Page 165 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Positive Displacement and Dynamic Blowers 147

housing. Apply a thin, even coat of silicone grease to the end of
housing before assembly.
12. Install free end plate.
13. Secure nondrive end plate (5) to rotor housing (3) with hex screws
(26). Be sure dowel pins are in housing.
14. Install spacer (57) and bearing (10) on each rotor shaft.
15. Place oil slinger (21) on lower bearing, install drive pin (68) and
secure with flathead socket cap screw (69). Use rotor shaft washer
(25) and flathead socket cap screw (29), to secure upper bearing
(1) on rotor.
16. Check clearance between face of the nondrive end plate and the
rotor lobe ends (.012 in. to .018 in.).
17. Check rotor tip to housing clearance.
Inlet side: .0125 in. to .014 in.
Discharge side: .0085 in. to .010 in.
18. Check interlobe clearance (See Figure 4-2C).
13. Adjust timing:
The driven gear is made of two pieces. The outer gear shell is fas-
tened to the inner hub with four cap screws (60) and is located with
two dowel pins (58). A .030 in. thick shim (16), made up of .003
in. laminations, separates the hub and the shell. By removing or
adding shim laminations, the gear shell is moved axially relative to
the inner hub which is mounted on the rotor shaft. Being a helical
gear, it rotates as it is moved in or out and the driven rotor turns
with it, thus changing the clearance between rotor lobes (Figure
4-2D). Changing the shim thickness .003 in. will change the rotor
lobe clearance .0015 in. When reassembling shell on hub, be sure
that timing marks coincide as shown in Figure 4-2B.
20. Bolt nondrive end cover (7) to nondrive end plate (5). Be sure gas-
ket (28) is placed between the cover and the end plate.
2 1. Mount bearing (50) and snap ring (47) on drive shaft (45) and fas-
ten to drive gear (8), using four hex screws (66) and Bock plate
(65). Drive shaft shall not run out more than .001 in. TIR.
22. Assemble cover (6) to blower. Install lip seal (13) on cover.

Some useful information should be tabulated In the vendor’s instruction
manual:
1. Torque values for:

Gear and bearing locknut
0 Rotor and drive shaft flathead screw
Gear end ball bearing retainer screw