NUT 2990961 - Caterpillar

TECHNICAL INFORMATION BULLETIN April 30, 2003
Product Family All 3508B Single Bearing Generator Sets
Component Code: 4456SUBJECT: Check Bolt Torque on Flex Plates of Certain 3508B Single Bearing Generator Sets
PROBLEM:
Two 3508B single bearing generator sets were documented by dealers as having a loose 8T-9396 Bolt. The 8T-9396 Bolt, a component of the 153-0191 Installation Group, is used to attach the generator fan to the flex plate. During the next scheduled service interval, Caterpillar recommends that all twelve 8T-9396 Bolts that connect the generator fan to the flex plate be checked for proper torque. The dealer may have loosened these bolts during the required generator set alignment procedure that was conducted during installation.
SOLUTION: Use the following procedure to check bolt torque.
Illustration 1. Generator shield and generator screen.
Remove the generator shield and generator screen to gain access to the coupling bolts. Refer to Illustration 1.
Illustration 2. 8T-9396 Bolt.
To indicate initial bolt position, mark the bolt head and mating surface on each of the twelve coupling bolts (8T-9396).
Note: For each of the twelve coupling bolts, perform the next three steps (Step 3 through Step 5) one bolt at a time.
Loosen the bolt just enough to remove most of the clamp load.
Re-torque the bolt to the mark (made in Step 2). Record the torque value. This is the torque value under which the bolt was operating.
5. Torque the bolt to the standard torque of 215 +/- 40 Nm (158.6 +/- 29.5 lb ft). The bolt should rotate to approximately 5 degrees beyond the mark. This last step is required because of bolt stretch and mating surface compression that occurred during previous torquings.
After Steps 3 through 5 have been completed for all twelve bolts, reassemble the generator shield and generator screen. Tighten shield and screen bolts to their standard torque value.
7. If any 8T-9396 Bolt torque value is found to be less than 175 Nm (129.1 lb ft), call Griffin Power Systems Customer Service Group at 770-233-3911. Notify the Griffin Power Systems Customer Service Group of the package serial number.
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