VALVE-BALL 8T6639 - Caterpillar

SR4 Generators Used With 3412 EnginesWhen operating in very dusty environments, such as near a rock crusher, fine dust can accumulate in the cavity between the flex plates (coupling) and the generator fan. See Illustration 1. When the engine is shut down, the dust can fall from the top of this cavity and settle on the bottom, creating an imbalance when the generator set is restarted. Excessive generator set vibration can be the result.
Illustration 1. Location of cavity where dust can collectTo determine if dust is causing a vibration problem, first, measure the vibration. Next, remove the dust from the cavity with compressed air and then measure the vibration again. If the vibration level is acceptable after the dust is removed, dust build-up probably caused the problem.
The best solution to a dust build-up problem is to move the generator set away from the source of the dust. Dust can shorten the service life of the generator and other electrical equipment. See the pamphlet "Operating Environment And Its Effect On SR4 Generators," Form SEBD0660. Air filter maintenance can also become a major effort and expense when operating in very dusty environments.
If a dusty operating environment can not be avoided, the modification that follows can be made to prevent dust build-up in the cavity between the flex plates and generator fan. This modification applies to 1500 or 1800 rpm 3412 Generator Sets only.
Generator Modification
The cavity between the flex plates and the generator fan can be sealed with two fabricated sheet metal plates and an O-ring seal. See Illustration 2.
Illustration 2. Location of fabricated sheet metal plates and O-ring seal.Use the procedure that follows to modify the generator.
1. Separate the generator from the engine and remove the flex plates (coupling). See the appropriate Service Manual, Disassembly and Assembly section.2. Clean the dust off the fan.3. Drill and tap six equally spaced holes for 1/4" x 20 threads in the fan as shown in Illustration 3.
Illustration 3. Dimensions for new plate mounting holes in fan.4. Fabricate 2 plates from 12 gauge [2.5 mm (.01") thick] mild steel sheet as shown in Illustrations 4 and 5.
Illustration 4. Dimensions for fabricated fan mounted plate.5. Split the hub mounted plate (Illustration 5) through one bolt hole. Put the hub mounted plate in position as shown in Illustration 2. The split in the installed plate should be in the same location as the balance weight. Use eight 5/16" x 18 bolts, 19 mm (.75") long, and eight 5/16" lockwashers to install the plate. Put 9S3263 Thread Lock on the bolt threads before installation.
Illustration 5. Dimensions for fabricated hub mounted plate. Reinstall any weights on the hub in the original location.6. Put 3S6252 RTV Silicone Adhesive Sealant on the hub in the area where the O-ring seal is to be installed. Install the O-ring seal [880 mm (34.6") circumference x 10 mm (.4") thick] on the hub. The O-ring seal can be made from 880 mm (34.6") of 10 mm (.4") thick bulk stock and joined with