Usage:
768C, 772B, 776 Tractors;
769C, 773B, 777 Trucks
Description of Change: New outer Duo-Cone seal groups are used in the service and parking brake groups on the above models. The new seals are cast from a nickel-chrome alloy which has better resistance to scuffing and scoring. Scuffing and scoring of the former seals which were made of stellite resulted in leakage of brake cooling oil past the seals. Identification of the new Duo-Cone seals can be made by the part number (3T6603 or 3T6605) which is cast onto the ring.
Adaptable As: The new Duo-Cone seal groups are a direct replacement for the former seal groups as shown in the chart which follows:
The list which follows are recommendations that must be followed to prevent damage to Duo-Cone seals before and during installation.
1. Keep the Duo-Cone seal groups clean and dry during shipment to a repair location.
2. Make sure the rubber toric ring is not twisted when installed on the seal ring.
3. Use a torque wrench to tighten and check the torque value of the brake assembly bolts. These bolts do not have to be removed for installation of the new seal groups, but must be checked. These bolts must be correctly tightened. If the bolts are not tightened correctly, the bolts can loosen and result in oil leakage and damage to the O-ring seals.
4. To prevent damage to the Duo-Cone seals during installation, use the correct seal installation tools. See the chart which follows:
5. Do not get oil on the rubber toric ring during installation in the retainers or in the brake housing.
6. Before the metal seal rings come together, use a dry tissue that is lint free to clean the faces of the seals; then use a clean tissue which has clean oil on it to put lubricant on the seal faces.
7. See the appropriate Service Manual for the correct wheel bearing adjustment procedure.
To adjust the wheel bearing, tighten the specified three bolts to a torque of 70 ± 7 N·m (50 ± 5 lb ft) while the wheel is turned.
| NOTICE |
|---|
Do not overspeed the rear wheels. This can score the seal faces.
|
8. With the machine still blocked up, and the rear wheels off the ground, operate the engine at 1000 rpm with the transmission in first gear. Let the wheels turn for 15 minutes (5 minutes in first gear "forward", 5 minutes in first gear "reverse", 5 minutes in first gear "forward").
 |
To prevent injury, make sure the wheels are completely stopped before checking the wheels for oil leakage.
|
 |
9. Inspect the wheels for oil leakage.