REASSEMBLY (Cont) - TM-3-4240-284-30-P0164

TM 3-4240-284-30&P

2-11. MAIN FAN - MAINTENANCE INSTRUCTIONS (Cont).

ITEM

ACTION

LOCATION

REASSEMBLY (Cont)

5. Check the contour fit between the fan impeller and

Main fan

the impeller cover.

IMPELLER COVER

6. Position the fan housing (4) vertically with input end

up.

7. Install bushing (12) on rotor shaft.

8. Install the fan impeller (8) on the rotor shaft without

the woodruff key. Do not install self locking nut.

9. Install the impeller cover (3) on the fan housing and

secure with two screws (1) and two washers (2) 180

degrees apart.

NOTE

The fan impeller must be firmly seated

against the bushing on the rotor shaft in

order to obtain an accurate reading for

dimension "A".

10. With the fan impeller against bushing, use a 2 inch

depth micrometer with two parallel bars (1/2 inch by

1 inch by 8 inches). Measure the distance from the

top of the parallel bars to the machined surface on

the fan impeller as shown. Record as dimension

"A".

NOTE

The fan impeller must be firmly seated

against the impeller cover to obtain an accu-

rate reading for dimension "B".

Pull up on the fan impeller to seat against the

impeller cover and take a second measurement

using the same technique as in step 10 and record

IMPELLER GAGE DIAMETER. (ADD SHIMS

as dimension "B".

BETWEEN IMPELLER AND SPACER TO

OBTAIN 0.007 TO 0.012 INCH AXIAL

CLEARANCE BETWEEN FAN IMPELLER

AND IMPELLER COVER.)

2-148