Caster Bearing Types Explained: Plain, Roller, Ball, and Precision
Caster bearing type governs rolling resistance, load capacity, serviceability, and service life. Five bearing configurations dominate industrial casters: plain bore, Delrin bushing, roller bearing, single or dual ball bearing, and sealed precision ball. Each has a defined load envelope, rolling drag coefficient, and maintenance profile. Wrong bearing choice at RFQ drives premature failure, high push force, and elevated 5-year TCO. This spec explains each type and the selection rules that keep fleets rolling.
In this guide
Quick Answer: Bearing by Duty Class
Plain bore for institutional and light duty. Delrin for chemical or sanitary light duty. Roller bearing for high static capacity with occasional rolling. Ball bearing for general industrial. Sealed precision ball for continuous, powered, AGV, and any application where push force or serviceability matters.
- Plain bore: cheap, simple, loud. Institutional under 500 lb.
- Delrin bushing: chemical-resistant, low-friction bushing. Washdown and sanitary.
- Roller bearing: highest static capacity. Line contact between roller and race.
- Ball bearing (single or dual): industrial default. Point contact.
- Sealed precision ball: lowest push force, highest service life, lowest TCO.
Engineer tip: Bearing upgrade is almost always cheaper than rig upgrade. A sealed precision bearing in a standard rig outperforms a plain bore in a premium rig on every TCO metric.
Five Bearing Types Explained
The five bearing types used in industrial casters have distinct construction, cost, and performance signatures.
- Plain bore: steel or brass bushing in hub. No rolling elements. Cheapest. Highest friction. Runs on hub grease.
- Delrin (acetal) bushing: engineered polymer bushing. Self-lubricating. Excellent chemical resistance. Moderate load.
- Roller bearing: cylindrical rollers in hardened race. High static capacity, line contact. Typically greasable.
- Ball bearing (single or dual row): hardened balls in machined race. Point contact. Wide load and speed range.
- Sealed precision ball (ABEC-1 and above): factory-sealed ball bearing with machined inner/outer race. Lifetime grease. Lowest drag.
Data point: Across 320 industrial caster push-force measurements (2023-2026), sealed precision ball bearings averaged 3.1 lb per 1,000 lb of cart weight. Standard ball bearings averaged 4.4 lb. Roller bearings averaged 5.2 lb. Plain bore averaged 6.8 lb. Source: CasterHQ push-force panel, Q1 2026.
Rolling Drag Coefficient by Type
Rolling drag coefficient is the single most consequential bearing metric for push-force ergonomics. Lower is better. Sealed precision ball bearings typically cut push force 40-55% versus plain bore on the same cart.
| Bearing Type | Typical Drag Coefficient | Push Force per 1,000 lb |
|---|---|---|
| Plain bore (bushing) | 0.012-0.018 | 6-8 lb |
| Delrin bushing | 0.008-0.014 | 4-6 lb |
| Roller bearing (greased) | 0.010-0.016 | 5-7 lb |
| Ball bearing (standard) | 0.006-0.010 | 3-5 lb |
| Sealed precision ball (ABEC-1) | 0.004-0.007 | 2-4 lb |
| Sealed precision ball (ABEC-3+) | 0.003-0.005 | 2-3 lb |
Load Capacity Envelopes
Static load capacity varies by bearing type more than it does by rig construction. Roller bearings dominate in high-static, low-rotation applications. Sealed precision ball bearings dominate in continuous rolling.
- Plain bore: 100-1,000 lb per caster typical.
- Delrin bushing: 100-800 lb per caster typical.
- Roller bearing: 500-10,000+ lb per caster typical.
- Ball bearing: 200-3,000 lb per caster typical.
- Sealed precision ball: 200-4,000 lb per caster typical; specialty to 6,000+.
Service Intervals by Bearing Type
Service cadence varies dramatically by bearing type. Plain bore and greasable ball bearings require quarterly to annual service. Sealed precision bearings require visual inspection only.
- Plain bore: quarterly grease, annual bushing check.
- Delrin bushing: annual visual; replace at wear.
- Roller bearing (greasable): quarterly grease, annual repack.
- Ball bearing (greasable): semi-annual grease, annual repack.
- Sealed precision ball: annual visual inspection; no repack.
| Bearing Type | Grease Interval | Repack Interval | Replacement Trigger |
|---|---|---|---|
| Plain bore | Quarterly | N/A | Audible drag or wobble |
| Delrin bushing | None | N/A | Visible wear or deformation |
| Roller (greasable) | Quarterly | Annual | Noise or heat |
| Ball (greasable) | Semi-annual | Annual | Noise or drag spike |
| Sealed precision ball | None | None | Noise or seal breach |
Selection Rules by Application
Pick bearing type by duty and environment, not by price sheet. Five rules cover most industrial and institutional selections.
- Hospital, hotel, office: sealed precision ball for quiet and low-maintenance.
- Light industrial (workbench, tool cart): standard ball bearing, greasable.
- Heavy stationary load (die rack): roller bearing.
- Continuous rolling or tow: sealed precision ball.
- AGV / powered / automation: sealed precision ball with integrated seal and NSF H1 grease if food or pharma.
Engineer tip: Push force is a safety metric, not just a comfort metric. Liberty Mutual and NIOSH data both show injury risk rises sharply above 50 lb push force. Bearing type moves push force by 2-4 lb per 1,000 lb of cart. That math matters at scale.
Bearing Spec Checklist
Use this checklist at RFQ. Any continuous-rolling application or any cart with a push-force ergonomic constraint should trigger all seven questions.
- What is the static load per caster at rest?
- What is the duty cycle in rolling hours per week?
- Is push force ergonomically constrained (under 50 lb per operator)?
- Is the environment wet, chemical, or food-contact?
- Is PM service scheduled and enforced?
- What is the target service life (1 year, 3 years, 5 years)?
- Is the application towed, powered, or AGV?
Key takeaways
- Five bearing types dominate: plain bore, Delrin, roller, ball, sealed precision ball.
- Sealed precision ball cuts push force 40-55% vs plain bore on the same cart.
- Roller bearings dominate in high-static, low-rotation applications.
- Sealed precision ball is required for AGV, powered, and any ergonomic-critical duty.
- Bearing upgrade is almost always cheaper than rig upgrade on 5-year TCO.
Frequently asked questions
What is the difference between a plain bore and a ball bearing caster?
Plain bore uses a cylindrical bushing in the hub with no rolling elements. Ball bearings use hardened balls in a machined race. Ball bearings run cooler, quieter, and with 30-50% less push force than plain bore at the same load.
Are sealed precision bearings worth the cost?
Yes for any continuous-rolling, powered, or ergonomic-critical application. Sealed precision bearings cut push force 40-55%, eliminate repack labor, and extend service life 2-4x versus greasable equivalents. 5-year TCO almost always favors sealed precision.
When should I spec a roller bearing over a ball bearing?
When the application is high static load with occasional rolling. Roller bearings carry more static capacity per unit size. Ball bearings carry less static but roll more efficiently. Die racks lean roller. Utility carts lean ball.
What is a Delrin bushing?
Delrin (acetal resin) is an engineering polymer used as a self-lubricating bushing. It handles mild chemical environments, washdown, and light duty without grease. Load capacity is lower than steel ball bearings but it needs no maintenance.
How often should caster bearings be serviced?
Plain bore and greasable ball or roller bearings need quarterly to annual grease and annual repack depending on duty. Sealed precision bearings need only annual visual inspection. Maintenance-free (sealed) bearings eliminate PM labor entirely.
Does bearing type affect caster noise?
Yes. Sealed precision bearings run the quietest. Plain bore and roller bearings generate broadband rumble. See the noise-and-vibration spec for dB-level comparisons.
Pick the Right Bearing for Load, Duty, and Push Force
Share your cart weight, duty cycle, and ergonomic constraints. We return a bearing-specific spec with push-force math.
References & Standards Cited
- ABMA Bearing Standards (ABEC precision ratings)
- ISO 22878 Castors and Wheels Terminology and Test Methods
- SMRP Body of Knowledge, bearing failure modes
- Liberty Mutual Snook tables (push-force ergonomics)
- NIOSH push-force guidelines
- CasterHQ push-force panel data, 2023-2026
