gear assemblies will result in reduced component life.This change is effective for serial numbers FDB01839-UP.

This change is also effective on all new and remanufactured 793D Off-Highway Truck Engines built after 1April 2015.