Barrel Roller Bearings
- Compensation of misalignments
- Absorption of high radial and axial forces
- Used for shock loads
Barrel roller bearings (Sperical roller bearing, single row) are adjustable in angle and can compensate misalignments due to the spherical outline of outer and inner ring raceway and the barrel-shaped rolling elements. They absorb very high radial forces as well as axial forces from both sides, but they are not suitable for high speed needs. Barrel roller bearings cannot be disassembled and are suitable for use with very high shock loads.
Dimensions and Tolerances
KRW supplies barrel roller bearings with normal tolerance (PN) in accordance to DIN 620-2 (Tolerances for roller bearings) and ISO 492 (Radial bearings - Dimensional and geometrical tolerances). All other deviating or special tolerances must be specified with the order.
Design of a barrel roller bearing
Barrel roller bearings are self-latching radial bearings that cannot be disassembled. They can absorb highest radial forces as well as high axial forces from both directions. Barrel roller bearings can be delivered with cylindrical or tapered bore.
KRW supplies barrel roller bearings in normal clearance (CN) in accordance with DIN 620-4 (Rolling bearing tolerances) and ISO 5753-1 (Rolling bearings - Internal clearance), but they are also available in all clearance classes with restricted clearance or special clearance.
By default, KRW barrel roller bearings are equipped with a two-piece inner flange guided brass chamber cage (suffix: MB). Other cage designs are available on request or chosen for specific applications and labelled accordingly on the bearing.
Compensation of angular misalignments of a barrel roller bearing
Compensation of Angular Misalignments
Barrel roller bearings are suitable for compensation of misalignments between inner and outer bearing rings due to shaft deflections, angular errors and housing deformation. The admissible angular misalignment with static and circulating inner ring is 4°. Deviating angles are available on request or custom-designed.
KRW distinguishes between kinematic limiting speed nG and thermal reference speed nth. The kinematic limiting speed is a practical mechanical limit value and is based on the mechanical fatigue strength of the rolling bearing as a function of its installation situation and lubrication. The limit speed must not be exceeded even under optimum operating conditions without prior consultation with KRW.
The DIN ISO 15312 (Rolling bearings - Thermal speed rating) does not specify a thermal speed rating nth for these bearings.
Admissible Operating Temperatures
The admissible operating temperature of a bearing is limited by cage material, dimensional stability of the bearing components (ball race and rolling elements), as well as lubrication. By default, KRW bearings are stabilised up to 200°C (S1). KRW provides roller bearings for higher operating temperatures on request.
For dynamically loaded bearings
The service life formula according to ISO 281 L10 = (C/P)p for dynamically loaded bearings requires an equivalent load (P) from constant direction and size. To calculate P, calculation factors and the ratio of axial and radial load are required.
Equivalent Dynamic Bearing Load P
The equivalent bearing service life for the single row spherical roller bearings depends on the ratio Fa/Fr . The equivalent dynamic bearing load can be determined using the following formula:
For statically loaded bearings
Dynamic dimensioning loses its validity for bearings rotating at very low speeds (n x dm ≤ 4000 mm/min). The static load safety factor S0 is calculated as follows:
|S0||static load safety factor||[-]|
|C0||static load rating (from bearing chart)||[kN]|
|P0||equivalent static bearing load||[kN]|
|dm||mean bearing diameter [dm = (D+d)/2]||[mm]|
Minimum Radial Load
A minimum load is required for the reliable operation of a rolling bearing. If the minimum load is not reached, slippage may occur. The minimum radial load for barrel roller bearings is roughly assumed to be 2% of the static load rating C0 of the bearing. If the value falls below this value, please consult KRW Application Technology.