Page 119 - Rollingbearings

Selecting a suitable grease
Mechanical stability Diagram 4
During rotation of a bearing, the grease is The SKF trafic light concept
mechanically worked and a change in con-
sistency may result. This property is known ← Do not use
as the mechanical stability of the grease and
is measured in standardized tests, ← Unreliable performance (use only for short periods)
ASTM D217 and/or ASTM D1831. Greases ← Reliable performance, i.e. with predictable grease life
that soften may leak from the bearing cavity.
Those that stiffen may restrict bearing rota-
tion or limit oil bleeding. The mechanical
stability should not change drastically if Temperature →
operation is within the speciied temperature
range of the grease. LTL LTPL HTPL HTL
LTL Low temperature limit
Corrosion protection
LTPL Low temperature performance limit
HTPL High temperature performance limit
In applications where water or condensation
is present, the corrosion inhibiting properties HTL High temperature limit
of the grease are very important. The corro-
sion inhibiting ability is determined by the
properties of the rust inhibitor additive and/ Diagram 5
or the thickener type. The performance is SKF trafic light concept – SKF greases 1)
measured using the EMCOR test, ISO 11007.
For applications where water or condensa-
tion is present, the rating should be 0-0. SKF Grease Temperature range
designation
–50 0 50 100 150 200 250 300 °C
The SKF trafic light concept
LGMT 2
for grease temperature
LGMT 3
performance
LGEP 2
The temperature range over which a grease
LGWA 2
can be used depends mainly on the type of
base oil, thickener and additives. The rele- LGFP 2 Lubrication
vant temperature limits are schematically
LGGB 2
illustrated in diagram 4 in the form of a
double trafic light, with additional details LGBB 2
provided in diagram 5. LGLT 2 B.4

LGWM 1
• The low temperature limit (LTL) is deter-
mined by the low temperature frictional LGWM 2
torque test according to ASTM D1478 or LGEM 2
IP 186. The LTL is determined by the tem-
perature at which the starting torque is LGEV 2
equal to 1 000 Nmm and the running LGHB 2
torque is 100 Nmm. LGHP 2
• The high temperature limit (HTL) is the
LGET 2
temperature at which a grease loses its
consistency and becomes a luid. It is LGED 2
determined using the dropping point
LGFQ 2
(ISO 2176).
–60 30 120 210 300 390 480 570 °F

1) The low temperature performance limits (LTPL) are valid for roller bearings
LTPL values for ball bearings are approx 20 °C (35 °F) lower

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