New Bearings Need To Be Installed On The Output Transfer Idler Gear On Certain 836 Compactors Caterpillar

New Bearings Need To Be Installed On The Output Transfer Idler Gear On Certain 836 Compactors

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Caterpillar: Confidential Yellow

NOTE: The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

NOTE: This Program must be administered as soon as possible. When reporting the repair, use "PI3789" as the Part Number, "7751" as the Group Number, "56" as the Warranty Claim Description Code and "T" as the SIMS Description Code. Exception: If the repair is done after failure, use "PI3789" as the Part Number, "7751" as the Group Number, "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.

Completion Date

February 29, 1996

Termination Date

August 31, 1996

Problem

The 1P7834 and 1P7835 Tapered Bearings that support the idler gear in the 8E9829 Output Transfer Gear Group may fail on certain 836 Compactors.

Affected Product
Model & Identification Number

836 (3RL26-95)

Parts Needed

Dealers will need to order parts for this Program.

2 - 8C3075 Seal-Lip Type

2 - 5D7449 Cup-Roller Bearing

1 - 3F5792 Seal-O-Ring

1 - 5F0149 Seal-O-Ring

2 - 5F1248 Cone-Roller

1 - 2H2665 Seal-O-Ring

2 - 2H3933 Seal-O-Ring

1 - 5J1086 Seal-O-Ring

1 - 2K4472 Seal-O-Ring

1 - 7L2181 Seal-O-Ring

1 - 7M8485 Seal-O-Ring

2 - 3P6372 Cup-Roller Bearing

1 - 5P2587 Seal-O-Ring

2 - 5P5863 Cone-Roller Bearing

1 - 6V6640 Sealant

1 - 6Y6328 Shim Pack

1 - 6Y6329 Shim Pack

1 - 1232997 Cage Assembly-Bearing

1 - 1235298 Cage-Bearing

NOTE: If the 1232997 Cage Assembly-Bearing or 1235298 Cage-Bearing are not available, the existing cages can be reworked according to the attached rework procedure.

Action Required

See the attached procedure.

Owner Notification

U.S. and Canadian owners will receive the attached Owner Notification.

Service Claim Allowances

NOTE: This is a 40-hour job.

NOTE: U.S. and Canadian Dealers Only - This Program does not qualify for a Type 2 SIMS Report.

Parts Disposition

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

NOTE: MAKE EVERY EFFORT TO COMPLETE THIS PROGRAM AS SOON AS POSSIBLE.

Attach.

(1-Owner Notification)

(2-Rework Procedure)

Copy Of Owner Notification For U.S. And Canadian Owners

Rework Procedure

1. Order the parts listed under Parts Needed.

2, Remove transmission arrangement from machine.Remove output transfer gear group from the transmission arrangement, and disassemble it.

3. Machine the following parts as shown in the associated Illustrations.

Illustration 1:

3T6176 Transfer Gear (top gear)

Illustration 2:

3T6179/1024563 Transfer Gear (idler gear)

Illustration 3:

6Y6324 Transfer Case Assembly

Illustration 4:

6Y6326 Bearing Cage (idler gear) (if 1232997 is not available)

Illustration 5:

6Y6327 Bearing Cage (top gear) (if 1235298 is not available)

4. Assemble the transfer gear group according to Service Manual procedures, except for the end play settings.

5. Prepare to make the tapered bearing settings as follows:

A. Install the top gear bearing cage without the shim pack, and install the idler gear bearing cage without either the shim pack or O-ring.

B. Install two bolts with washers 180 degrees apart in each cage, and tighten the bolts finger tight.

C. Remove the paint from the Transfer Case Cover in four areas adjacent to the retaining bolts just installed. Also insure that paint does not extend beyond the shim pack surface of the bearing cages.

D. Tighten the two cage bolts in the top cage alternately to a torque of 40 N·m (30 lb-ft). Rotate the gears. Alternately tighten the bolts to 40 N·m (30 lb-ft) again and rotate the gears until the bolt torque remains at 40 N·m (30 lb-ft) after the gears have been rotated. (This step will insure that the cups and cones are fully seated against their respective shoulders.) Loosen the bolts and reset them finger tight.

E. Repeat Step D on the idler gear cage.

6. Determine the proper shim pack thickness for the top transfer gear cage as follows:

A. Tighten the two cage bolts alternately in small, uniform increments until bolt torque is 20 N·m (15 lb-ft).

B. Rotate the gears three full turns (or oscillate an equivalent amount.

C. Repeat Steps A and B until bolt torque remains at 20 N·m (15 lb-ft) after rotation.

D. Measure and record the gap between the flange of the bearing cage and the surface of the case cover at two locations 180 degrees apart (in the paint-free areas adjacent to the cage bolts). A TAPERED FEELER GAGE IS HIGHLY RECOMMENDED FOR THESE MEASUREMENTS FOR BOTH SPEED AND ACCURACY.

E. Find the average of the two readings taken in step D) and add 0.016 inch. This total is the required shim pack thickness to produce a nominal 0.002 inch end-play. DO NOT RELY ON END-PLAY MEASUREMENTS FOR VALIDATION OF BEARING SETTINGS. SEE ITEM 9, BELOW.

F. Size and install the shim pack, install the cage and all of the retaining bolts and washers, and torque the bolts to 100 ± 15 lb-ft.

7. Determine the proper shim pack thickness for the idler gear cage as follows:

A. Tighten the two cage bolts alternately in small, uniform increments until bolt torque is 20 N·m (15 lb-ft).

B. Rotate the gears three full turns (or oscillate an equivalent amount.

C. Repeat Steps A and B until bolt torque remains at 20 N·m (15 lb-ft) after rotation.

E. Find the average of the two readings taken in step D. and add 0.018 inch. This total is the required shim pack thickness to produce a nominal 0.002 inch end play. DO NOT RELY ON END-PLAY MEASUREMENTS FOR VALIDATION OF BEARING SETTINGS. SEE STEP 9, BELOW.

8. Size and install the idler gear shim pack, install the O-Ring on the cage, install the cage and all of the retaining bolts and washers, and torque the bolts to 135 ± 20 N·m (100 ± 15 lb-ft.).

9. Follow the steps below to validate the bearing settings:

A. With all of the top and idler gear cage bolts tightened to full torque, measure the torque required to rotate the gears with a torque wrench of low torque range (rotate long enough to obtain a stabilized value). (This measurement process will hereafter be referred to as measurement of "rolling torque".)

B. Loosen the cage bolts on both cages, and set them finger tight. Check the rolling torque again. This value, the "baseline value", should be the same as that in step A). If it is lower, it suggests that the bearings on one or both of the gears has been set with preload instead of end-play. Tighten the bolts on one cage at a time and check the rolling torque to find where the preload exists. Add a 0.002 inch shim at the cage with indicated preload, and check the rolling torque again. If the value is now the same as the baseline value, the correct shim pack thinckness has been established. If the rolling toque remains higher than the baseline value, continue to add shims in 0.050 mm (0.002 inch) increments until the rolling torque with the cage bolts tight is equal to the baseline value. If this process is followed exactly, you will know that the bearings are set with between 0 and 0.050 mm (0.002 inch) end-play.

C. For cages with indicated end-play, REMOVE a 0.002 inch shim and recheck rolling torque. If the rolling torque remains at the baseline value, repeat the process until there is a noticeable increase in rolling torque. When this condition has been reached, install the last 0.050mm (0.002 inch) shim removed, and verify that rolling torque again equals the baseline value. If this process is followed exactly, you will know that the bearings are set with between 0 and 0.050 mm (0.002 inch) end-play.

3T6176 Transfer Gear (top gear)

Illustration 1