Acer 471558 manual Belt/Bearing Maintenance GB Unit, Recommended Relubrication Frequency in Months

Belt/Bearing Maintenance GB Unit

1.Belts tend to stretch after a period of time.

They should be checked periodically for wear and tightness. When replacing belts, use the same type as supplied with the unit.

2.Matched belts should always be used on units with multi-groove pulleys.

3.For belt replacement, loosen the tensioning device enough to allow removal of the belt by hand.

4.Once installed, adjust belts as shown in “Pre‑Starting Checks.”

5.Shaft bearings can be classified in two groups: relubricating and non-relubricating. All non‑relubricating bearings on model GB fans are factory lubricated and require no further lubrication under normal use (between -20º to 180ºF (-29º to 82ºC) in a relatively clean environment).

6.On GB belt driven fans, the standard cast pillow block bearings are factory lubricated and are provided with external grease fittings. Annual lubrication is recommended, or more frequently if needed (See Table 2). Do not over-grease. Use only one or two shots of lubricant with a hand gun. Maximum hand gun rating is 40 psi. Rotate bearings during lubrication where good safety practice permits. Caution should be employed to prevent over packing or contamination.

7.Grease fittings should be wiped clean. The unit should be in operation while lubricating. Extreme care should be used around moving parts.

8.Grease should be pumped in very slowly until a slight bead forms around the seal. A high grade lithium base grease should be used. (See Table 3)

9.To ensure tightness, check pulley setscrews. Proper keys must be in keyways.

10.Fan RPM should not be readjusted. Only use pulleys of identical size and type when replacing pulleys.

11.During the first few months of operation, check bearing setscrews periodically to ensure tightness.

12.If unit is to be left idle for an extended period, remove belts and store in a cool, dry place to avoid premature belt failure.

Recommended Relubrication

Frequency in Months

NOTE: If unusual environment conditions exist (extreme temperature, moisture or contaminants) more frequent lubrication is required.

A good quality lithium base grease, conforming to NLGI Grade 2 consistency, such as those listed here may be used.

Table 2: Suggested Fan Bearing Greasing Intervals

Interval	Type of Service
(months)
1 to 3	Heavy duty in dirty, dusty locations; high ambient
	temperatures; moisture laden atmosphere; vibration.
3 to 6	12 to 24 hours per day, heavy duty, or if moisture is
	present
6 to 12	8 to 16 hours per day in clean, relatively dry
	atmosphere
12 to 18	Infrequent operation or light duty in clean
	atmosphere
	Table 3: Grease Manufacturers

Manufacturer	Grease (NLGI #2)
U.S. Electric Motors	Grease No. 83343
Chevron U.S.A. Inc	Chevron SRI Grease #2
Mobil Oil Corporation	Mobilith
	Mobil 532
Texaco, Inc.	Premium BRB #2
	Texaco Multifak #2
Amoco Oil Co.	Rykon Premium #2
Exxon	Unirex N2
Shell	B Shell Alvania #2

Fan Inlet Connections

In order to assure proper fan performance, caution must be exercised in fan placement and connection to the ventilation system. Obstructions, transitions, poorly designed elbows, improperly selected dampers, etc. can cause reduced performance, excessive noise and increased mechanical stress. For performance to be as published, the system must provide uniform and stable airflow into the fan.

Good

Poor Poor Good

Dampers must open fully. Use motorized dampers in low airflow applications to reduce losses.

Avoid sharp turns or entrance conditions which cause uneven flow. Use turning vanes in elbows to reduce adverse effects.

Provide uniform airflow at fan inlet to assure optimum performance.

Provide uniform airflow at fan inlet and through the damper to assure optimum performance. The curb cap should be three wheel diameters from the radius. Use turning vanes in duct when possible.

8 Model G/GB Centrifugal Roof Exhaust Fans

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