Usage:
NOTE: The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
NOTE: This Program can be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS8422" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and use "T" as the SIMS Description Code. If administered after failure, use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.
Termination Date
July 31, 1996Problem
The pins may come out of the cardan joint in the servo valve causing a loss of neutral adjustment in the hydrostatic transmission of certain 953B, 963B and 973B Loaders. The clevis pin snap rings may be incorrectly installed or missing from the lower end of the clevis pins that secure the servo cylinders to the pump swashplates.
Affected Product
Model & Identification Number
953B (5MK2132-2133, 5MK2135-2135, 5MK2146-2146, 5MK2149-2153, 5MK2156-2172, 5MK2174-2187, 5MK2189-2230, 5MK2232-2246, 5MK2248-2250, 5MK2252-2252, 5MK2254-2255, 5MK2261-2261)
963B (9BL640-640, 9BL670-674, 9BL682-682, 9BL686-686, 9BL689-689, 9BL691-692, 9BL696-696, 9BL700-700, 9BL702-722, 9BL724-751, 9BL754-763, 9BL776-776, 9BL781-781, 9BL783-783, 9BL785-786, 9BL788-790, 9BL792-793, 9BL818-818, 9BL820-820, 9BL823-823, 9BL825-825, 9BL835-835, 9BL837-838, 9BL841-842, 9BL846-846, 9BL850-850, 9BL860-860, 9BL882-882, 9BL884-884, 9BL890-890, 9BL892-892, 9BL905-905, 9BL909-909, 9BL912-912)
973 (86G3018-3019, 86G3022-3027)
Parts Needed
Action Required
See attached rework procedure.
Service Claim Allowances
NOTE: This is an 8-hour job.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.
- (1-Rework Procedure)
Rework Procedure
Replacement of servovalve cardan joint and inspection of snap ring position on the clevis pin between servo cylinder and pump swashplates.
NOTE: Refer to the Disassembly and Assembly Section of the Service Manual while performing this rework.
1. Tilt the cab to the 90° position.
2. Remove the internal hydrostatic power control unit linkage. Be careful not to change the position of the neutral screws and synch screws.
3. Use mirrors and a flashlight to check that the 2R0364 Snap Ring is on the 9J1208 Pin that connects the servo cylinders and swashplates and is in the groove.
4. If one of the snap rings is missing, call Track-Type Loader Product Support for further instructions at one of the phone numbers listed below:
NACD (309) 675-9535 or (309) 494-0817COSA (33) 76 39 71 29
5. Remove both servo valves, until you see both joint assemblies below the servo valves. Remove in one unit servo-valves, stems and linkages.
6. Remove both 6E0023 Joint Assemblies from their location. It is not necessary to remove the allen bolts and the 9J9859 Cup where the joint assembly is maintained.
7. Install new joint assemblies with their springs. Use a screwdriver to put the springs in position.
8. Install both servo valves.
9. The complete mechanical adjustment of the power control unit linkage is not necessary. Install the 6V3085 Fixture Assembly. Do not install the under speed raising tool. Do all of Step 8 in the 953 Testing and Adjusting section of the Service Manual, SENR 3193, page 101. Make sure that both spherical ball rod ends are aligned. Tighten both locknuts and remove the 6V3085 Fixture Assembly.
10. Install the top cover with a new 6E2802 Gasket on the HPCU.
Neutral adjustment
1. Put the cab in the 24° tilt position and connect the electric wiring and governor control (optional).
2. Disconnect the brake line from the transmission to brake manifold. Plug the brake line and brake manifold.
3. Pull the transmission lever into forward or reverse position to ensure brakes hold the machine before testing.
4. Turn the synch cut-off valve in and tighten the lock nut.
5. Install two 6000 psi pressure gauges to measure drive pressures on both sides.
6. Run the engine at around 1500 RPM and leave the transmission control lever in the PARK position.
NOTE: It is desired to run this test at running oil temperature (80 ± 5°C (175 ± 10 °F)).
7. Using the correct tool, reach through the cover and turn the neutral adjustment screw two clicks at a time, in either direction. Remove the tool and read the pressure gauge each time (leaving the tool in place can cause an incorrect reading). Stop when the pressure reaches and holds at 1000 psi.
8. Turn the neutral adjustment screw in the opposite direction counting each click. Turn the screw through the neutral position (indicated by the pressure reading).
9. Stop when the pressure reaches and holds at 1000 psi.
10. Split the number of click counted, turn the neutral adjustment screw back (the opposite direction) to the neutral position (one half of the counted clicks). Do the same for the other side.
11. Run the engine at high idle and repeat Steps 7, 8, 9 and 10.
12. Run test number 4 and 6 as described in the Testing and Adjusting Manual, SENR 5275, Pressure Testing and Transmission Troubleshooting Data Sheet.
13. Put the cab in the operating position, connect the linkages and brake lines and tighten the ROPS support bolts.
14. Move the machine to a smooth, level area, free of traffic. Move the governor control lever to the high idle position and run the machine over a measured distance of 30.5 M (100 feet). The maximum allowable drift is 3.65 M (12 feet).
15. Open the sync valve 3 turns and tighten the locknut.