Emerson Vilter VSG128, Installation, Operation And Service Manual

Page: 41 / 84

5 – 7
Section 5 • Maintenance/Service
HPLD Single Screw Compressor • Installation, Operation and Service Manual • Emerson • 35391HP
Method of Inspection
A) Preparation
Shut down and de-pressurize the unit (please see
Preparation of Unit for Servicing on page 5-2 for proce-
dure details).
B) Main Rotor Bearing Inspection
1. Remove the coupling guard, then remove the cen-
ter member (optional) from the coupling.
2. To measure the radial bearing clearance, attach a
dial indicator to the compressor shaft as shown in
Figure 5-6 and zero the indicator. Place a lever arm
and fulcrum as shown in Figure 5-6 and apply force
at the other end of the lever (record the measure-
ment). See Table 5-2 for the maximum radial clear-
ance value.
Compressor Inspection
Vilter
TM
HPLD Single Screw Bare Shaft Compressors are
designed for long periods of trouble free operation with
a minimum of maintenance. However, a yearly inspec-
tion is recommended so any irregular wear is noted and
rectified. At this time, the bearing clearance is measured
for the main rotor and gaterotors, and gaterotor back-
lash and float should also be inspected.
The following procedures are used when measuring the
main rotor and gaterotor bearing clearance, gaterotor
backlash and float.
Bearing Inspection
NOTICE
If clearance measurements are out of tolerance,
contact Vilter Service Department for further
assistance.
CAUTION
When taking the measurements, do not exceed
100 lbs of force at point of contact or damage may
result to the bearings.
Determining Maximum Applied Force For Main
Rotor Bearings And Gaterotor Bearings
To determine maximum applied force, take the maxi-
mum applied force at hub/shaft multiplied by length of
A and divide by the length of B .
This is the maximum force that should be applied on the
lever.
(Applied Force x A)/B = Applied Force (Maximum)
So, using a 36” (or 91.4 cm) lever with pivot space of 6”
(or 15.2 cm) would make the maximum applied force to
be 20 lbf (or 89 N). Calculation is as follows:
(100 lbf x 6”)/30” = 20 lbf ( Max . Applied Force )
(445 N x 15.2 cm)/76.2 cm = 89 N ( Max. Applied Force )
B
A
Lever
Wooden Block
or Fulcrum
Applied
Force
Force at
Hub/Shaft
Pivot Point
As a quick reference, Table 5-2 shows the maximum ap-
plied forces for 36” lever with 6” pivot for all HPLD com-
pressor models.
Table 5-2. Maximum Main Rotor Bearing
Clearance
Side View
Rigidly attach dial indicator.
Direction of shaft
movement.
Applied Force
Shaft being pushed by use of lever.
Figure 5-6. Bearing Radial Clearance
Inspection
Models
VSS,
VSG,
VSH
Max.
Axial
Clearance
in. (mm)
Max.
Radial
Clearance
in. (mm)
Max.
Force
at Hub/
Shaft
lbf (N)
Max.
Applied
Force
(36” Lever, 6”
Pivot)
lbf (N)
128, 145,
160, 180,
204, 222,
243
0.002”
(0.051
mm)
0.006”
(0.152
mm)
100 lb
(445 N)
20 lb
(89 N)