PLANETARY GP-TRANSMISSION 2201403 - Caterpillar

776B Tractors;
777B, 785, 789 Trucks;
3500 Family Of EnginesSUPPLEMENT: 02/24/92Service Magazine; May 13, 1991; Page 20; "Rear Gear (Cam Drive) Groups Improved" for D11N, 776B Tractors; 777B, 785, 789 Trucks; 3500 Family of Engines.In the Adaptable To: The rear gear train article described that the cylinder block has been changed to accept the larger bolts. The new block part numbers were not shown in this article. The old blocks can be salvaged, reference SEBF8166, "Salvage Procedure For Bolt Holes In Block For Idler Gear Shafts In Rear Gear Train 3500 Family Of Engines."
See chart for the list of new block part numbers.
--------------- END SUPPLEMENT ---------------SUPPLEMENT: 08/26/91Service Magazine; May 13, 1991; Page 20; "Rear Gear (Cam Drive) Groups Improved" for D11N, 776B Tractors; 777B, 785, 789 Trucks; 3500 Family Of Engines.In Chart A under the column titled "Model", put a mark through 776B and 777B. The changes to the carburized gears did not take effect on these two models until the serial numbers listed in Chart B. Also, in Chart B, add the serial number "67Z829" for 3512 Generator Set (Slow Speed).
--------------- END SUPPLEMENT ---------------SUPPLEMENT: 07/08/91Service Magazine; May 13, 1991; Page 20; "Rear Gear (Cam Drive) Groups Improved" for D11N, 776B Tractors; 777B, 785, 789 Trucks; 3500 Family Of Engines.In the Adaptable To: section, add the following Note.
The new gears and gear assemblies when used together, along with the other new parts, including the cylinder block modification, are replacements for the former gears and gear assemblies. DO NOT MIX the new shafts, bearings, or gear assemblies with the former shafts, bearings, or other gear assemblies. Since the new shafts are slightly larger in diameter than the former shafts, a former gear assembly bearing used on a new shaft may not have enough clearance for adequate oil film thickness. The former bearings, thrust plates, washers, bolts, etc., are still available for parts service if the gears or shafts are not changed.--------------- END SUPPLEMENT ---------------Reference: Guideline For Salvage Operations, SEBF8166, "Salvage Procedure For Bolt Holes In Block For Idler Gear Shafts In Rear Gear Train 3500 Family Of Engines."Description of Change: Several changes have been made to the 3500 Family Of Engines which will improve the service life and reliability of the rear gear groups. These improvements include: - New cam drive gears, idler gears, and cluster gears now have a deeper case depth of hardened material (carburized).- The sleeve bearings in the cluster gears and idler gears have been changed from steel-backed aluminum bearings to steel-backed bronze bearings. This will increase the bearings fatigue resistance.- The cluster and idler gear shafts are slightly larger in diameter. This reduces the clearance between the shaft and the sleeve bearings to minimize gear wobble.- New cluster and idler gear shafts have two smaller oil supply holes instead of just one large diameter hole. This will provide better distribution of the oil to the bearing.- Idler gear shafts have a thicker flange to prevent breakage at the corners of the half flange.- The bolts