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© 2022 Eaton Cummins Automated Transmission Technologies. All rights reserved
2022.10.7
Timing Procedures | General Information TRSM0940
Timing Procedures
It is essential that both Counter Shaft assemblies of the
front and auxiliary sections are timed. This ensures proper
tooth contact is made between Main Shaft gears seeking to
center on the Main Shaft during torque transfer and mating
Counter Shaft gears that distribute the load evenly. If not
properly timed, serious damage to the transmission is likely
to result from unequal tooth contact, causing the Main
Shaft gears to climb out of equilibrium.
Timing is a simple procedure of marking the appropriate
teeth of a gear set prior to installation and placing them in
proper mesh while in the transmission. In the front section,
it is necessary to time only the drive gear set. Depending on
the model, only the low range, deep reduction or splitter
gear set is timed in the auxiliary section.
Front Section
1. Clearly mark the tooth located directly over the
drive gear keyway as shown prior to placing each
Counter Shaft assembly into the case, This tooth is
stamped with an “O” to aid identification.
2. Mark any two adjacent teeth on the Main Drive
Gear.
3. Mark the two adjacent teeth located directly oppo-
site the first set marked on the Main Drive Gear.
There should be an equal number of unmarked
gear teeth on each side between the marked sets.
4. After placing the Main Shaft assembly into the
case, the Counter Shaft Bearings are installed to
complete installation of the Counter Shaft assem-
blies. This meshes marked Counter Shaft drive gear
teeth with marked Main Drive Gear teeth.
When installing the bearings on the left Counter Shaft,
mesh the Counter Shaft drive gear marked tooth with either
set of Main Drive Gear two marked teeth.
Repeat the procedure when installing the bearings on the
right Counter Shaft; make use of the remaining set of Main
Drive Gear two marked teeth to time the assembly.
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