Spherical roller bearings carry heavy radial loads and certain axial loads in both directions. They have spherical, barrel-shaped rollers and are self-aligning to handle shaft misalignment and mounting problems. Spherical roller bearings contain two rings on the inner raceway, which house the rollers, and one sphered outer ring. Spherical roller bearings work similarly to self-aligning double-row ball bearings but can accommodate heavier loads. Most spherical roller bearings contain a steel or brass cage. These materials are used for their strength, durability, and resistance to a variety of environmental factors. Raceway, cage, and roller designs affect the performance of spherical roller bearings.
Double row spherical roller bearings have two rows of spherical rollers with common spherical raceway in outer ring. This internal bearing design enables mutual tilting of rings. Under load the spherical roller in some designs rest by their facial surface on fixed or floating center rib, guiding the rollers. Double row spherical roller bearings are not easily separable and are being mounted as a complete unit. They can accommodate great radial and simultaneously also axial loads in both directions. Double row spherical roller bearings have either cylindrical or tapered bore and are produced with machined brass cage (M) or with steel sheet cage (J).
Spherical roller bearings of most series are also available with a tapered bore (taper 1:12). Bearings with a tapered bore are usually fastened on the shaft by means of adapter sleeves or withdrawal sleeves. Bearings with a tapered bore can be mounted directly onto a tapered shaft seat. When mounting these bearings a defined radial clearance can be set.
The performance of a rolling bearing is highly influenced by the material which is used. The material of rings and rolling elements for rolling bearings is normally a low-alloy, through hardening chromium steel.
Spherical roller bearings have a lubricating groove and three lubricating holes in the outer ring to simplify lubrication. The bearings have the suffixW33.
Pressed cages are usually made of sheet. When compared with machined cages of metal they are advantageous in that they are lighter in weight. Bearings with a pressed cage have no cage suffix.
Machined cages of metal are used when requirements in cage strength are strict and temperatures are high. Solid cages are also used when lip guidance is required.
Mainfunctions of the cage:
Rolling bearing cages are subdivided into pressed cages and solid cages. Another distinguishing feature of the cages is the type of guidance. Most cages are guided by the rolling elements and have no suffix for the type of guidance. Those guided by the inner ring have the suffix B. When operating conditions are normal usually the cage design is taken which serves as the standard cage.
When double row spherical roller bearings are provided with a groove on perimeter and with three lubricating holes (W33), eventually three lubricating holes only (W20) , the lubricant can be fed straight into the bearing between two spherical roller rows. This enables to achieve better lubrication and higher operating reliability.
Double row spherical roller bearings are commonly manufactured in normal tolerance class PO. This symbol is not shown in bearing designation. Manufacture of bearings of higher tolerance class should be negotiated with the manufacturer. Limiting deviation values of dimensions and run tolerances are shown in ISO 492.
Currently manufactured double row spherical roller bearings are of normal radial clearance, which is not shown in bearing designation. On client's request for special purpose arrangements these bearings may be manufactured with radial clearance C2 (lesser than normal) or with radial clearance C3, C4 or C5 (greater than normal). Clearances values are shown in the next tables.
All bearings supplied for export under IKL brand must have international designation. International designation may have prefix, basic designation and suffex. The description of prefix, basic designation and suffex are given below. Also IKL bearings may have designation as perGOST.
Petroleum ether, petroleum, ethyl alcohol, dewatering fluids, aqueous neutral and alkaline cleaning agents can be used to clean rolling bearings. It should be remembered that petroleum, petroleum ether, ethyl alcohol and dewatering fluids are inflam mable and alkaline agents are - caustic. Paint brushes, brushes or lint-free cloths should be used for cleaning. Immediately after cleaning and the evaporation of the solvent, which should be asfresh as possible, the bearings must be preserved in order to avoid corrosion. Rolling bearings are heavy-duty machine elements with high precision. In order to fully utilize their capacity, mounting and dismounting should be taken into consideration when selecting the bearing type and design and when designing the surrounding structure. For the rolling bearings to reach a long service life, the use of suitable mounting aids as well as utmost cleanliness and care at the assembly site are essential requirements.
Blows with the hammer applied directly to the bearing rings must be avoided completely. In the case of non-separable bearings the mounting forces are applied to the ring which is to have a tightfit and which is first mounted. The rings of separable bearings however, can be mounted individually. Bearings with a maximum bore of approximately 80 mm can be mounted cold. The use of a mechanical or hydraulic press is recommended.
Individual bearings can be heated provisionally on an electric heating plate. The bearing is covered with a metal sheet and turned several times. A safe and clean method of heating rolling bearings is to use a thermostatically controlled hot air or heating cabinet. It is used mainly for small and medium-sized bearings. The heat-up times are relatively long. Induction heating devices are particularly suitable for fast, safe and clean heating.
Rolling bearings with a tapered bore are either fitted directly onto the tapered shaft seat or onto a cylindrical shaft with an adapter sleeve or a withdrawal sleeve. The resulting tight fit of the inner ring is measured by checking the radial clearance reduction due to the expansion of the inner ring or by measuring the axial driveup distance. Small bearings (up to approx. 80 mm bore) can be pressed with a lockout onto the tapered seat of the shaft or the adapter sleeve. A hook spanner is used to tighten the nut. It is advisable to use a hydraulic press for driving-up larger bearings or pressing them onto the sleeve.