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3. Lubricating the blower fan shaft bearings
NOTE: Middleby recommends lubricating the blower
fan shaft bearings every three months.
Use a grease gun to lubricate the main blower fan shaft
bearings. See Figure 28. When lubricating the bear-
ings:
Use a high-quality NLGI #2, lithium soap grease with
petroleum oil, such as Middleby P/N 17110-0015.
Add the grease slowly until a small bead of grease
is present at the seals. AVOID OVERGREASING.
Excessive greasing may cause harm to the bearing.
Manually turn the blower shaft by pulling on the belt to
purge the grease. Wipe off any excess grease. The
oven cannot be operated until the rear shroud is replaced.
4. Blower belt tension
NOTE: Middleby recommends checking the blower
belt condition and tension every three months.
Check the blower belt for at least 1" (25mm) deflection
at the center, and for cracking or excessive wear.
Overtightening the belt will cause premature bearing
failure and possible vibrations. See Figure 29.
If necessary, adjust the tension of the belt by loosening
the two motor mounting bolts as shown in Figure 30.
Reposition the motor as neccessary until the correct
deflection is reached, then tighten the bolts.
IMPORTANT: Middleby uses two different types
of grease in blower shaft bearings:
DuPont Krytox® grease is used in some
PS536 ovens. Refer to Service Bulletin MM-
192 (included in the Appendices section of
this chapter) for details on identifying
Krytox® bearings.
All other ovens use the standard Middleby
high-temperature grease, P/N 17110-0015.
Mixing grease types within the bearing will
cause the bearing to seize. For all PS200 ov-
ens, be sure to use ONLY the standard
Middleby grease.
Figure 28
Bearing lubrication
Grease fittings
(1 per bearing,
2 total)
Figure 30
Repositioning the blower motor
Loosen bolts to
reposition motor
and adjust belt
tension
Figure 29
Blower belt tension
1 (25mm)
vertical
deflection
2. Blower balancing and direction of rotation
Proper blower rotation is extremely important. From
the rear of the oven, the blower shaft pulley should turn
in a clockwise direction. See Figures 25 and 26.
All blower fans are balanced at the factory. Any fan
found to be out of balance should be replaced. Vibra-
tion from an out-of-balance fan can cause poor baking
and premature bearing failure. Note that vibrations can
also be caused by other sources, including defective
motor or blower shaft bearings, loose bearings or mo-
tor mounting bolts, or an incorrectly tensioned fan belt.
SECTION 3 - SERVICING COMPONENTS