6.
Drive Belts
a. General
The engine cooling fan, alternator, fuel pump, and water pump are driven by a timing belt which
must be replaced if it becomes worn or damaged.
b. Preparation for Belt Check and Adjustment
All driven assemblies must be securely mounted in operating position before checking belt tension.
c. Checking Belt Tension (fig. 9)
Check belt tension every 1000 hours, or once a year, whichever comes first. A belt which is too tight
is destructive to bearings of the driven part. A loose belt will slip and cause inefficient operation of
the part being driven as well as wear to the belt.
Belt tension may be checked either with a gage or manually. Use Cummins Belt Tension Gage no.
ST-1293, or equivalent. Gage should indicate 90 to 110 pounds. If a gage is not available, tension
may be checked manually by depressing the belt with the index finger to determine the amount of
belt deflection obtained when force of approximately at a point halfway between pulleys on the
longest span of the belt.
d. Check Fan Belt (fig. 10)
(1)
Check belt tension (see above).
(2)
Remove the drive belt by lifting on the belt tensioner with a 1/2 square drive. The belt can then
be slid off the water pump pulley and worked off the other pulleys and around the fan.
(3)
Inspect the belt for damage.
a.
Traverse (across the belt width) cracks are acceptable.
b.
Longitudinal (direction of belt length) cracks that intersect with transverse cracks are
unacceptable.
(4)
Replace the belt if it has unacceptable cracks, is frayed or has pieces of material missing.
(5)
Check the belt tensioner while the belt is removed. It should spin freely without any wobble or
excessive (0.006") end play.
(6)
Install the drive belt.
7.
Generator Maintenance
The 400 Hz generator required no maintenance or service other than periodic cleaning. The unit is
brushless, and bearing(s) are permanently lubricated and sealed.
a. Cleaning
The generator may be cleaned by careful use of compressed air and/or a good, SAFE commercial
cleaner. Steam cleaning of the generator is not recommended because the use of steam and harsh
chemical compounds may result in damage to insulation and other generator components.
Do not use a flammable solvent. Be sure the unit is completely dry before
operating.
b. Adjustment
The generator itself requires no adjustment. Adjustment procedures for generator controls are
covered in 2-3.
CAUTION
OM-2084 / Operation and Maintenance Manual
90CU24 / Series 500392 Generator Sets
November 27/1997
Chapter 2-2
Page 11
