HOUSING 1W9668 - Caterpillar

LoadersSUPPLEMENT: 09/02/85SERVICE MAGAZINE, FEBRUARY 28, 1983, PAGE 1.In the article "Improved Gears Used In Engine Rear Gear Train; Check End Play Specification," put a mark through the last two paragraphs in the article. Do not machine bearing spacers or fabricate shims for the PTO gear cage. Both of these procedures can cause excessive gear end play. This can result in shortened bearing life, abnormal gear wear and shortened life of driven components, due to PTO shaft orbit. The correct information follows. The PTO and idler gears use bearings that are manufactured to tolerances which insure correct gear end play. No end play measurements are required and no shims are provided for adjustment.
Use the procedure given in the Service Manual to install the new gears. The new PTO and idler gears should turn freely, by hand, after installation. If new idler gear bearings are installed, use a 6V7725 Bearing Assembly as described in the APRIL 2, 1984, SERVICE MAGAZINE, PAGE 2, article "New Bearing Assembly Used In Rear Gear Groups".
--------------- END SUPPLEMENT ---------------Description of Change: There have been some problems with failure of rear gears in engines for 992C Loaders. These gears are used to operate the machine hydraulics and steering system. Improved gears are now used in the rear gear group. With the former gears, the gradual development of cracks was possible under the gear teeth. This caused separation of the teeth and failure of the hydraulic and steering system.
The new idler gear, crankshaft gear, and PTO (power take-off) gear are heat treated and hardened by a different method than the former gears for better wear resistance and longer service life.
Adaptable As: The new 2W3997 Idler Gear, 2W3996 Crankshaft Gear, and 2W3998 PTO Gear are direct replacements for the former 8N795 Idler Gear, 8N797 Crankshaft Gear, 8N798 PTO Gear. The new gears are in effect on 992C Loaders with Engine Serial Number 73W3714. It is important to check the amount of end play (front-to-rear movement) of the 2W3998 PTO Gear and the 2W3997 Idler Gear when these gears are installed.
End play for the 2W3998 PTO Gear must be between 0.23 mm (.009") and 0.81 mm (.032"). End play for the 2W3997 Idler Gear must be between 0.18 mm (.007") and 0.58 mm (.023").