The cylindrical roller skf bearings joined by two rows have a maximum number of rollers, which allows them to withstand very high radial loads. However, they can not operate at speeds as high as the cylindrical roller bearings with cage. The SKF roller bearings cylindrical joined two rows are available in standard version under four different types: three types of bearings and open with a type joints. All these bearings are made of and inseparable elements with an outer ring and ring groove with three holes to facilitate lubricating grease.
Roller-type NNCL have an inner ring with three shoulders and a fixed outer ring without shoulder. A segment of judgement, inserted in the outer ring between the rows of rollers, maintains the various components of working capital assembled. An axial displacement of the tree in relation to the bearing is possible in both directions. These bearings can be used as landing free.
Roller-type NNCF are equipped with three shoulders fixed on the inner ring and a shoulder fixed on the outer ring which help guide the shaft axially in a sense. A segment of arrest is inserted in the outer ring, the side opposite to the shoulder fixed, to avoid rolling to disassemble.
Roller-type NNC are equipped with an inner ring identical to that of NNCL and bearing NNCF. Their outer ring into two parts assembly is maintained by a restraint that should not be loaded axially. Its two parts are identical and it is equipped with a shoulder fixed which helps guide the shaft axially in both directions.
The bearings NNF series NNF 50 and 3194 (00) are still bearing joints on both sides and lined with grease. Their inner ring into two parts has three fixed shoulders and is maintained assembled by a segment of judgement. The outer ring has a central shoulder fixed. These bearings can be used to guide the shaft axially in both directions. The relatively large distance between two rows of roller bearings also allows couples to bear spill.

The outer ring of a rolling NNF, narrower than the inner ring of a millimeter, has two slots for segments of judgement on its outer surface. The spacers between the faces of the inner ring and neighbouring elements are superfluous and in blocks by example

Special Type NNB.These bearings have three fixed shoulders on the inner ring and an outer ring without broad-shouldered This special bearings are designed for mounting levels of requiring free movement axial important in the rotation.