1994/02/07 Caterpillar

New Pinion And Seal Assembly Replaces The Former Carbon Seal{3280,3254,3250}

Usage:

784B (5RK) Tractors;
785 (8GB),
785B (6HK),
789 (9ZC),
789B (7EK),
793 (3SJ),
793B (1HL) Trucks

SUPPLEMENT: 05/08/95

Service Magazine, February 7, 1994, Page 10, "New Pinion And Seal Assembly Replaces The Former Carbon Seal" for 784B Tractors; 785, 785B, 789, 789B, 793, 793B Trucks.

The former part no. 5T-5979 Seal in the parts for 793 and 793B Trucks is incorrect. The correct former part no. is 7X-4779 Seal.

--------------- END SUPPLEMENT ---------------

Description of Change: A new pinion assembly and seal assembly is being used to improve the seal service life. The former carbon seal has been replaced with a lip seal that utilizes a wear sleeve on the pinion.

Adaptable To: The new pinion assembly and seal assembly are effective with 784B (5RK13) Tractor, 785B (6HK226), 789B (7EK232) and 793B (1HL90) Trucks. The new parts, when used together, are a direct replacement for the former parts shown in Chart A.

In some cases where the differential has been disassembled and the pinion shows no signs of wear or damage, the pinion can be modified to accept the wear sleeve for the new lip-type seal. Use the following illustrations and dimensions to modify the pinion.

Illustration 1. Pinion modification for 784B Tractors, 785 and 785B Trucks

Illustration 2. Pinion Detail A.

Illustration 3. Pinion modification for 789, 789B, 793 and 793B Trucks.

Pinion Detail B.

Caterpillar Information System:

1994/02/07 Cover Assembly Protect Hydraulic Tank Sight Glasses{5056}

1994/02/07 New Radio Mount Available For B Series Backhoe Loaders Equipped With Air Conditioning{7338}

1994/02/07 New Radiator Hose Clamp Allows Easier Tightening{1380}

1994/02/07 Lock Valve Group With A Relief For Right Blade Lift Cylinder Is Available On Motor Graders{5102,5100}

1994/02/07 New Hose Clamps Provide Improved Clamping{1058}

1994/02/07 Screened Fitting for Implement Motor Case Drain Return Line Available{5720,4351,4921}

1994/01/31 Automatic Shut-Off Systems Not Recommended on Mobile Earthmoving Equipment {7418,7403}

1994/01/31 Air Conditioners Use R134a Refrigerant {7300}

1994/01/31 New Transmission Cooler Group Used {1375}

1994/01/31 New Longer Fan Adapter Used On Replacement Engine {1359,1356}

1994/01/31 New Torque For Transmission To Differential And Differential To Rear Housing Bolts {3250,3258}

1994/01/31 New Transmission Shift Solenoid Valve Resists Cracking {3174}

1994/02/07 New Wheel Bearing Adjustment Procedures{4208}

1994/02/07 Sump Guard Assembly (Crankcase Guard) Is Deeper And Has Thicker Material To Improve Clearance And Resist Bending{7151}

1994/02/07 Suspension Control Valve Mounting Group Bolt Torque Specification Is Reduced To Prevent Control Valve Sticking And Scuffing{7214}

1994/02/07 New Magnetic Drain Plug For Vibratory Bearing Reservoir Provides Early Warning Of Wear{6606}

1994/02/07 New Piston Body Has Improved Bonding Between Iron Band And Aluminum Body{1214}

1994/02/07 Longer Grease Hose Assembly Used In Fan Belt Tightener Groups{1358,1359}

1994/02/07 12 And 24 Volt DC Work Lights Are Available{0600}

1994/02/07 New Turbocharger Groups And New Turbocharger Cartridge Groups Have Improved Thrust Bearing And Turbine Ring Seal{1052,1053}

1994/02/07 Cylinder Head Gaskets Improved To Provide Better Fire Ring Retention{1124}

1994/02/07 Fuel Injection Pump Improvements{1251}

1994/02/14 Multipurpose Tractor Oil (MTO) Is Usable In All Challenger Implement Hydraulic And Combined Implement And Steering Hydraulic Systems{5068,5050,5450}

1994/02/14 Air-To-Air Aftercooler Assembly Mounting Brackets Improved{1063}