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Installation, operation and maintenance instruction
High voltage flameproof motors for explosive atmosphere
AMD Rg 355-400-450-500
Sleeve bearings maintenance
Supplier
EXXON
SHELL
MOBIL
BP
TEXACO
FINA
REMARK: The required value of ISO VG viscosity
for the oil is clearly indicated on the outline drawing
of the motor and on the lubrication plates.
Parts subjected to wear
When the machine starts up and runs down, it passes
through the mixed friction zone, i.e. the shaft speed is too
low, and hence also the pressure produced in the
lubricating gap, to allow the shaft to rotate solely on an oil
film.
This means that metal-to-metal friction is present which is
unavoidably connected with wear. The speed at which
mixed friction changes to fluid friction and vice versa is
called the transition speed. The transition speed can be
kept sufficiently low by suitable design.
For machines destined to have a large number of run-
downs and have a high transition speed it is
recommendable to shorten the run-out time by braking.
Where longer periods or operation at, or in the vicinity of
the transition speed are expected, (e.g. slow rotation of
variable speed drives) an oil-pressure jacking system
must be employed by design.
The visual analysis of the bearing contact surfaces
illustrate whether the bearings are correctly fitted and
whether they are suited to withstand the axial and radial
forces arising during operation, and also offer the best
information for judging whether the oil supply to the
bearings is sufficient for their proper lubrication and
cooling.
The bearing seals are to be dimension checked and
replaced, should oil leakage be discovered during the
periodical inspections.
The oil rings on horizontal machines are also to be
checked with respect to dimensions and exactness of
form if during the periodical inspections it is noticed that
they are not running properly.
ISO VG 68
315 SSU/100°F
Teresso 68
Tellus Oil S68
DTE26
Energol CS68
Rando Oil 68
CIRKAN 68
*) Mean value of any two measurements displaced 90° from
each other.
A general statement covering replacement intervals for
bearing components cannot be made. However, the
planned inspections permit timely recognition when
bearing parts are worn and need replacing.
Bearing's wear measurement
The operations to be carried out for the bearing's wear
measurement are the following:
-
-
-
-
-
-
The measurements shall be taken at least on 3 points
along the axial dimension of the journal and for every
point
measurements in total).
The clearance between the journal and the bearing is
calculated by the difference between the average of the
two measurements (journal and inner bore).
Sheet No.
3AAM101043 E
Rev. C
Page 2 of 4
Oil ring
Permitted diametrical
Inner diam. d1
Out-of-roundness *)
140-200
200-280
280-400
400-500
500-600
600-760
For Ex db motors it is compulsory to verify every two
years, or 10000 running hours, the wear of the
bearings, and replace the bearings when their
dimension are out of the tolerance field. This
precaution is necessary to avoid contacts between the
static and rotating components of the flame inner
seals due to change of their gap caused by the wear
of the bearings. Remember that the design gap is in
the order of tenth of millimetres.
Open the bearings' housing according to the
instruction given in the "Dismantling and assembly
instruction" section of this manual, "Sleeve bearing"
paragraph.
Raise the shaft in accordance with the instructions.
Split the two half of the bearing's shell.
Remove both bearing's shell and reassemble them
separately.
Using centesimal micrometers, measure the inner
shell bore diameter and the shaft journal diameter.
Reassemble or replace the shell in accordance to the
instructions.
on two radial direction
Clearance = inner bore diam – journal diam.
i.e. : Clearance = 90.12 - 89.88 = 0.24 mm
01.2023
0.5 mm
0.6 mm
0.7 mm
0.8 mm
0.9 mm
1.0 mm
90°
displaced (6
Issued by: MOLM
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