Usage:
CONFIDENTIAL TIBU4673-00
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TECHNICAL INFORMATION BULLETIN |
December 1, 2005 |
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Off Highway Trucks |
793 (1HL, 4AR, 4GZ, ATY) |
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1207 |
SUBJECT: Premature Wear of the Accessory Drive Thrust Washer on 793 Off Highway Truck Engines
PROBLEM:
The thrust washers for the accessory drive on some Off Highway Truck Engines have been wearing prematurely. The main cause of the wear is the lack of lubrication to the thrust washer.
SOLUTION:
The above problem continues to be investigated. In the interim, Caterpillar recommends the following:
The 7N-8525 Thrust Washer must be modified to include one additional hole that allows for pressurized oil to be supplied to the surface of the thrust washer. This will improve the service life of the thrust washer. The thrust washer must also be modified to include an additional hole for a dowel.
In order to use the modified thrust washer, the 141-7130 Adapter Assembly must be modified to include an oil passage that will allow pressurized oil to lubricate the surface of the thrust washer. Refer to Illustration 1. The adapter must also be modified to include two 3F-6795 Dowels that will hold the modified thrust washer in the correct position.
Illustration 1 (1) Oil passage
Main Oil Hole Location and Dimensions
Threaded oil hole (2) is a number 6 port. A port contour cutter is needed to create the correct hole profile that is necessary for the O-Ring seal. Refer to Illustration 2, Illustration 3, Illustration 4 and Table 1.
Illustration 2 Port contour cutter
Illustration 3 (2) Threaded oil hole (A) Center of hole to center line of the adapter (B) Center of hole to center line of the adapter
Illustration 4 (C) Thread size and pitch (D) Diameter of drilled hole (E) Depth of drilled hole (F) Depth of threads
Table 1
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Threaded Oil Hole (2) |
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A |
B |
C |
D |
E |
F |
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23 mm (0.9055 inch) |
53 mm (2.0866 inch) |
9/16 ? 18 |
12.2 mm |
20.5 mm (0.8070 inch) |
13.5 mm (0.5314 inch) |
Thrust Washer Oil Hole
Illustration 5 (3) Thrust washer oil hole (G) Center of hole to center line of the adapter (H) Center of hole to center line of the adapter
Illustration 6 (I) Depth of hole (J) Diameter of hole
Table 2
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Thrust Washer Oil Hole (3) |
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G |
H |
I |
J |
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23 mm (0.9055 inch) |
32.7 mm (1.2873 inch) |
25 mm (0.9843 inch) |
5 mm (0.1968 inch) |
Oil Cross Passage
Illustration 7 (4) Oil cross passage (K) Diameter of oil cross passage (L) Angle of oil cross passage (M) Distance from adapter center line to center line of cross passage
Table 3
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Oil Cross Passage (4) |
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K |
L |
M |
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3.25 mm (0.1279 inch) |
57 degrees |
55.5 mm (2.1850 inch) |
Adapter Dowel Locations
Illustration 8 (5) Holes for 3F-6795 Dowels (N) Dimension form the centerline of the dowel hole to the centerline of the adapter (O) Dimension form the centerline of the dowel hole to the centerline of the adapter (P) Dimension form the centerline of the dowel hole to the centerline of the adapter (Q) Dimension form the centerline of the dowel hole to the centerline of the adapter
Illustration 9 (R) Diameter of dowel holes (S) Depth of dowel holes
Table 4
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Holes for 3F-6795 Dowels (5) |
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N |
O |
P |
Q |
R |
S |
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22.9 mm (0.9015 inch) |
34.3 mm (1.3503 inch) |
40.5 mm (1.5944 inch) |
8.1 mm (0.3188 inch) |
4.577 ± 0.013 mm (0.1794 ± 0.0005) inch |
7.5 ± 0.5 mm (0.2952 ± 0.0196 inch) |
The installed height of the 3F-6795 Dowels must not exceed 3.5 mm (0.1377 inch).
Thrust Washer Modifications
Illustration 10 (6) Existing Hole (7) New oil hole (8) Unused existing hole (9) New dowel hole (T) Dimension for the centerline of the existing holes to the centerline of the new oil hole (7) (U) Dimension from the centerline of the existing holes to the centerline of the new oil hole (7) (V) Dimension from the centerline of the existing holes to the centerline of the new dowel hole (9) (W) Dimension from the centerline of the existing holes to the centerline of the new dowel hole (9)
The current 5.5 mm (0.2165 inch) diameter hole (6) in the 7N-8525 Thrust Washer is reused. Existing hole (8) is not used. Two additional holes must be drilled in the thrust washer. The first hole (9) is 4.587 mm (0.1805 inch) in diameter. This hole is for a dowel. The second hole (7) is 6 mm (0.2362 inch) in diameter. This hole is for the new oil passage. Refer to Illustration 10 and Table 5.
Table 5
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Thrust Washer Hole Dimensions |
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T |
U |
V |
W |
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39.95 (1.5728 inch) |
0.92 mm (0.0362 inch) |
38.11 mm (1.5003 inch) |
15.77 mm (0.6208 inch) |
Hose Assembly
A 282-9627 Hose Assembly will supply the oil from the oil gallery to an 8M-0506 Connector and a 6V-5049 O-Ring that are threaded into the modified adapter. Refer to Illustration 11.
Illustration 11 (10) 2W-7226 Adapter (11) 3R-5387 Connector (12) 0S-1590 Bolt (13) 5M-2894 Hard Washer (14) 9L-4234 Spacer (15) 3S-8665 Clip (16) 282-9627 Hose As
Route the 282-9627 Hose Assembly as shown in Illustration 11. Ensure that the hose is secure.
Note: The 282-9627 Hose Assembly is a not stocked in the Morton Parts System. Refer to Hydraulic Information System (HIS) for build information.
Plate Assembly
The 5T-4136 Plate Assembly must be modified so that the connector for the 282-9627 Hose coupling can be installed. Refer to Illustration 12 and Illustration 13.
Illustration 12 Modified 5T-4136 Plate Assembly
Illustration 13 (16) 282-9627 Hose (17) 8M-0506 Connector (18) Modified section (19) 5T-4136 Plate assembly (20) Modified 141-7130 Adapter As
Guard
The 211-1152 Guard must be modified so that the hose assembly can pass through the slot in the top of the guard. The slot the top of the guard must be enlarged from 20 mm (0.7873 inch) (X) to 63 mm (2.50 inch) (Y). Refer to Illustration 14 through Illustration 16.
Illustration 14 (X) Edge of existing slot in the guard (Y) Edge of expanded slot in the guard
Table 6
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Slot Dimensions |
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X |
Y |
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20 mm (0.7873 inch) |
63 mm (2.50 inch) |
Illustration 15
Illustration 16
Table 6
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Required Parts |
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Quantity |
Part Number |
Description |
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1 |
Thrust Washer |
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1 |
Adapter As |
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1 |
Hose As |
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1 |
O-Ring Seal |
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1 |
Connector |
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2 |
Dowel |
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2 |
Bolt |
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2 |
Spacer |
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2 |
Clip |
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1 |
Connector |
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2 |
Hard Washer |
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ALL RIGHTS RESERVED