Indexing Roller Units

SKF indexing roller units are basically double row full complement cylindrical roller bearings (fig 1). In a few cases they are based on four-row full complement cylindrical roller bearings (fig 2). The very thick-walled outer ring has three integral flanges. The highly wear-resistant outside diameter is cylindrical, being relieved towards the side faces, or the transition takes the form of a chamfer. The inner ring is in two halves, each of which has an integral flange, which is designed to enable the units to carry heavy axial loads in addition to radial loads. O-rings inserted in a groove in the inner ring flange shoulders prevent contaminants from entering the bearing and lubricating grease from escaping; they also make the bearing a non-separable unit.

Indexing roller units were originally developed for use on the continuous furnaces of sintering and pelletising plants (fig 3). These ready-to-mount units are also suitable for all applications where heavy loads have to be accommodated and the direction of rotation is frequently reversed, or where rotational speeds are low.

Tolerances SKF indexing roller units are produced to Normal tolerances corresponding to ISO 492:1994.

Internal clearance Indexing roller units up to 120 mm bore diameter are produced with C3 radial internal clearance and the larger sizes with Normal radial internal clearance which corresponds to that specified for needle roller bearings and cylindrical roller bearings.

The clearance values will be found in the table and conform to ISO 5753:1991.

Lubrication

SKF indexing roller units are filled with the SKF lubricating grease LGEV 2. This is a high-quality lithium/calcium base grease with a highly viscous mineral base oil and contains molybdenum disulphide and graphite. Further information will be found in table 1.

The units are designed for maintenance-free operation, but it is possible to relubricate them via lubrication grooves in the flangeless side faces of the inner ring halves (fig 4).

Load carrying capacity In contrast to normal rolling bearings where the outer ring is supported over its whole circumference by the housing bore, load is applied to the indexing roller units via a small contact area on the outer ring cylindrical surface. Deformation of the outer ring leads to changes in the load distribution in the unit and the load carrying capacity is reduced. The basic load ratings given in the product table under the heading “Roller” take this influence into account.

With reference to the strength of the outer ring and the deformation produced in it, maximum permissible radial dynamic and static bearing loads are given in the product table in addition to the load ratings. The maximum static load which can be applied to the indexing roller is the smaller of the two values of F0r and C0.

Supplementary designations The designation suffixes used to identify certain features of SKF indexing rollers are explained in the following.

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