When a shaft deflects under load, or the housing is not perfectly machined, or the duty involves shock, the bearing that survives is usually a spherical roller bearing. Its outer ring carries a spherical raceway, the two rows of barrel-shaped rollers find their own line of contact, and the whole assembly tilts to follow the shaft without edge-loading. Nothing else in the radial family combines this much load capacity with this much tolerance for imperfect alignment.
This guide explains the self-aligning geometry that makes it work, decodes the CC, CA, E and EA cage designs, walks through the 213 to 241 series and their typical duties, and covers the fitting practice that keeps a spherical roller alive: C3 or C4 clearance, tapered adapter sleeves, high viscosity lubricant and a check on journal deflection.
- Self-aligning by geometry. The spherical outer raceway lets the inner assembly tilt, permitting typically 1 to 2.5 degrees of misalignment depending on the series, far more than any cylindrical or ball bearing.
- Cage design trades load against speed. The CC and E designs favour speed and the CA and EA designs favour load, with two-piece machined brass cages on the heavy versions.
- Choose spherical for deflection and shock. Crushers, paper machines, vibrating screens and long shafts that sag are its natural territory; cylindrical rollers cannot follow that motion.
- Fits and clearance are not optional. Spherical rollers are usually mounted with C3 or C4 clearance and an H, HE or AH adapter sleeve, because the same deflection that makes them useful also changes the fit.
Self-aligning geometry: why two rows work
A spherical roller bearing has two rows of rollers set at an angle to the axis, running on a common spherical outer raceway. The outer ring is a single piece with a concave path that matches the barrel shape of the rollers, so the inner ring together with both roller rows can tilt as a unit while the outer ring stays fixed. The contact angle of the two rows converges, and the rollers always find a line of contact rather than being forced to one edge.
The payoff is alignment tolerance. A single-row cylindrical roller tolerates perhaps 3 to 5 arc minutes before edge-loading starts; a spherical roller accepts 1 to 2.5 degrees, which is roughly twenty times as much. That is why a mill pinion with a sagging shaft, a conveyor pulley on a long span or a crusher on an uneven foundation uses a spherical roller: the deflection is absorbed as tilt instead of being turned into stress. The trade-off is speed. The two rows, the heavier cage and the higher friction of the tilted rollers all reduce the limiting speed relative to a cylindrical design of the same size.
The cage designs: CC, CA, E and EA
The suffix letters after the size describe the internal design and cage. They matter because they change the load balance and the speed ceiling.
- CC. A two-piece pressed steel cage, floating and guided by the rollers. It favours speed and runs cooler, and it is the usual choice for fan and blower applications where the load is moderate.
- CA. A one-piece machined brass cage guided by the inner ring, with a different internal geometry that increases the number of rollers. It favours load capacity and is standard for heavy duty.
- E. A redesigned pressed steel cage with a larger roller complement, giving higher capacity than the earlier CC at similar speed. It has largely replaced older designs in current catalogues.
- EA. The heavy-duty counterpart of E, with a machined cage and the largest roller complement, used for the highest loads and lowest speeds.
The practical rule is that E and EA carry more load than CC by roughly 10 to 20 percent in the same envelope, while CC runs at a higher speed. Always read the suffix, because two bearings that look identical can differ in capacity by a margin that changes the calculated life.
The 213 to 241 series and what the digits mean
Spherical roller designations follow the same bore and diameter series logic as other radial bearings. The first two digits identify the series, which fixes the width-to-diameter proportions and, with them, the load character. The final digits are the bore code. Larger series numbers are wider and shallower in proportion, which spreads the load over longer rollers.
| Series | Common bore range | Typical duty | Character |
|---|---|---|---|
| 213 | 60 to 120 mm | Compact self-aligning positions | Narrow, light duty |
| 222 | 25 to 260 mm | General heavy radial duty | The common default |
| 223 | 25 to 300 mm | Heavier radial duty, wider space | Wider than 222 |
| 230 | 90 to 500 mm | Large machines, moderate load | Narrow large-bore |
| 231 | 100 to 500 mm | Large machines, high load | Wider than 230 |
| 232 | 110 to 500 mm | Very high radial load | Wide, heavy |
| 240 | 150 to 560 mm | Very large bore, moderate load | Narrowest large series |
| 241 | 200 to 600 mm | Very large bore, heavy load | Widest large series |
A 22220 and a 22320 share a 100 mm bore but the 223 series is wider and carries more. The boundary dimensions themselves are standardised by ISO 15, so two brands offering a 22220 will match on d, D and B while their internal designs differ. Our self-aligning roller range lists the full dimensions and cage suffix on every record.
When to choose spherical instead of cylindrical
The choice between a spherical and a cylindrical roller is almost always decided by alignment and shock rather than by pure load. If the shaft stays parallel to the housing to within a few minutes of arc and the load is steady, a cylindrical roller is cheaper, faster and stiffer. As soon as any of three conditions appears, the spherical roller wins.
- Deflection. Long shafts, widely spaced bearings and thin housings all sag under load. The resulting angular error is exactly what the spherical geometry absorbs.
- Shock. Crushers, screens and hammers apply impact loads that a rigid line contact cannot distribute. The barrel roller and the two rows share the shock across a larger contact area.
- Contamination. In dusty or dirty duty the spherical roller's generous internal space and its tolerance of slight deflection keep it running where a precision cylindrical roller would edge-load and spall.
| Property | Spherical roller | Cylindrical roller | Tapered roller |
|---|---|---|---|
| Misalignment tolerance | 1 to 2.5 degrees | 3 to 5 arc minutes | 2 to 4 arc minutes |
| Radial capacity | Very high (two rows) | High (one row) | High |
| Axial capacity | Light, both directions | None in NU, light in NJ | Heavy, one direction each |
| Speed ceiling | Moderate | High | Moderate |
| Typical duty | Crushers, mills, screens | Motors, gearboxes | Hubs, pinions |
Fitting: clearance, adapter sleeves and fits
A spherical roller bearing is usually mounted on a tapered adapter sleeve rather than directly on a cylindrical shaft, because the sleeve both locates the bearing and sets the reduction in internal clearance as it is driven up the taper. Getting this right is the difference between a bearing that runs its full rating life and one that seizes in the first week.
C3 and C4 clearance
Spherical rollers normally run with C3 or C4 internal clearance rather than CN, because the deflection and the interference fit both reduce the running clearance and because the two rows need room to self-align. The clearance ranges come from ISO 5753 and are wider for the larger series. The clearance guide covers the numeric limits and how the fit closes them.
H, HE and AH adapter sleeves
An H sleeve fits a plain shaft and an HE sleeve fits a shaft with a thread already provided; both are secured with a locknut and a locking washer or clip. The AH sleeve is a withdrawal sleeve used where the bearing is mounted directly on a tapered journal or where the sleeve must be removed from the other side. The axial drive-up distance controls the clearance reduction, so it must be measured, not guessed. The locknut and adapter guide gives the torque and run-up values.
Speed limits and journal deflection
Two figures govern whether a spherical roller is the right answer at speed, and both are read from the catalogue rather than from memory.
Limiting speed
For a mid-size bearing such as a 22220 the limiting speed is typically around 4,000 rpm with grease and 5,000 rpm with oil. The two-row construction, the heavier cage and the friction of the tilted rollers all pull this figure below a single-row cylindrical roller of the same size. The speed and DN guide explains how the permissible speed is corrected for load and lubrication.
Permissible misalignment and deflection
The second figure is the permissible misalignment, 1 to 2.5 degrees depending on the series, beyond which the rollers ride on their edges and the life falls quickly. Journal deflection is the hidden variable. A shaft that sags by 0.1 mm over a 500 mm span tilts the inner ring by about 0.011 degrees - within the tolerance of a spherical roller but enough to matter to a cylindrical one. Estimating the deflection from the shaft deflection guide before choosing the bearing is the cheapest way to avoid an edge-loading failure.
How to select a spherical roller bearing
- Confirm the alignment budget. Estimate shaft deflection and housing error, and check it against the 1 to 2.5 degree permissible misalignment for the intended series.
- Size for load. Calculate the equivalent load and the L10 life against the basic dynamic rating, allowing for the shock factor in crusher and screen duty.
- Pick the series and cage. Use 222 or 223 for general duty, 230 to 241 for large bores, and choose E or EA over CC when load matters more than speed.
- Select clearance and mounting. Specify C3 or C4 clearance and an H, HE or AH adapter sleeve, then set the drive-up distance to the recommended reduction.
- Choose the lubricant and speed. Select a high viscosity, EP grease and confirm the limiting speed for the actual load and lubrication, using the grease selection guide.
Lubrication and failure modes
Spherical rollers are heavily loaded and often run in dirty conditions, so lubrication carries the load film and the contamination control at the same time. A high viscosity base oil with EP additives is the norm, and the grease must be able to survive the shock loads without being squeezed out of the contact.
| Failure mode | Typical cause | Guard |
|---|---|---|
| Edge spalling on one row | Misalignment or a cocked adapter sleeve | Measure run-out and drive-up |
| Rib and roller-end scoring | Insufficient lubricant film at shock load | Higher viscosity, EP grease |
| Inner ring creep | Loose fit on a soft or worn shaft | Adapter sleeve with correct fit |
| Overheating | Clearance closed by an over-driven sleeve | Check clearance after mounting |
The wear patterns map onto ISO 15243 failure terminology, and reading a removed bearing against that standard is the fastest way to tell an alignment fault from a lubrication fault. The failure mode guide works through the distinctions, and the industry pages show the duty profiles where each mode is most common.
Our FAG and spherical plain range pages sit alongside the self-aligning roller listings for comparison, and the tapered roller guide covers the family to choose when the axial load is heavy rather than the radial load.
Frequently asked questions
What is a spherical roller bearing used for?
It is used where heavy radial load combines with shaft deflection, housing misalignment or shock. Typical duties include crushers, vibrating screens, paper machines, mill pinions and large fans. The spherical outer raceway lets the bearing tilt 1 to 2.5 degrees, absorbing the misalignment a cylindrical roller cannot.
How much misalignment can a spherical roller bearing take?
Typically 1 to 2.5 degrees depending on the series and size, which is roughly twenty times the 3 to 5 arc minutes a cylindrical roller tolerates. Beyond the permissible value the rollers ride on their edges and fatigue life drops sharply, so the alignment must still be checked.
What do CC, CA, E and EA mean in spherical roller bearings?
They are cage and internal design codes. CC is a pressed steel cage favouring speed, CA is a machined brass cage favouring load, E is a redesigned pressed cage with more rollers, and EA is the heavy-duty machined version. E and EA carry more load than CC in the same envelope.
Why do spherical roller bearings use C3 or C4 clearance?
Because deflection, self-aligning tilt and interference fits all reduce the running clearance, and the two rows need room to move. CN clearance would close to zero in service. C3 is the usual default and C4 is used for the hottest or heaviest duty. The ranges come from ISO 5753.
What is an H or AH adapter sleeve?
An adapter sleeve mounts the bearing on a plain or threaded shaft and sets the clearance as it is driven up a taper. H fits a plain shaft, HE fits a threaded shaft, and AH is a withdrawal sleeve. The axial drive-up distance controls the clearance reduction and must be measured.
Spherical roller or cylindrical roller - which should I choose?
Choose cylindrical when the shaft stays parallel to within a few minutes of arc and the load is steady, because it is faster and stiffer. Choose spherical when the shaft deflects, the housing is imperfect or the duty involves shock or contamination. The deciding factor is almost always alignment, not load.