Page 317 - The Tribology Handbook

Greases c4

Table 4.5 Selection of greases for rolling bearings

.................................................................. SPEED ..................................................................

Vev slow Slow Average Fast Very fast
(under 500 r.p.m.) (500 7.p.m.) (1000 7.p.m.) (2000 r.p.m.) (over 2000 7.p.m.)
BEARING SIZE
Micro (1-5 mmi) .......................................... A specially selected ultra-clean grease required ..........................................
-
~~
Miniature ....................................... Normally aviation greases are used, e.g. XG 287 type .......................................
(under 10 mm)
Small (20-40 mim) Calcium Calcium or lithium Lithium (Lithium (XC 271 type)) Sodaxalcium
Medium (65 mm) (LG 280 type) (XG 271 type) (XG 271 type) (Lithium (XG 274 type)) oil type
Large (100 mm) Lithium/oil (XG 274 Lithium (XG 274 Lithium Lithium -
or XG 271 type) type) (XG 274 type) (XG 274 type)
Very large (200 Calcium or Lithium Lithium Lithium or soda-calciurn -
mm or more) lithium (XG 274 type) (XG 274 type) (XG 274 type)
____
Note for definiiion of these ‘types’ refer to Table 4 I

If the bearing is heavily loaded for its size, i.e. approach- In general it is advisable always to have good anti-rust
ing the maker’s recommended maximum, or is subject to properties in the grease, but since most commercial greases
shock loading, it is important to use a good extreme- available incorporate either additives for the purpose or
pressure grease. Likewise a heavily-loaded plain bearing are in themselves good rust inhibitors, this is not usually a
will demand a good EP grease. major problem.

Table 4.6 Uses of greases containing fillers

Filler Graphite Molybdenum disulphide Metallic powder*

GREASE
Calcium Plain bearings Not commonly used High temperature thread lubricant
Sliding friction andior localised high see lithium Electrically conducting?
i emperatures

Lithium As for calcium but not commonly used Sliding friction Not commonly used
Anti fretting
Knuckle or ball joint
Reciprocal motion
Rolling bearings
Care must be taken with localised high
temperatures
Clay As for calcium As for calcium As for calcium

* Metal powder is normally zinc dust, copper flake or finely-divided lead.
t Useful where a current must be passed through rolling bearing from axle to outer race.
Note: filled greases should not normally be used in rolling bearings. Finally, it should be remembered.that all of the above remarks refer to
typical greases of their type. It is quite possible by special manufacturing techniques, use of specialised additives, etc., to reverse many of
the properties eiiher by accident or design. The grease supplier will always advise on any ofthese abnormal properties exhibited by his grease.

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