Split FAG spherical roller bearings
Features
Spherical roller bearings are double row units comprising solid outer rings with a concave raceway, solid inner rings and barrel rollers with cages. The symmetrical barrel rollers orient themselves freely on the concave outer ring raceway. As a result, shaft flexing and misalignment of the bearing seats are compensated.
In split spherical roller bearings, the inner ring, outer ring and cage with the roller set are split in half. The split bearing rings are held together by screws.
Cost savings
Split spherical roller bearings are principally used where the replacement of unsplit spherical roller bearings would require costly additional work, involving the removal of gears or couplings, the dismounting of drives or the dismantling of shaft power trains. The use of split spherical roller bearings reduces the downtime of machinery and plant.
In new designs too, split spherical roller bearings can give cost savings in many cases since the plant can be simplified and the assembly work required is reduced. Due in particular to the reduced downtime, the mounting of split spherical roller bearings gives a significant reduction in mounting costs, ➤ Figure.
Cost elements in bearing replacement
Replacement for bearings with adapter sleeve
Split spherical roller bearings can generally be mounted instead of unsplit spherical roller bearings with adapter sleeves. The preconditions for replacement are that the outside diameter, outer ring width and diameter of the shaft seat are identical and that the bearings are suitable for the load case, ➤ Figure.
Simple bearing replacement
Mounting in split plummer block housings
Split split spherical roller bearings can in many cases be mounted in our split plummer block housings. At difficult to access locations in particular, this combination of a split bearing and split housing gives considerably easier mounting of bearings, ➤ Figure.
The housings are specifically designed for the location of spherical roller bearings. Split FAG plummer block housings and the associated bearings form bearing arrangement units that can be matched, through the specific selection of seal design, lubrication type and bearing mounting, to a wide range of requirements.
In order to ensure selection of the correct combination of housing and bearing when using split bearings, please contact Schaeffler.
Split spherical roller bearing in a split SNS housing with split labyrinth seal
Further information
TPI 231, Split Plummer Block Housings SNS
TPI 175, Split Plummer Block Housings SNV..
Application examples
A common application for split spherical roller bearings is on shafts supported at several points and difficult to access mounting locations. Typical areas of application include conveying equipment, materials processing plant, ventilation plant, rolling mills, ships and paper machinery.
Application examples in mining and materials processing, ➤ Figure and ➤ Figure:
- Bucket wheel excavators and reclaimers
- Winches and sheaves, drive and transmission shafts
- Worm conveyors, bucket conveyors and conveyor belts
- Mixing and stirring plant, mills and crushers
- Sintering plant, rotary kilns
- Fans and ventilators, dust extraction plant.
Bearing arrangements in comminution and processing plant
Drive bearing arrangements in conveying and transport equipment
Application examples in the pulp and paper industry, ➤ Figure and ➤ Figure:
- Fans and ventilators
- Mixing and stirring plant
- Dryer rolls
- Drive and transmission shafts
- Conveying equipment
- Comminution machinery.
Bearing arrangements in fans and ventilators
Mounting of a large split spherical roller bearing
Product range
The comprehensive range contains split spherical roller bearings for metric shaft diameters from 55 mm to 630 mm and for inch size shafts from 2 3/16 inch to 16 inch.
In most cases, the outside diameter, outer ring width and diameter of the shaft seat are identical to those of standard spherical roller bearings of series 222, 230, 231, 239, 240 and 241 with appropriate adapter sleeves.
Bearing design
Split spherical roller bearings have a cylindrical bore.
The internal construction of most split spherical roller bearings was carried over from our proven spherical roller bearing, ➤ Figure.
Internal construction of bearings with integrated locking rings
The bearings have a split solid cage made from glass fibre reinforced polyamide or brass, see Catalogue HR 1, Rolling Bearings.
Split spherical roller bearings have the normal tolerances of unsplit radial bearings and the normal internal clearance of unsplit spherical roller bearings with a cylindrical bore (ISO 492:2014). In most split spherical roller bearings, the locking rings are integrated in the inner rings, ➤ Figure.
Split spherical roller bearing with split solid cage made from glass fibre reinforced polyamide or brass, with integral locking rings
If there are large differences in temperature between the shaft and inner ring halves, which can occur for example in dryer rolls for paper machinery, bearings with separate locking rings are more suitable, ➤ Figure.
Split spherical roller bearing for special applications with separate, split locking rings
Design and safety guidelines
Load carrying capacity
Due to the screw connection in the outer ring, the pitch circle for the rolling element set is smaller than that of an unsplit spherical roller bearing. As a result, the load carrying capacity of split spherical roller bearings is lower by comparison. Since they contain the maximum number of rollers with the largest possible dimensions, they can nevertheless achieve a high load carrying capacity.
The overrolling of the joints is taken into consideration in calculation of the equivalent dynamic load by applying the shock factor 1,1. Dimensioning is carried out according to the normal calculation method from Catalogue HR 1, Rolling Bearings.
Speed suitability
The values take account of the cage strength and the vibrations generated through overrolling of the joints. If the limiting speeds are exceeded, consultation with Application Engineering is required.
Fits
In order that the inner rings have the necessary tight fit once the screws have been tightened, the shaft must be machined to between h6 and h9. These shaft tolerances are the same as those normally used with unsplit bearings located by means of adapter sleeves. The housing bore is normally machined to H7 or H8.
Lubrication
Split spherical roller bearings are normally lubricated using grease. The lubrication intervals correspond to those of unsplit bearings. Split spherical roller bearings can also be relubricated via a groove and holes in the outer ring.
The use of split spherical roller bearings in conjunction with the automatic relubrication devices FAG CONCEPT8 or FAG CONCEPT2 is particularly effective. Through controlled relubrication, a sufficient quantity of fresh lubricant is continuously supplied to the contact points of the rolling bearing. This results in a significant increase in bearing life. The devices extend the lubrication and maintenance intervals and prevent undersupply or oversupply of lubricant. Plant downtime and maintenance costs are reduced as a result. The sparing and environmentally friendly use of lubricants contributes to higher cost-efficiency, ➤ Figure.
Plummer block housing SNS with automatic lubricator FAG CONCEPT8
Further information
TPI 252, Automatic Relubrication Devices..
FAG SmartCheck
Condition monitoring and diagnosis of split spherical roller bearings can be carried out using FAG SmartCheck. This is a cost-effective, innovative online measuring system for the continuous monitoring of machine and process parameters on a decentralised basis.
FAG SmartCheck allows recording of vibrations and process parameters such as speed and temperature and thus facilitates monitoring of the bearings. The automatic alarm threshold adjustment allows a reliable alarm system. The alarm system can be implemented in a WLAN on a smartphone by means of the free-of-charge SmartCheck APP.
Split FAG plummer block housings SNS are equipped as standard with a connection point to which FAG SmartCheck can be screw mounted. If a suitable connection point with a hole is not present, FAG SmartCheck can be attached by means of adhesive or a magnet.
Further information
TPI 214, FAG SmartCheck..
Mounting of split spherical roller bearings
The following pictures give a summary of the operations in the mounting of split spherical roller bearings. Each bearing is supplied with a comprehensive mounting manual, ➤ Figure to ➤ Figure.
Support the rotor
Remove the housing cover
Dismount the old bearing
Insert the outer ring half in the lower housing section
Mount the remaining parts
Lower the shaft
Mount the upper housing section
