Centering Fan Wheel — If fan and fan shaft assembly are not properly centered, blades may scrape against the blower side scroll plate or may create an objectionable whistling noise. It may be necessary to adjust individual fan wheels or move en- tire fan shaft. See the following two sections.
Fan Shaft Position Adjustment — Loosen set- screw or locking collar of each fan shaft bearing. Slide shaft into correct position and replace locking collar (Fig. 21). To re- place locking collar, push collar up against inner face of bear- ing. Turn collar in direction of fan rotation until tight, and tight- en setscrew. Tightening locking collar in direction of fan rota- tion results in further tightening of collar should setscrew work itself loose.
Individual Fan Wheel Adjustment — Loosen the 2 locking bolts holding fan wheel hub to shaft. See Fig. 20. Position fan wheel in center of the fan housing and tighten locking bolts. Clearance between wheel and housing should be the same on both sides.
Fan Belts — Motor mounting plate and motor support angles are slotted to permit both vertical and horizontal adjustment. Adjust belt(s) for correct deflection by loosening motor plate mounting bolts, moving motor/plate assembly forward or back, and retightening bolts. Press down on belt with one finger midway between fan and motor pulleys to check deflection. The correct deflection is 1/8-in. (3.2 mm). See Fig. 22.
If complete belt replacement is required during servicing, loosen the motor plate mounting bolts (Fig. 22), move motor/ plate assembly towards fan pulley, and pull belt(s) off pulleys. Reverse the procedure with new bolts and readjust deflection.
Fan Rotation — Correct fan rotation with respect to fan outlet is shown in Fig. 23.
To reverse the direction of rotation of a
Fig. 21 — Fan Shaft Bearing
Fig. 22 — Fan Motor Mounting
22
