Reinstallation Of The Swing Bearing Seal Of Certain Wheeled Excavators Caterpillar

Problem:

The lower 7Y-0423 Seal of the swing bearing may be improperly glued in the seal groove. The seal may be forced out of the groove, thus allowing grease to leak out of the swing bearing.

Table 1 identifies the machines that may be affected by an improperly installed lower seal of the swing bearing.

Solution:

When the replacement of the lower seal of the swing bearing is necessary, use the following required parts, tools, and procedure for the proper installation of the new seal.

Table 2 identitfies the parts that are required for the proper installation of the new seal.

Table 3 identifices the tools required for the proper installation of the new seal.

Rework procedure:

1. Be sure the machine has spent several hours in a warm environment (>15 degrees C)/(>59 degrees F) to improve the curing process of the adhesive.

Illustration 1. Step Assembly

Illustration 2. Step Assembly

NOTE: Support the step assemblies during removal from the machine. Fasten a suitable lifting device or a hoist to the step assembly . Position the lifting device until the step assembly is balanced. The weight of the step assembly is approximately 65 kg (145 lb).

2. Remove the bolts (2) that secure the step assembly (1) to the machine, as shown in Illustration 1. Remove the step assembly from the machine.

3. Remove the bolts (3) that secure the other step assembly (4) to the machine, as shown in Illustration 2. Remove the step assembly from the machine.

4. Clean the upper surface of the lower frame with brake cleaner in order to have a clean working area.

5. Position the machine in an area where the upperframe can rotate freely through 360 degrees. Illustration 3.

6. Remove the four bolts (5) that fasten the swing bearing to the upper frame at the left hand side of the machine, as shown in Illustration 3. This will allow easier access to the swing bearing seal groove.

Illustration 3.

Illustration 4.

Illustration 5.

Illustration 6.

7. Use the following cleaning procedure in the area where the four bolts have been removed (6), as shown in Illustration 6:

a. Pre-clean the seal groove area with clean rags.

b. Use Tool (C) in order to remove the grease from the groove, as shown in Illustration 6.

c. Use Tool (A) and rags in order to remove any remaining adhesive from the groove.

d. Spray the groove with Locite 7063 Cleaner.

e. Use Tool (A) and rags in order to clean the seal groove.

f. Thoroughly clean the groove with Tool (A) and clean rags, until the groove is totally free of grease in this area.

g. Swing the upper frame 90 degrees and repeat the above procedure until the whole circumference of the groove has been thoroughly cleaned. 8. Carefully wipe the new 7Y-0423 seal with acetone. Allow the seal to dry.

8. Carefully wipe the new 7Y-0423 seal with acetone. Allow the seal to dry.

9. Apply Loctite Adhesive 454 over 30 cm (11.75 in) of both the lower and the upper internal surfaces of the bearing seal groove.

NOTE: You must make sure that the seal bottoms in the seal groove (full depth).

NOTE: Do not apply the loctite adhesive over more than 30 cm (11.75 in) at a time, otherwise the adhesive may dry before you install the seal into the groove.

10. Repeat Step 9 on the next 30 cm (11.75 in). Slowly swing the upper frame as needed, until the seal is installed in the whole circumference of the seal groove.

11. Carefully cut the seal to the proper length. Use the same Loctite 454 in order to glue both seal ends together. Apply the adhesive to the ends of the seal. Carefully install this portion of the seal into the groove and firmly hold the seal ends together for at least one minute.

Illustration 7.

12. Install the four bolts (5) that secure the swing bearing to the upper frame, as shown in Illustration 7. Tighten the bolts to the proper torque as listed in Table 4.

13. Reinstall the steps on both sides of the machine. Note: The curing process of the adhesive is complete after 24 hours.

14. Make sure that the machine operator applies grease to the two swing bearing grease fittings. These grease fittings are located at the head end of the right boom cylinder. Apply grease to the fittings until the grease overflows the lower bearing seal.

COPYRIGHT 2000 CATERPILLAR ALL RIGHTS RESERVED