The decisive difference is how the machine moves under load. A joint may need to articulate, while a shaft may need to keep rotating with low friction. Identify that job first, then compare load, misalignment, speed, maintenance and the installed geometry.
Choose a spherical plain bearing when a loaded joint mainly oscillates, tilts or articulates and must tolerate angular misalignment at relatively low sliding speed. Choose a ball bearing, typically a deep groove ball bearing, when a shaft mainly makes continuous revolutions and low friction, rotational speed and smooth running matter. Neither choice is correct until the exact load, movement, alignment, lubrication and fits have been checked.
A request for “a bearing for a 20 mm shaft” sounds specific, but it leaves out the fact that changes the bearing family: does the shaft turn through complete revolutions, or does the joint move back and forth through a small angle while carrying load?
From a factory drawing-review perspective, that question comes before the catalogue search. If the mechanism is a cylinder eye, linkage or pivot, articulation may be the job. If it is a motor shaft, fan or rotating spindle, rolling motion may be the job. A shared bore diameter does not make the two designs interchangeable.
1. Start with the motion inside the bearing
Spherical plain bearing
A convex spherical surface on the inner ring slides against a matching concave surface in the outer ring. The broad sliding interface transfers load while allowing the inner ring to swivel and tilt. There are no balls or rollers between the rings.
Rolling ball bearing
Balls roll between formed raceways in the inner and outer rings. A cage usually keeps the balls spaced. This comparison uses the common single-row deep groove design as the reference; angular-contact and self-aligning ball bearings have different capabilities.
The SKF spherical plain bearing catalogue describes this bearing family as ready-to-mount components for multidirectional self-aligning movement, including oscillating, tilting and slewing movement at relatively low speed. SKF's deep groove ball bearing guidance describes that rolling design as low-friction, high-speed capable and able to accept radial and axial load in both directions.
Those are family-level directions, not permission to skip calculation. A spherical plain bearing still has limits on contact pressure, sliding velocity and angle. A ball bearing still needs adequate load, lubrication, clearance, fit and alignment.
2. Spherical plain bearing vs ball bearing at a glance
| Decision factor | Spherical plain bearing | Deep groove ball bearing | What the engineer should verify |
|---|---|---|---|
| Contact | Spherical surfaces slide directly or across a liner | Balls roll between ring raceways | Sliding pair or rolling-bearing design, surface finish and lubricant |
| Natural motion | Oscillation, tilting, articulation and slow slewing | Continuous rotation | Full revolutions or oscillation angle, frequency and dwell time |
| Angular misalignment | Built into the spherical sliding geometry, within the stated angle | Limited in a standard deep groove design | Static and dynamic misalignment after shaft and housing deflection |
| Friction and speed | Sliding friction produces heat as pressure and speed rise | Rolling contact generally supports lower friction and higher rotational speed | Speed, starting torque, heat removal and lubricant regime |
| Load review | Check contact pressure, sliding velocity, load direction and sliding material | Check dynamic or static equivalent load, minimum load, speed and rating life | Normal, peak, shock, reversing, radial and axial components |
| Maintenance | Either relubricated steel-to-steel or a self-lubricating liner, by series | Open, shielded or sealed and greased arrangements, by series | Lubrication access, contamination, seal material and inspection plan |
| Precision outcome | Useful articulation, with clearance and wear managed for the joint | Useful rotational guidance, with clearance or preload selected for the shaft | Allowed play, runout, torque and end-of-life criterion |
The ball-bearing column refers to a typical single-row deep groove design. Do not apply it unchanged to self-aligning, angular-contact or thrust ball bearings.
3. Small-angle oscillation is not automatically easy duty
Engineers sometimes treat a small movement as harmless because total travel is short. The contact does not see it that way. Under load, a spherical plain bearing slides across part of its surface. In a rolling bearing, a very small repetitive movement may keep the rolling elements working over the same narrow raceway zones.
SKF's explanation of bearing damage under ISO 15243 states that false brinelling can occur where rolling elements and raceways experience small oscillatory motion or vibration. The wear pattern depends on load, oscillation or vibration intensity, and lubrication. That does not mean every oscillating mechanism must use a plain bearing. It means ordinary rolling-bearing life logic may be incomplete for a short-stroke joint.
The opposite warning matters too. Steel-to-steel spherical plain bearings can struggle to move fresh lubricant into the loaded zone when the oscillation angle is small and the load direction stays constant. The SKF spherical plain bearing catalogue identifies this as a critical condition for that sliding pair. A lubrication groove, grease port and calendar interval do not solve the problem unless grease actually reaches the working zone.
4. Continuous rotation usually points toward a ball bearing
When a shaft completes repeated revolutions, rolling contact has the natural advantage. Deep groove ball bearings are designed for low friction and high rotational speeds, and they can guide a shaft while carrying radial load plus an axial component in either direction. Exact capability still varies with size, cage, seals, clearance, lubricant and mounting.
A spherical plain bearing can rotate in some applications, but every revolution is sliding travel. More load and sliding speed increase frictional energy and heat at the interface. The application therefore needs the permissible pressure and sliding-velocity envelope for the exact material pair. Calling a design “maintenance-free” does not remove that limit.
There are legitimate gray areas: slow rotating joints, indexing tables, intermittent slewing and combined swivel-plus-rotation. In those cases, classify the full motion rather than forcing the assembly into an “oscillating” or “rotating” label. The cycle may contain acceleration, reversal, dwell and shock that change the governing condition.
5. Misalignment: articulation is not the same as a self-aligning rolling bearing
A spherical plain bearing changes angle through its working sliding surfaces. That articulation can accommodate assembly error, structural deflection or an intentional joint angle, provided the angle remains within the bearing geometry and the surrounding shoulders do not interfere.
A standard deep groove ball bearing is comparatively rigid. SKF's rolling-bearing selection guidance notes that rigid bearing types accommodate only the misalignment allowed by their internal clearance, and that misalignment can reduce service life.
A self-aligning ball bearing is a different answer. It has two rows of balls and a common sphered outer-ring raceway, allowing angular misalignment while retaining rolling contact. It may suit a continuously rotating shaft with mounting error or shaft deflection. It is not a drop-in substitute for a loaded linkage joint, and it should not be confused with a spherical plain bearing just because both use the word “spherical” or “self-aligning.”
6. “Which carries more load?” has no honest one-line answer
The spherical plain bearing has a broad sliding contact area. The ball bearing distributes load through rolling contacts between balls and raceways. That geometric difference matters, but it does not produce one universal winner.
For spherical plain bearings, selection can require the equivalent load, specific bearing load, sliding velocity and a product-specific rating-life or permissible-range method. SKF also distinguishes static conditions from dynamic ones: once the loaded surfaces slide through oscillation or tilting, wear becomes part of the dynamic review. For ball bearings, rating life calculations use the relevant rolling-bearing load ratings and equivalent loads, with corrections or checks for speed, lubrication, contamination, reliability and minimum load.
Even two numbers both labelled “dynamic load rating” may not mean the same thing across a plain-bearing table and a rolling-bearing table. Schaeffler's spherical plain bearing technical catalogue ties permissible operation to sliding material, specific load and sliding velocity. Compare the final application calculation, not the largest printed number.
7. When the mechanism calls for spherical sliding, Dongzhou has several routes
Dongzhou's current catalogue pages focus on radial spherical plain bearings rather than rolling ball bearings. This matters commercially: we should not recommend our own product family until the motion says it belongs there. When it does, the next choice is not merely a part number. It is the sliding system.
| Dongzhou family | Construction listed on the current page | Service direction | Useful RFQ question |
|---|---|---|---|
| GE UK | Metric, two-piece, steel-to-PTFE composite, pressed outer ring and chromium-plated inner spherical surface | Maintenance-free spherical sliding | Does the load, sliding velocity and environment suit the PTFE liner? |
| GE E / GE ES / GE ES-2RS | Steel-to-steel, phosphated rings and an axially split outer ring; ES adds lubrication paths and 2RS adds two seals | Maintenance-required spherical sliding | Can the installed housing feed grease and protect the loaded zone? |
| COM / HCOM | Inch-dimension steel-to-steel family with carbon-steel outer ring, GCr15 hard-chromium-plated inner ring and lubrication grooves and holes | Maintenance-required inch route | Are inch envelope, fit, grease path and articulation angle confirmed on the drawing? |
| G PW | PTFE-lined family with brass H62, carbon-steel or stainless outer options and GCr15 or 440C inner options by designation | Maintenance-free material options | Which exact outer and inner material suffix matches the corrosion environment? |
Source: Dongzhou live product pages checked September 10, 2026. The pages show load figures without a visible unit label, so no load value is repeated here. Confirm final specifications at quotation.
8. The drawing review should begin before part-number matching
When we receive a bearing code without a machine sketch, we can compare nominal dimensions. We cannot see whether the bearing family suits the mechanism. A useful review adds motion arrows and load arrows to the section drawing.
-
Describe the motion
Full rotation, oscillation or tilt; total angle; speed or frequency; dwell time and duty cycle. -
Separate the loads
Radial and axial components, normal and peak values, direction changes, shock and the units used. -
Define the envelope
Shaft diameter, housing bore, available width, shoulders, chamfers and neighboring-part clearance at extreme angles. -
State the fits
Shaft and housing materials, tolerance classes, wall thickness, retention method and assembly sequence. -
Show the environment
Dust, water, washdown, chemicals, corrosion, temperature and how seals are protected. -
Set the service target
Lubrication access, maintenance interval, allowable play or torque, life target and inspection method.
This is where a factory-side review becomes useful. Dongzhou's company page states that the business was established in 2006, uses more than 300 precision machining machines and professional testing instruments, and develops non-standard products from drawings or samples. A sample can reveal geometry and wear marks. It cannot reveal the machine's peak load or motion cycle, so the owner's operating data still has to accompany it.
If the selection remains spherical plain, continue with our spherical plain bearing design and selection guide. If the joint terminates in a threaded linkage rather than a separate housing, compare the connection in the rod end bearing applications guide.
Dongzhou drawing review
Show us what moves before asking what fits
On one section drawing, mark whether the shaft rotates through 360 degrees, oscillates through a stated angle or tilts under load. Add the radial and axial forces, cycle rate, housing and shaft fits, lubricant route and environment. Dongzhou can then check whether a catalogue spherical plain bearing is a sensible starting point and review non-standard geometry from a supplied drawing or sample.
Frequently asked questions
What is the main difference between a spherical plain bearing and a ball bearing?
A spherical plain bearing transfers load through matching spherical sliding surfaces. A ball bearing separates its rings with rolling balls and raceways. The plain bearing is commonly selected for loaded oscillation, tilting and articulation at relatively low sliding speed. A deep groove ball bearing is commonly selected for continuous shaft rotation, low friction and higher rotational speed.
Can a spherical plain bearing rotate continuously?
Some spherical plain bearing designs can accommodate rotation, but continuous rotation creates sliding speed and heat that must remain within the exact bearing's limits. Do not approve the substitution from bore size alone. Check the sliding pair, load, speed, lubrication, temperature and required life with the manufacturer's calculation.
Is a spherical plain bearing a type of ball bearing?
No. The rounded inner ring can make a spherical plain bearing look like a ball in a race, but there are no rolling balls between the inner and outer rings. Its working surfaces slide. A ball bearing uses balls as rolling elements between raceways.
Which bearing handles misalignment better?
A spherical plain bearing is built to articulate between matching spherical surfaces, so misalignment is part of its normal function within the permitted angle. A standard deep groove ball bearing is relatively rigid and tolerates only limited misalignment. A self-aligning ball bearing is a separate rolling-bearing design made to accommodate angular misalignment.
Which bearing carries more load?
There is no universal winner. Capacity depends on bearing type, size, material, contact geometry, load direction, motion, speed, lubrication and the manufacturer's rating method. Compare calculated life or permissible operating range for the exact candidates, not two catalogue numbers from different bearing families.
Can I replace a ball bearing with a spherical plain bearing of the same bore?
Not without redesign checks. The two bearings can differ in outside diameter, width, shoulders, fits, clearance, friction, speed capability, lubrication, sealing and load response. Review the motion and surrounding parts first, then verify the exact bearing drawing and calculation.
Sources checked
- Dongzhou radial spherical plain bearing range, its four linked product-family pages, and the Dongzhou company profile.
- SKF Spherical Plain Bearings and Rod Ends catalogue, official design, motion and maintenance guidance.
- SKF deep groove ball bearing guidance, official rolling-bearing characteristics.
- SKF Rolling Bearings catalogue, official distinction between rigid and self-aligning bearing types.
- SKF: How to understand ISO 15243, false brinelling and fretting under small movement or vibration.
- Schaeffler Spherical Plain Bearings, Plain Bushes, Rod Ends, official load, sliding velocity and life-calculation framework.
