Split Spherical Roller Bearings

Split spherical roller bearings (fig) are primarily used for bearing positions which are difficult to access such as on long shafts which require support at several positions, or on cranked shafts. Their use is also beneficial where non-split bearings would require considerable time and effort for maintenance and more particularly for replacement; this would also cause long and expensive, or perhaps even inadmissibly long machine downtime. Split spherical roller bearings offer the optimum solution to such problems. The main application areas include conveyor equipment, long multiple-supported shafts and large ventilation plants (fig).

SKF split spherical roller bearings are produced to order. The design is tailored to the particular application and, for cost reasons, is generally based on available bearings of standard design. The selection of bearings shown in the tables is intended to illustrate the SKF manufacturing capability; these bearings have been made. Before finalising a bearing arrangement design incorporating a split spherical roller bearing it is advisable to consult the SKF application engineering service.

Split bearing units for continuous casting plant SKF has developed ready-to-mount split bearing units specifically designed for use on the drive rollers of the cooling zone of continuous casting plant. The special housings are of cast steel and are water cooled. The housing top with its integral cooling chamber has a low sectional height because the standard design incorporates only one outer ring half which is positioned in the base of the housing. The spherical roller bearing of the unit normally consists of two inner ring halves with lubrication groove and holes, four clamping ring and cage halves, one outer ring half and two lamellar sealing rings with one split. The inner ring division is at an angle to the bearing axis.

Further information on SKF split bearing units for continuous casting plant will be sent on request.

Split bearing units for continuous casting plant

SKF has developed ready-to-mount split bearing units specifically designed for use on the drive rollers of the cooling zone of continuous casting plant. The special housings are of cast steel and are water cooled. The housing top with its integral cooling chamber has a low sectional height because the standard design incorporates only one outer ring half which is positioned in the base of the housing. The spherical roller bearing of the unit normally consists of two inner ring halves with lubrication groove and holes, four clamping ring and cage halves, one outer ring half and two lamellar sealing rings with one split. The inner ring division is at an angle to the bearing axis.

Further information on SKF split bearing units for continuous casting plant will be sent on request.

Design As already mentioned, SKF split spherical roller bearings are based for the most part on non-split bearings of standard design. Consequently they represent state-of-the-art engineering. All the split bearings have a cylindrical bore and an annular groove and lubrication holes in the outer ring to facilitate efficient lubrication. The joins of the inner ring are at an angle to the bearing axis in order to guarantee uninterrupted overrolling of the join. The bearing rings and cage are divided in the middle and the ring halves are held together either by screws or by clamping rings.

BSR.1 design

Inner ring halves screwed together. Two integral retaining flanges. Split inner ring centred machined brass cage (fig).

BSR.2 design

Inner ring with two integral retaining flanges. Loose split clamping rings. Split inner ring centred machined brass cage (fig).

BSR.3 design

Inner ring with two integral retaining flanges. Loose split clamping rings. Split machined pin-type cage of steel (fig).

Dimensions

The dimensions of split spherical roller bearings have not been standardized. However, the bore and outside diameters of the standard bearings on which the split bearings are based do conform to ISO 15:1998.

Tolerances

SKF split spherical roller bearings are produced to Normal tolerances except for the tolerances of the bore diameter and inner ring width. The normal tolerances are in accordance with those specified in ISO 492:2002.

Internal clearance

SKF split spherical roller bearings are manufactured with Normal or C3 radial internal clearance according to ISO 5753:1991.

Misalignment

Split spherical roller bearings are self-aligning and permit angular misalignments of the shaft relative to the housing of some 1 to 1,5�.

Shaft and housing tolerances

For split spherical roller bearings which are subjected to alternating loads and rotation, and to relatively heavy loads (P > 0,12 C), it is recommended that the shaft seat be machined to tolerance h6. For applications where the load is lighter (P < 0,12 C) and of constant direction, seats machined to tolerance h7 are also acceptable. The seat tolerance normally applied for adapter sleeve mounted bearings, h9/IT7, can be used where loads are still lighter and speeds low.

The recommended housing bore seat tolerance is H7. For converters, split spherical roller bearings are often used as replacements for the non-split spherical roller bearings which were originally fitted. In such cases the journal seats are to tolerance r7 and the housing bore seats to E7. The replacement split bearings are specially produced with the appropriate lager bore tolerances to match.

Speeds

The vibrations caused by the overrolling of the split join limit the speeds at which split bearings can be operated to approximately 50% of the speed ratings for standard non-split spherical roller bearings. As it is not possible to give general guideline values, it is advisable to contact the SKF application engineering service, particularly if it is desired to operate at relatively high speeds.

Load carrying capacity

The load carrying capacity of split spherical roller bearings is reduced compared with non-split bearings. The split cage means that fewer rollers can be incorporated.

The over-rolling of the join also reduces load carrying capacity. This is taken into account by applying a factor describing the type of operation when calculating the equivalent dynamic bearing load; see under “Equivalent dynamic bearing load”.

Equivalent dynamic bearing load

For split spherical roller bearings

P = b (Fr + Y1Fa) when Fa/Fr = e

P = b (0,67 Fr + Y2Fa) when Fa/Fr > e

The values of the factors e, Y1 and Y2 are given in the product table. The following guideline values of b have been established to take into account the type of operation and the demands of smooth running.

b = 1,1 … 1,3 for machines operating at constant speeds with high demands on smooth running and operational reliability

b = 1,3 … 2 for machines which are subjected to light shock loads and imbalance loads

b = 2 … 4 for machines which are subjected to heavy shock loads or where oscillating movement occurs

Equivalent static bearing load

For split spherical roller bearings

P0 = Fr + Y0Fa

The values of factor Y0 will be found in the product table.

Spherical roller bearings | Open bearings | Sealed bearings | Bearings for vibratory applications | SKF Energy Efficient (E2) spherical roller bearings | Split spherical roller bearings