SKF - Rolling Bearings

Lubricating greases
Diagram 1
The SKF traffic light concept
Do not use
Unreliable performance (use only for short periods)
Reliable performance, i.e. with predictable grease life
Temperature
LTL LTPL
HTPL HTL
LTL
LTPL
Low temperature limit
Low temperature performance limit
HTPL High temperature performance limit
HTL
High temperature limit
An amber zone also exists for low temperatures.
With decreasing temperature, the consistency
(stiffness) of grease increases and the
tendency of grease to bleed decreases. This
ultimately leads to an insufficient supply of
lubricant reaching the contact surfaces of the
rolling elements and raceways. In diagram 1,
this temperature limit is indicated by the low
temperature performance limit (LTPL). Values
for the low temperature performance limit are
different for roller bearings than for ball bearings.
Since ball bearings are easier to lubricate
than roller bearings, the low temperature performance
limit is less important for ball bearings.
For roller bearings, however, serious
damage can result when the bearings are
operated continuously below this limit. Short
periods in this zone, such as during a cold start,
are not harmful because the heat caused by
frictional heat brings the bearing temperature
into the green zone.
G
245