37-1-614 Page 43
Models
Total End Clearance
(Suction & Discharge
Suction
End
Discharge
End
7CDL11
.021 .014 .007
7CDL14
.025 .018 .007
7CDL17
.028 .021 .007
Dimensions are for Ideal Clearances. Allow +/- for Tolerance
FIGURE 7-8 – ROTOR END CLEARNACE CHART (UNIT COLD)
8. To the micrometer reading add discharge end clearance shown in clearance chart, FIGURE 7-8,
page 43, and .002” for crush fit of shims and parts. This sum gives the thickness of the shim set
(22, 23) for positioning the rotor the required distance from the face of the carrier for running
clearance at the discharge end.
EXAMPLE FOR 7CDL14 BLOWER: Micrometer reading of .015” plus .007” discharge end
clearance, FIGURE 7-8, page 43, plus .002” crush gives shim set thickness of .024”.
Figure shim set for each rotor and record measurements which will be used later in the assembly
under Step 15 and 16.
The second set of measurements is used to determine total end clearance
. To give proper rotor end
clearance at both inlet 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 and the
discharge and bearing carrier. The thickness of the shim set is determined as outlined in Steps 9 and 10.
9. With a depth micrometer (FIGURE 7- 9, page 43), measure the distance from the end of the rotor
lobes to the end of the housing. 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, page 43), plus,
.002” for crush fit, to determine the thickness of the shim set.
EXAMPLE FOR 7CDL14 BLOWER: Micrometer reading of .005” plus .0.025” total end clearance
plus .002” for crush gives a shim set thickness of .032”.
FIGURE 7- 9 – DEPTH MICROMETER
FIGURE 7-10 – OUTSIDE MICROMETER
