2.
Coupling Screws (Routine Coupling Maintenance)
Failure to verify proper coupling screw installation may result in coupling failure
and damage to the equipment.
If the generator set is functioning properly, servicing the coupling assembly will be essentially limited to
checking the screws which attach the flexible coupling to the engine flywheel of the generator set.
These 8 screws should be checked periodically to make certain that: (1) screws of proper type, length,
and hardness are installed, (2) that the threads of the screws are not stripped, and (3) that they are
torqued properly. Proceed as follows to check coupling screws.
a. Remove the sheet metal covers from around the generator housing and the flywheel housing.
b. Refer to Figure 2. Hold a short iron bar through the flywheel housing against the fan blades of the
fan and coupling assembly to block the armature against clockwise rotation. Do this carefully to
avoid damaging the fan blades.
c. Use a long-handled, reversible ratchet drive fitted with a 5/16-inch Allen wrench to remove one
coupling screw. Examine the screw. Screws specified for this coupling are Hobart Part No.
402789-004, which are socket-head, 3/8 - 16 X 3/4 inch long.
NOTE: Use of the proper coupling screws for replacement is very important. Replacement screws
MUST be those specified above, torqued to 40 - 45 foot-pounds (54 - 61 Nm). There is NO
ACCEPTABLE SUBSTITUTE for these screws.
d. Check the threads of the screw for stripping and replace it if the threads are stripped. If the screw is
not stripped, reinstall it and torque it to 40 - 45 foot-pounds (54 - 61 Nm).
e. Repeat the steps b, c, and d above for the remaining seven screws.
f. Reinstall covers around housings.
Chapter 3-1
November 1, 2000
Page 2
Revised 03/01
OM-2094 / Operation and Maintenance Manual
Jet-Ex 5D / Series 500285/ Generator Set
Access to Coupling Screws
(for removal and
installation)
Figure 2
CAUTION
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