Eaton AT-1202 Transmission Service Manual

Eaton AT-1202 Transmission Service Manual
Eaton AT-1202 Transmission

Eaton AT-1202 Transmission Repair Manual
The following maintenance checks can be made without removing the transmission from the chassis. Items 1 through 5 can be performed without any prior mechanical work; items 6 through 8 require the dropping of the output driveline and the input driveline where possible.

Tool Reference
Some illustrations in this manual show the use of specialized maintenance tools. These tools are recommended for transmission repair as they make repair easier, faster, and prevent costly damage to such critical parts as bearings and sleeves.

Torque Ratings
Recommended torque ratings, location and thread sizes of capscrews and nuts are listed below. Capscrew lengths are given for reference purposes as a guide for installation at proper locations. Correct torque application is extremely important to assure long transmission life and dependable performance. Over-tightening or undertightening can result in a loose installation and in many instances, cause damage to transmission gears, shafts and bearings. Do not torque capscrews dry.

Eaton AT-1202 Transmission Workhsop Manual
Important: Read this section before starting the detailed disassembly procedures. It is assumed in the detailed disassembly instructions that the transmission has been removed from the chassis, the lubricant has been drained, the parking brake removed, if so equipped, and both universal joint companion flanges have been removed. Follow each procedure closely in each section, making use of both the text and pictures. Use certain precautions, as listed below, during disassembly.

  • Cleanliness: Provide a clean place to work. It is important that no dirt or foreign material enters the unit during repairs. The outside of the unit should be carefully cleaned before starting the disassembly. Dirt is abrasive and can damage highly polished parts such as bearings, sleeves, and bushings.
  • Bearings: Carefully wash and re-lubricate all bearings as removed and protectively wrap until ready for use. Remove all bearings with pullers designed for this purpose. Do not remove bearings with hammer and punch.
  • When Driving: Apply force to shafts, bearings, and housings with restraint. Movement of some parts is restricted. Do not apply force after the part being driven stops solidly. Use soft hammers, soft bars, and mauls for all disassembly work.

Inspection and General Instructions for Reassembly
Before reassembling the transmission, the individual parts should be carefully checked to eliminate those damaged from previous service. This inspection procedure should be carefully followed to insure the maximum of wear life from the rebuilt unit. The cost of a new part is generally a small fraction of the total cost of downtime and labor, should the use of a questionable part make additional repairs necessary before the next regularly scheduled overhaul.

Recommended inspection procedures are set forth in the check list which follows:

  • Wash all bearings in clean solvent. Check balls, rolls, and races for pits and spalled areas. Check the bearing shields for damage. Replace bearings which are pitted, spalled, or damaged.
  • Lubricate bearings and check for axial and radial clearances. Replace the bearings with excessive clearances.
  • Check fits of the bearings in the case bores. If the outer races turn freely in the bores, the case should be replaced.


  • Check the operating gear teeth for pitting on the tooth faces. Gears with pitted teeth should be replaced.
  • Check all engaging gear teeth both internal and external. Gears with teeth worn, tapered, or reduced in length from clashing in shifting should be relpaced.
  • Check the radial clearance of the bushed gear. If excessive radial clearance is found, replace the bushing.

Make sure the interior of the case and the other housings are clean. It is important that dirt be kept out of the transmission during reassembly. Dirt is abrasive and can damage polished surfaces of sleeves, bushings, and bearings. Use certain precautions, as listed below, during reassembly.


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