LUBRICATION
One may take exceptions to this general recommendation on
sealed-for-life or maintenance-free gear units or smaller and less
costly gear units. In these instances, the replacement cost of the
gear unit is often small compared to the costs associated with this
type of oil analysis program.
Proper gearbox lubrication is essential in order to reduce friction,
heat, and component wear. Lubricants reduce heat and wear by
inserting a protective “fluid boundary” between mating parts and
preventing direct metal to metal contact. Lubricants also help
prevent corrosion and oxidation, minimize foam, improve heat
transfer, optimize reducer efficiency, absorb shock loads and
reduce noise.
NORD suggests replacing the gear oil if oil analysis indicates
any of the following:
• Viscosity has changed by approximately 10% or more.
All reducers are shipped from the factory with a pre-
determined oil fiIl level in accordance to the specified reducer
size and mounting position (See pages 5-7).
Actual oil volume can vary slightly depending upon the gear
case size, mounting and ratio. Prior to commissioning the
reducer, check the oil-fill level using the reducer’s oil-level
plug and drain or add additional oil as needed.
• Debris particles (silicon, dust, dirt or sand) exceed 25 ppm.
• Iron content exceeds 150-200 ppm.
• Water content is greater than 0.05% (500 ppm).
• Acid number tests indicate a significant level of oxidative
break-down of the oil and a critical reduction in
Performance.
OIL
PLUG OPTIONS
Standard Oil Type
All gear units are assembled with the oil fill-level, oil-drain and
vent plugs installed in their proper locations, according to the
specified mounting position that is shown on the reducer nametag
(See Pages 5-7). All standard plugs are metric and utilize sealing
gaskets between the head of the plug and the reducer housing.
The standard NORDBLOC.1 gear units are supplied with mineral-
base oil, ISO viscosity grade VG220.
Gear units may also be supplied with specific lubricants designed
to operate in certain environments, extend service life, or extend
the service temperature range.
Consult the lubrication decal
adjacent to the fill plug to determine the type of lubricant installed
at the factory.
Drain Plug
All reducer drain plugs are metric socket
head cap screws. For ease of draining the
spent oil from the gear reducer use the
socket head screw located at the lowest
part of the gearbox.
Fill Level Plug
For ease of identification, it is NORD’s
standard practice to provide a hex-head
screw for the fill-level plug
Oil Viscosity
Viscosity or the oil’s resistance to shear under load is often
considered the single most important property of any gear oil.
There are three primary reasons to consider a lubrication viscosity
change as follows:
1.
Low temperature
gear oils should be selected so that the
pour point is at least 9
°
F (5
°
C) lower than the expected
minimum ambient temperature. In extreme cases, consider
a lower ISO Viscosity rating and test the critical performance
of the gear box under cold start-up.
Vent Plug Options
Proper reducer venting allows for air pressure differences that
occur during operation, between the inner space of the reducer
and the atmosphere, while ensuring leak-free operation. The
Autovent™ is standard on all NORDBLOC.1 gear units.
2.
High temperature
applications may require an increase in
the lubricants viscosity to assure proper lubrication
conditions in the critical load zones of the gear unit. NORD
also recommends switching to synthetic oil if oil sump
temperatures exceed 176-185
°
F (80-85
°
C).
Autovent™
The AUTOVENT™ helps prevent bearing
and gear damage by blocking entry of
foreign material (water, dust, corrosives,
etc.) through a breather that acts like a
check valve. The typical design utilizes a
spring pressing a ball or a sealing plunger,
which presses against a machined orifice.
The check valve opens at approximately 2
psi during operation and closes tightly when
the gearbox cools, producing a slightly
negative pressure to ensure a tight seal.
This keeps contaminants out of the oil,
helps maintain proper oil cleanliness,
reduces contamination, oil foaming and
oxidation. The AUTOVENT™ is perfect for
humid conditions, washdown applications,
and dusty environments.
3.
In cases of extreme load conditions
, gear pairs and
antifriction bearings may be more susceptible to scuffing
wear. In these operating conditions, it may be beneficial to
consider an increased lubrication viscosity and/or lubrication
with improved antiwear additive packages.
NORD recommends that the user consult with their primary
lubrication supplier when considering changes in oil viscosity.
Maximum Oil Sump Temperature Limit
To prevent reducer overheating, the reducer’s maximum oil sump
temperature limit must not be exceeded for prolonged periods of
operation (up to 3 hours continuous operation depending upon
reducer size).
Open Vent
Maximum Oil Temperature Limit
Oil Type
NORD
AGMA 9005-D94
Mineral
80-85 °C (176-185 °F)
95 °C (203 °F)
Synthetic
105 °C (220 ° F)
107 ° C (225 ° F)
An optional open vent can be supplied on NORD reducers. The
open vent will be closed upon delivery to prevent oil leakage.
Before the reducer is put in service the open vent should be
activated by removing the sealing plug.
The Importance of Routine Oil Analysis
Filtered Vent
NORD may offer an optional filtered vent, which allows gases to
permeate, but does not allow dust and debris to pass through the
vent.
Routine oil analysis, sound lubrication practices, and good
tracking of oil performance trends as related to specific
equipment, will help establish proper lubrication maintenance and
change-out intervals. To maximize equipment reliability, NORD
Gear generally recommends a condition-based lubrication
maintenance program.
BIM 1013/2008/11
Page 4 of 10
www.nord.com
