2008/05/19 Caterpillar

Off-Highway Truck:

793D (S/N: FDB1-UP)

Service Magazine SEPD1065, 15 January 2010, "Improved Drive Shaft Groups Increase Loading Capability ". Disregard this article. See the replacement article that follows.

Description of Change: New yokes are used in the engine and the accessory drive. The new yokes are larger than the former yokes. This will allow the yokes to transfer power better than the former yokes. A new adapter is used in the engine in order to accommodate the larger size of the yokes. A new drive shaft is used. The new drive shaft contains a wall that is thicker. The new parts will improve the performance of the machines in the field.

Adaptable To:

Illustration 1	g02046520
A view of the back, right side of the engine arrangement

The new 339-6381 Yoke (1) is part of the new 350-1830 Accessory Drive Gp that superseded the former 304-5269 Accessory Drive Gp in the 235-0300 Engine Ar and the 288-4348 Engine Ar. The former 304-5269 Accessory Drive Gp used the former 301-5186 Yoke.

Table 1

Parts Needed to Update the 304-5269 Accessory Drive Gp .
Item	Qty	Part Number	Description
1	1	339-6381	Yoke
2	1	3K-5234	Hard Washer
3	1	2K-7471	Locknut
4	1	315-0633	Shaft As
5	1	341-8067	Adapter

You can update the former 304-5269 Accessory Drive Gp with the new parts. Use the parts that are listed in Table 1 in order to update the yoke in the 304-5269 Accessory Drive Gp .

Note: When you replace the former yoke, shaft assembly (4) may be damaged. If you damage shaft assembly (4) then replace the shaft assembly.The new 341-8067 Adapter (5) is a direct replacement for the former 304-4408 Adapter in the 240-7763 Flywheel Housing Adapter Gp. The 240-7763 Flywheel Housing Adapter Gp is part of the 235-0300 Engine Ar and the 288-4348 Engine Ar.

Illustration 2	g02046593
A view of the pump drive from the right side of the machine.

The new 173-5798 Yoke As (6) is part of the new 149-3060 Pump Drive Gp that superseded the former 304-6663 Pump Drive Gp in the 193-6237 Hydraulic Pump and Mounting Gp. The 193-6237 Hydraulic Pump and Mounting Gp is part of the 193-6235 Hydraulic Ar. The former 300-3304 Yoke As was part of the former 304-6663 Pump Drive Gp.

Table 2

Parts Needed to Update the 304-6663 Pump Drive Gp .
Item	Qty	Part Number	Description
6	1	173-5798	Yoke As
7	1	201-0439	Lip Type Seal

You can update the former 304-6663 Pump Drive Gp with the new parts. Use the parts in Table 2 in order to update the 193-6237 Hydraulic Pump and Mounting Gp .

Note: When you replace former yoke assembly, lip type seal (7) may be damaged. If you damage lip type seal (7) then replace the lip type seal.

Illustration 3	g02046613
A view of the drive shaft that connects the accessory drive to the pump drive group.

The new 340-0012 Drive Shaft (8) is a direct replacement for the former 300-1928 Drive Shaft in the 193-6221 Power Train Ar.

Table 3

Parts Needed to Update the 193-6221 Power Train AR .
Item	Qty	Part Number	Description
8	1	339-6380 (1)	Universal Joint Gp
9	8	0S-1604 (1)	Bolts

( 1 )

A serviced part of the 340-0012 Drive Shaft

Use the parts in Table 3 in order to update the 193-6221 Power Train Ar with the new parts. Tighten the bolts (9) to 156 ± 7 N·m (115 ± 5 lb ft).

All of the new parts must be installed together. The new parts are adaptable to machines FDB1-1203. The new parts became effective in production with the machine FDB1204-UP.