They create a slight frictional drag, but seal out contaminants while helping to retain grease within the bearing. Standard seals are suitable for temperatures up to 225 F. Bearing Lubrication Oiled bearings are generally used in gravity applications requiring a low coefficient of friction. The temperature range of standard oil is 0 to 200 F. Grease Packed bearings are generally used in powered applications. They are suitable for higher humidity applications. Regreasable bearings share the same features as grease packed bearings and, in addition, are designed to accept more grease through a grease fitting located on the end of the axle.
Regreasable bearings have either a drilled inner race or an extended back closure.
Axle Specification Axles are typically hexagonal to avoid rotation in the frames and to prevent the inner race in the bearings from rotating on the axle, however, round axles are also available. Larger sized round axles are kept from rotating by use of a keeper bar. Bearings used on these larger axles usually have set screws or eccentric locking collars to prevent inner races from rotating. Pin or Ring retained axles have a hole drilled in each end of the axle to accommodate cotter pins or hog rings. Axles can also be drilled for pressure lubrication of bearings.