Hoist Cylinder Hydraulic Circuit Needs To Be Reworked On Certain 785 And 785B Trucks Caterpillar


Hoist Cylinder Hydraulic Circuit Needs To Be Reworked On Certain 785 And 785B Trucks

Usage:

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Caterpillar: Confidential Yellow

NOTE: This Program must be administered as soon as possible. When reporting the repair, use "PI1330" as the Part Number, "7751" as the Group Number, "56" as the Warranty Claim Description Code and "T" as the SIMS Description Code. Exception: If the repair is done after failure, use "PI1330" as the Part Number, "7751" as the Group Number, "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.

NOTE: This Revised Service Letter replaces the July 19, 1997 (Revised September 1997) Service Letter. Changes have been made to the Rework Procedure.

Problem

When the truck body is being lowered to the frame and the lever is in the power down mode, then hydraulic oil pressure can be trapped in the line between the counterbalance valve and the hoist cylinder on certain 785 and 785B Trucks. The trapped oil may result in a spray of high pressure oil if the line is loosened.

Affected Product
Model & Identification Number

785 (8GB223-405 (If updated per 10-29-90 Service Magazine / Special Instruction SEHS9167) 8GB406-697 ) (All)

785B (6HK1-697)

Parts Needed

Dealers will need to order parts for this Program.

3 - 3J1907 Seal-O-Ring
1 - 4J0520 Seal-O-Ring
1 - 4J0527 Seal
1 - 6J1218 Adapter
1 - 1P3706 Seal-Rectang
4 - 8T9377 Bolt
4 - 8T9389 Bolt
5 - 6V8397 Seal-O-Ring
1 - 6V8636 Connector
2 - 6V8724 Elbow-Face
4 - 7X0325 Bolt
1 - 8X6178 Hose As.
2 - 1110287 Hose As.
1 - 1297520 Tee-Orp.
1 - 1422891 Adapter
1 - 1422988 Tee-Swivel
1 - 1424908 Adapter

Action Required

See the attached procedure.

Owner Notification

U.S. and Canadian owners will receive the attached Owner Notification.

Service Claim Allowances

NOTE: This is a 3-hour job.

NOTE: U.S. and Canadian Dealers Only - Eligible dealers may enter a Type 2 SIMS Report.

Parts Disposition

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

NOTE: MAKE EVERY EFFORT TO COMPLETE THIS PROGRAM AS SOON AS POSSIBLE.

Attach.

(1-Owner Notification)
(2-Rework Procedure)

Copy Of Owner Notification FOr U.S. And Canadian Owners

Rework Procedure

Refer to the Service Manual as necessary. Prepare the machine by draining the oil from the hydraulic tank. Make sure all the pressure in the hydraulic system has been released before disconnecting any oil lines.

NOTE: (Change to Step 12).

1. Disconnect 8X8200 Hose As. from 1159210 Tube As. on the 8W4446 Oil Cooler Line Gp. and install 6J1218 Adapter and 4J0527 Seal using new (4) 7X0325 Bolts and existing Washers.

2. On the 8W4444 Hoist Oil Lines Group install 6V8724 Elbow and 3J1907 Seal into the 6J1218 Adapter.

3. Connect 8X6178 Hose As. and 6V8397 Seal into the 6V8724 Elbow.

4. Remove (4) 5S7382 Bolts and 8X3730 Hose As. from the 9T9898 Valve and install 1422891 Adapter and 4J0520 Seal with (4) 8T9377 Bolts and existing washers.

5. Install 6V8636 Connector and 3J1907 Seal into port on side of the 1422891 Adapter.

6. Install 1422988 Tee and 6V8397 Seal into 6V8636 Connector.

7. Install Hose Assemblies 111-0287 and 8X6178 with 6V8397 Seals on the 1422988 Tee.

8. Remove 9R4005 Hose As., 6V9836 Tee, and 8T1779 Connector from the 5T6469 Flange at the hydraulic tank and install 6V8724 Elbow and 6V8397 Seal into 5T6469 Flange and reconnect 8W3273 Hose As.

9. Remove 8W5131 Hose As. and (4) 5P2566 Bolts at the hydraulic tank.

10. Install 1424908 Adapter and 1P3706 Seal with the new (4) 8T9389 Bolts and reconnect the 8W5131 Hose As.

11. Install 1297520 Tee and 3J1907 Seal into port on side of 1424908 Adapter.

12. Connect both 1110287 Hoses with 6V8397 Seals to 1297520 Tee.

13. Check for loose fittings and bolts.

14. Fill hydraulic tank to the proper oil level.

Caterpillar Information System:

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