mycom 200VLD User Manual

2205Q2JE-HO-S6-N_2020.01.
Chapter 5 Maintenance and Inspection
SCV-series Screw Compressor 5.4 Disassembly and Inspection
5-30
5.4.9 Rotors and Main Rotor Casing
5.4.9.1 Disassembly
a) The rotor can be easily pulled out. While you can pull out the rotor either from the M or F side, you
should be very careful in the work as either rotor is very heavy.
When pulling out the M rotor (or F rotor) first, pull out about 2/3 of the full length of the rotor by
holding the shaft upward and turning it in the CW (or CCW) direction.
 You should carefully note that the rotor must be rotated in the specified direction
while pulling it out. If the M (F) rotor is not turned during the pulling out process,
the F (M) rotor can also be pulled out together.
b) As a preparation, use a nylon belt or other lifting belt that will not blemish the lifting surface to
support the center of the rotor. Then, pull out the rotor while slightly lifting up the rotor using the belt.
c) The pulled out rotor should not be directly placed on the floor. Use appropriate wood boards to
support the rotor as a cushion to prevent blemishing or use V-blocks to support the shaft to prevent
blemishing of the outer surface.
5.4.9.2 Inspection
a) No abnormality should be observed on the surface of the rotor lobes under normal operations.
Regarding the contact surface of the lobes, black luster should be seen on the root area of the M
rotor lobes and on the tip area of the F rotor lobes.
In other cases, when the suction gas or oil is contaminated by fine dust, there may be fine linear
scratches on the shaft surface, in the direction perpendicular to the shaft axis. If any such flaw is
found, use a fine sandpaper or grindstone to smooth the surface.
b) In case of ammonia refrigerant or gas compressor, the non-contact surface of the rotor may be
discolored by rust or deposits. Use sandpapers or others to finish the surface according to the
degree of the problem.
c) Then, check the bearing areas of the rotor shaft. Two types of finishing are used: one is the
induction hardening (polish finishing) for the standard specification, and the other is the hard
chrome plating (polish finishing), as a special specification. The most suitable finish is selected
according to the type of refrigerant and operation conditions.
Very little wear will be present unless the compressor is operated for a long time using dirty oil or
any hard matter is buried in the metal of the inner circumference of the bearing.
d) Check the portion of the shaft on which the thrust bearing is mounted for any trace to show that the
inner
race of the bearing has rotated.
If the lock nut that fastens the inner race of the thrust bearing is loosened, or if the bearing is
abnormally worn, the inner race will become loose and rotate. If any trace of rotation is seen, correct
the problem as appropriate.
e) Check the portion of the shaft on which the mechanical seal is mounted for any scratches and/or
trace to show that the oil seal lip has hit strongly. Particularly, damage in axial direction may cause
the oil and/or gas leakage from the shaft seal part, if it is not disappeared in hand finishing, repairing
the rotor is required.
In this case, contact our sales offices or service centers.
f) Check the inner surface of the rotor casing.
There is a narrow clearance between the periphery of the rotor and the rotor casing. Any slight flaw
present on the tip of the rotor lobes or on the inner surface of the rotor casing, due to small foreign
matters, will not be a problem.
If there is any trace to show that the tips of the rotor lobes have hit the inner surface of the rotor
casing, it is an abnormal condition. In such a case, the possible cause is that the bearing is worn out.
Take proper actions by finding the cause of the problem, such as contamination of the lubricating oil
or entrance of foreign matters.

mycom 200VLD Specifications

General

Brand	mycom
Model	200VLD
Category	Air Compressor
Language	English