Middleby Marshall PS360, PS570, PS200 PS500-series blower wheel orientation, Bearing lubrication

SECTION 3 - SERVICING COMPONENTS

2.Blower balancing and direction of rotation

Proper blower rotation is extremely important. Proper blower rotation is shown in Figure 45.

Early PS570 blower wheels were positioned so that the open end of the wheel faced into the baking cham- ber. This was changed on the PS570S (and all later models) to improve airflow. Note that this also means that on early PS570 ovens the counterclockwise wheel is moved to the left side of the oven, and the clockwise wheel moved to the right side, so that the wheel blades point in the same direction. This is reflected in the Part Number Reference information on Page 77.

All blower wheels are balanced at the factory. Any blower wheel found to be out of balance should be re- placed. Vibration from an out-of-balance wheel 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 motor mounting bolts, or an incorrectly tensioned fan belt.

3.Lubricating the blower shaft bearings

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 PS555/570- series ovens, be sure to use ONLY the stan- dard Middleby grease.

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 46. 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.

Figure 45

PS500-series blower wheel orientation

Clockwise:	PS570:	Counter-
Right end	Open end of wheel faces IN	clockwise:
		Left end

Counter-	PS570S, PS570G, PS555:	Clockwise:
clockwise:	Open end of wheel faces OUT	Left end
Right end

Note slant of blades

Figure 46

Bearing lubrication

Grease fittings (1 per bearing, 4 total)

PS570,

PS570S

Grease fittings (1 per bearing, 4 total)

PS570G,

PS555

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