Installation, operation and maintenance instruction
High voltage flameproof motors for explosive atmosphere
AMD Rg 355-400-450-500
Sleeve bearings maintenance
Issued by: MOLM
Sheet No.
3AAM101043 E
Rev. C
Page 1 of 4
01.2023
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Sleeve bearings
Ex db motors are always designed with endshield
bearings. The kind of bearing and details thereof are
described in the specific technical documentation of the
Order. The bearings with self-lubrication are supplied
with oil from the oil sump by one or more oil rings. The
oil rings can be either single piece or split design. One
opening is provided in the bearing housings through
which the oil rings can be checked for correct functioning
(e.g. uniform and smooth running, oil transport). Lateral
openings are even provided, fitted with sight windows.
General points concerning sleeve bearings
The bearing housings of horizontal machines and those
of vertical machines are all fitted with at least one oil
sight window. When the bearing is fitted inside a
ventilation hub the sight window is placed outside the
hub. The maintenance instruction plate fastened to the
machine shows data such as initial oil fill quantity per
bearing, rate of oil flow per bearing, oil type and oil
change interval.
The lube oil may only be topped up or changed when
the
machine is stationary.
When filling with oil observe the level at the bearing oil
sight window on the bearing housing. The correct level
is indicated by a mark in the middle of the sight window.
The level must not fall below the lower rim of the sight
window. These oil level details are referred to the
stationary machine and to an oil temperature equal to
the ambient temperature. During operation, the oil level
in the bearings will rise somewhat. This is absolutely
normal and does not represent a danger of oil
overflowing into the machine. After shutting the machine
down and awaiting the oil to be cooled, check that the
level falls to the mark on the sight window; if not, refill.
Whenever the bearing shells or the bearing segments
are changed, run the machine for approximately 3 hours
with the new parts and then drain the oil from the bearing
housings. Flush out bearings with non-halogens
industrial solvents (SANGAJOL, VARSOL, or WHITE
SPIRIT) and refill with new oil. This measure ensures
that any metal particles rubbed off during running-in are
removed from the bearing housings.
In the case of sleeve bearings, a bearing inspection after
running on load for some hours during commissioning or
changing the shells is the best precaution to avoid
possible damages and improve the motor availability.
Bearing insulation
The arrangement of the bearing insulation (if any), is
shown on the separate sheet “Bearing insulation” and on
the technical documentation of the Order. These
documents also indicates whether one or both bearings
are insulated, and whether the insulation on one bearing
is bridged over for measuring purposes.
Oil change
Oil changing is largely dependent upon the operating
time, the number of switching operations, the operating
temperatures and the amount of oil contamination.
If not otherwise specified on the rating plate, cleaning
periods are advisable during operations with an oil
change after approximately 8000 operating hours in case
of self-lubricating bearings and approximately 20000
operating hours in case of circulating oil lubricated
bearings.
Shorter intervals are required in case of frequent starting
and stopping, high oil temperatures or excessive
contamination through external influences, for example.
An oil change can also be required by strong turbidity or
by a sudden increase in temperature without any external
influence.
A chemical analysis offers reliable information on the
lubricity (ageing) of the oil. The first examination is to be
made during commissioning, with further examinations
after 6 or 18 months. On the basis of these examinations
the extension the oil change interval can be decided,
mainly when large quantity of oil is involved.
Types of oil
The oil used in the bearings must have a viscosity value
as defined in ISO 3448. As a general rule, the following
mineral oils are used in the motors.
Rotational speed of the
shaft journals (rpm)
Oil types
> 1800
ISO VG 32
150 SSU/100°F
between 1200 and 1800
ISO VG 46
214 SSU/100°F
1200
ISO VG 68
315 SSU/100°F
REMARK: For use of synthetic oils, ask information from
the machine manufacturer!
Here are indicated some type of oil easily obtained on the
market and suitable for the use on electric motors
2 and 4 poles motors
Supplier
ISO VG 32
150 SSU/100°F
ISO VG 46
214 SSU/100°F
EXXON
Teresso 32
Teresso 46
SHELL
Tellus Oil S32
Tellus Oil S46
MOBIL
DTE24
DTE25
BP
Energol CS32
Energol CS46
TEXACO
Rando Oil 32
Rando Oil 46
FINA
CIRKAN 32
CIRKAN 46
6 and more poles motors
