37-1-615 Page 40
EXAMPLE FOR 9CDL18 BLOWER: Micrometer reading of .015
” plus .009” discharge end clearance,
FIGURE 7-8, plus .002
” crush gives shaft shim set thickness of .026”. Figure shaft shim set for each
rotor and record measurements which will be used later in the assembly under Steps 15 and 16.
FIGURE 7-7
The second set of measurements is used to determine total end clearance
. To give proper rotor end
clearance at both suction and discharge ends (referred to as total end clearance) the distance between the
face of the bearing carriers must be equal to the rotor length plus both end clearances. Total end clearance is
obtained by adding shims (21) as required between the flange of the housing (1) and the discharge end bearing
carrier (5). The thickness of the shim set is determined as outlined in Steps 9 & 10.
Models
Total End Clearance
(Suction & Discharge)
Suction
End
Discharge
End
9CDL13
.025
.016
.009
9CDL18
.032
.023
.009
9CDL23
.038
.029
.009
Dimensions are for Ideal Clearances. Allow +/- 0.001 for Tolerance
FIGURE 7-8 – ROTOR END CLEARNACE CHART (UNIT COLD)
9. With a depth micrometer (FIGURE 7-9) measure the distance from the end of the rotor lobes (2, 3) to
the end of the housing (1). Rotate rotors to check each lobe and record the
largest micrometer
reading
. If the measurement varies more than .005
”, remove the rotors and check for burrs on the
gear end carrier face and the end of the rotors. To the largest micrometer reading add the Total End
Clearance shown in the clearance chart, FIGURE 7-8, plus .002
” for crush fit, to determine the
thickness of the shim set.
EXAMPLE FOR 9CDL18 BLOWER: Micrometer reading of .005
” plus .032” total end clearance plus
.002
” for crush gives a shim set thickness of .039”.
10. Select the correct thickness of aluminum shims to give the shim set established in Step 9. Check the
thickness of the shims with an outside micrometer (FIGURE 7-10). Place the shims on the end of the
housing (1), matching the pointed section of the shims with the contour of the housing. Remove
bearing spacers from the discharge end bearing carrier, FIGURE 7-7. If measurements in Step 8
differ, make sure the bearing spacer is placed over its respective shaft extension to assure proper end
clearance of each rotor. Apply Loctite 620 to the shaft extension of the rotor in the area where the
spacer will be located. Slide spacers over the shaft extensions, grooved end toward the rotor. Be sure
the spacer fits solidly against the rotor.
FIGURE 7-9
FIGURE 7-10