If you've ever taken apart a pump, an electric motor, or a piece of heavy industrial equipment, you've almost certainly encountered a sleeve bearing — even if you didn't know what to call it.
It's one of the oldest bearing technologies in engineering, yet it's still specified every day in applications that range from automotive crankshafts to wind turbine yaw drives.
Pick the wrong type or material and it fails fast. Pick the right one and it may outlast everything around it.
What Is a Sleeve Bearing?
A sleeve bearing — also called a plain bearing, journal bearing, or bushing — is a cylindrical component that supports a rotating or sliding shaft and reduces friction between moving surfaces.
Unlike ball bearings or roller bearings, a sleeve bearing has no rolling elements whatsoever.
Instead, it relies on a thin film of lubricant (oil, grease, or a self-lubricating material integrated into the bearing itself) to separate the shaft from the bearing surface.
The structure is simple: a hollow cylinder, machined to tight dimensional tolerances, pressed into a housing bore. The shaft rotates or slides inside it. No balls, no cages, no raceways — just a precision-fitted sleeve and the physics of lubrication doing the work.
That simplicity drives the core trade-off: sleeve bearings are compact, quiet, and cost-effective, but their performance depends heavily on operating conditions and material selection in ways that rolling-element bearings do not.
How Does a Sleeve Bearing Work?
The mechanics come down to one concept: lubrication regime.
Depending on load, speed, and lubricant viscosity, a sleeve bearing operates in one of three modes — and knowing which mode applies to your application determines almost every subsequent design decision.
Fig. 1 — At rest, the shaft rests on the bearing surface (metal contact, μ = 0.10–0.20). Under sufficient speed, shaft rotation drags lubricant into a converging wedge, building hydrodynamic pressure that lifts the shaft off the bore entirely. Friction drops to μ ≈ 0.001 with no metal contact.[1]
Hydrodynamic (Full-Film) Lubrication
This is the preferred operating state for oil-lubricated sleeve bearings.
As the shaft rotates, it drags lubricant into the converging wedge-shaped gap between the shaft and the bearing bore, generating hydrodynamic pressure that lifts the shaft off the bearing surface entirely.
Metal never contacts metal.
In full-film conditions, friction coefficients can drop as low as 0.001 — on par with a precision ball bearing, and better than most roller bearings under comparable loads.[1]
Since there's no contact, wear is essentially nil.
The practical catch: you need sufficient shaft speed and appropriate lubricant viscosity to sustain the film.
Hydrodynamic conditions cannot be maintained at startup or shutdown, which is why material selection still matters even in bearings designed for full-film operation.
Boundary Lubrication
When speed is too low, load too high, or the lubricant film breaks down, the bearing enters boundary lubrication.
Surface asperities make intermittent contact, friction rises, and wear becomes a function of the bearing material's properties rather than the lubricant's.
This is the steady-state condition for many slow-oscillating and heavily loaded applications — think construction machinery pivot pins or dam gate trunnions.
Self-lubricating materials (graphite-bronze, PTFE composite) are specifically engineered to perform here.
Mixed-Film Lubrication
A transitional state between full-film and boundary. Part of the load is carried by the fluid film, part by occasional asperity contact.
Friction and wear fall between the other two regimes.
Most bearings pass through mixed-film conditions during startup and shutdown, even when they operate hydrodynamically at steady state.
Fig. 2 — The Stribeck curve: friction is highest during boundary lubrication (startup, slow oscillation), falls through the mixed-film regime, and reaches a minimum at full hydrodynamic film. Very high speeds cause a slight rise due to viscous drag losses.
These three regimes explain the physics of how a sleeve bearing separates the shaft from the bore — but they don't tell you when to actually add oil or grease, or whether you should at all. For maintenance intervals, grease selection by material, and which bearing types should never be greased, see our sleeve bearing lubrication guide.
Types of Sleeve Bearings
Sleeve bearings break down along two dimensions: geometry (which load directions the bearing handles) and lubrication method (whether the bearing needs external oil or carries its own).
The three geometries are cylindrical, flanged, and thrust — each available in oil-embedded and dry-running variants, plus general-purpose and corrosion-resistant grades.
Together they cover the full product range.
Fig. 3 — The three sleeve bearing geometries. Each is available in oil-embedded and dry-running variants; thrust washers are typically paired with a cylindrical sleeve in the same assembly.
Cylindrical (Plain) Sleeve Bearings
Straight cylinder, uniform ID and OD. Handles purely radial loads. The most common sleeve bearing geometry in general industrial machinery — pumps, fans, motors, conveyors. Press-fits directly into a housing bore.
Oil-Embedded Sleeve Bearings
Made from sintered bronze compacted and vacuum-impregnated with mineral oil — the oil bleeds to the surface under load and heat, providing continuous lubrication with no external supply.
The standard choice for light-to-moderate radial loads at moderate speeds where routine re-lubrication isn't practical.
Rated to approximately 80–120°C. High-load, ultra-low-friction, vibration-damping, and panel-mount variants are available within this category.
Food Industry Oil-Embedded Sleeve Bearings
Same sintered bronze construction as standard oil-embedded bearings, but manufactured with NSF-certified, food-grade lubricants and non-toxic materials that comply with FDA requirements.
Specified wherever incidental lubricant contact with food or beverage products is possible — conveyor drives, filling equipment, packaging machinery.
High-load food-industry variants are available for heavier-duty applications in the same regulated environments.
Dry-Running Sleeve Bearings
Self-lubricating composite or polymer bearings that require zero external oil or grease.
The material itself — typically PTFE composite, engineering polymer, or graphite-bronze — provides the lubricating function directly at the sliding interface.
Wider temperature range than sintered bronze (PTFE composite: −200°C to +260°C), and available in high-load, high-temperature, ultra-low-friction, chemical-resistant, water-resistant, harsh-environment, and panel-mount variants to match specific operating conditions.
Multipurpose & Corrosion-Resistant Sleeve Bearings
General-purpose cylindrical sleeve bearings designed to perform reliably across a broad range of loads, speeds, and lubrication conditions without being optimized for any single extreme.
Corrosion-resistant grades are manufactured from stainless steel, aluminum bronze, or corrosion-resistant polymer composites for wet, marine, or chemically aggressive environments where standard bronze would corrode.
Groove versions — with an integrated circumferential or axial channel — improve lubricant distribution and retention in applications where periodic re-lubrication is part of the maintenance routine.
Flanged Sleeve Bearings
A cylindrical bearing with a collar at one end extending radially outward. The flange provides a positive locating surface during assembly and resists axial shaft migration — so you get radial and one-direction axial support in a single part. Common in gearboxes, conveyor drives, and any application where the shaft must be positively located axially. For ISO 4379 dimensions, PV limits by material, and a full 7-step selection process, see our dedicated Flanged Sleeve Bearings guide.
Oil-Embedded Flanged Sleeve Bearings
Flanged geometry with sintered bronze oil-impregnated construction — self-lubricating under normal conditions, no external oil required. The flange face handles axial positioning and light thrust loads while the bore carries the radial load. High-load, ultra-low-friction, and certified variants are available, as well as food-industry grades with NSF-compliant lubricants for regulated processing environments.
Dry-Running Flanged Sleeve Bearings
Lubrication-free flanged bearings in composite or polymer materials, covering the widest range of specialty variants in the flanged category. Self-aligning designs automatically compensate for shaft misalignment up to a specified angular range — useful where housing alignment cannot be guaranteed. Easy-install snap-in designs cut assembly time on the production line. High-temperature grades handle thermally demanding environments; food-industry, chemical-resistant, and water-resistant grades address specific contamination or corrosion requirements. High-speed self-aligning variants are also available for faster rotating applications.
Multipurpose & Corrosion-Resistant Flanged Sleeve Bearings
Versatile flanged bearings for general-purpose duty across a broad range of loads and speeds, without a specific material optimization. Corrosion-resistant flanged versions in stainless steel or specialized alloy are the right call for marine, chemical, or outdoor environments where standard materials would deteriorate. Certified variants are backed by material and dimensional certification for applications where traceability is required.
Thrust Bearings (Washers)
Flat ring geometry — no bore, pure face contact — designed to carry axial loads that a cylindrical sleeve bearing cannot. In most assemblies, a thrust washer works alongside a cylindrical sleeve: the sleeve handles radial load, the thrust washer handles the axial component. Available in oil-embedded and dry-running variants across the same specialty grades as the cylindrical and flanged ranges.
Oil-Embedded Thrust Bearings
Sintered bronze thrust washers with oil permanently embedded in the porous matrix, providing self-lubrication at the bearing face without an external oil supply.
Suited to moderate axial loads at moderate speeds in assemblies where re-lubrication access is limited. High-load, ultra-low-friction, and food-industry grades are available within this category for more demanding or regulated applications.
Dry-Running Thrust Bearings
Completely lubrication-free thrust washers in composite or polymer materials.
The dry-running range covers the broadest set of environmental conditions:
light-duty grades for low-speed, low-load axial positioning;
high-load grades for heavy axial forces;
high-temperature grades for thermally demanding assemblies;
ultra-low-friction grades where minimizing axial drag matters;
and food-industry, water-resistant, and chemical-resistant grades for specialized environments.
Multipurpose & Corrosion-Resistant Thrust Bearings
General-purpose thrust washers for standard axial load applications across a wide range of speeds and lubrication conditions.
Corrosion-resistant thrust bearings in stainless steel, aluminum bronze, or resistant polymer handle aggressive environments — marine shaft assemblies, chemical processing equipment, or outdoor installations — where standard bronze thrust washers would corrode or degrade prematurely.
Sleeve Bearing Materials
Material selection is the highest-leverage decision in sleeve bearing specification — it determines lubrication mode, load limits, temperature ceiling, and maintenance requirements all at once.
Two bearings that look identical can have completely different service lives depending solely on what they're made of.
●●●●● = very high load capacity · ●○○○○ = light load only · Friction coefficients shown for boundary / dry-running conditions. Hydrodynamically lubricated bronze achieves μ ≈ 0.001 in full-film operation.
Fig. 4 — Material comparison. Hydrodynamically lubricated bronze achieves μ ≈ 0.001 in full-film operation.[1] Babbitt temperature limits: tin-base (Sn) 100–110°C, lead-base (Pb) 120–130°C.[2]
Bronze Alloys
Bronze has been the default sleeve bearing material for good reason: it combines respectable compressive strength, excellent wear resistance, and reliable performance across both hydrodynamic and boundary lubrication conditions.
Three alloy families dominate:
Tin bronze (C90500, C90700): The workhorse. Good corrosion resistance, widely stocked, used in pumps, motors, and general industrial machinery.
Lead bronze: Higher lead content improves embeddability — small contaminant particles embed into the soft lead phase rather than scoring the shaft. Standard for engine crankshaft and connecting-rod bearings.
Aluminum bronze: Significantly higher strength and corrosion resistance. The right choice for marine environments, chemical processing, and saltwater exposure.
Babbitt (White Metal)
A soft tin- or lead-based alloy used as a lining material in large journal bearings. Babbitt's defining properties are conformability and embeddability.
The trade-off is lower load capacity and a relatively low temperature ceiling — tin-based babbitt begins to soften around 100–110°C; lead-based grades extend this to approximately 120–130°C.
PTFE Composite (DU-Type)
The most common self-lubricating bearing construction: a steel backing, a sintered bronze interlayer, and a PTFE sliding surface, typically 0.01–0.03 mm thick.
Typical dry-running friction coefficient: μ = 0.03–0.15.[2] Operating temperature range: −200°C to +260°C continuous.
Sintered Bronze (Oil-Impregnated)
Manufactured by compacting bronze powder and sintering it to create a porous matrix, then vacuum-impregnating the pores with mineral oil.
Per ASTM B438, oil content is typically 15–25% by volume. Works well at light-to-moderate loads and moderate speeds.
Not suited to high loads or high temperatures (rated to approximately 80–120°C).
Engineering Plastics (POM, Nylon, PEEK)
Polyoxymethylene (POM/Delrin) and polyamide (nylon/PA) offer chemical resistance, zero corrosion, and immunity to many lubricants — making them logical choices for food processing and medical equipment.
PEEK handles higher temperatures, up to approximately 250°C continuous.
Graphite-Bronze
Bronze with distributed graphite plugs across the bearing surface.
During operation, graphite is transferred to the shaft, creating a solid lubricant film. Friction coefficient in working conditions: μ = 0.10–0.20, higher than PTFE composite but with better load capacity at elevated temperatures.
Key Performance Parameters
PV Value (Pressure × Velocity)
The fundamental performance limit for self-lubricating sleeve bearings.
P is the projected bearing pressure (load ÷ bore diameter × length, in MPa), V is the shaft surface velocity (in m/s).
Reference values: sintered bronze (SAE 841) ≈ 1.75–2.5 MPa·m/s; PTFE composite (DU-type) dry PV limit ≈ 0.04–0.10 MPa·m/s.
Consult material data sheets for your actual conditions.
Friction Coefficient (μ)
Ranges from ~0.001 for hydrodynamically lubricated bronze in full-film conditions, to 0.03–0.15 for PTFE composite running dry, to 0.10–0.20 for graphite-bronze.
The friction coefficient is not a fixed property — it varies with load, speed, temperature, and lubrication state.
Operating Temperature
Sintered bronze with mineral oil: typically rated to 80–120°C.
PTFE composite: −200°C to +260°C.
Graphite-bronze: up to 300°C+ in some grades. PEEK-based plastics: to approximately 250°C continuous.
Sleeve Bearings vs. Ball Bearings
This comparison comes up in almost every bearing selection discussion. Neither is universally better — each dominates in specific conditions. For a deeper side-by-side breakdown of load ratings, speed limits, and cost, see our full Sleeve Bearing vs Ball Bearing comparison guide.
Factor | Sleeve Bearings | Ball / Roller Bearings |
|---|---|---|
Unit cost | Lower | Higher |
Noise at low speed | Quieter | Can be noisier |
Radial load capacity | High | Good |
Axial load capacity | Good (flanged + thrust washer) | Good |
High-speed performance | Limited | Better suited |
Radial space required | More compact | Requires more space |
Maintenance (self-lubricating) | Minimal / none | Periodic lubrication needed |
Shock load tolerance | Moderate | Better |
Life under ideal conditions | Potentially very long (full-film) | Fatigue-limited |
Contamination sensitivity | Higher (film disruption) | Better sealed options |
The practical rule: where speed is low, loads are high, space is tight, or maintenance access is limited, sleeve bearings typically win. Where speed is high, precision is critical, or shock loads are severe, rolling-element bearings are usually the better choice.
Applications by Industry
Automotive
Every internal combustion engine contains sleeve bearings.
Crankshaft main bearings and connecting-rod bearings are trimetal or bimetal journal bearings — steel-backed, copper-lead or aluminum alloy lined — operating under continuous high load and heat.
As EV architectures evolve, sleeve bearings are appearing in new contexts: motor shaft support, gearbox pivots, and battery cooling pump assemblies.
Industrial Machinery
Pumps, compressors, fans, electric motors, and conveyor drives are the highest-volume applications for sleeve bearings globally.
Their durability under continuous duty cycles, combined with low maintenance requirements, makes them the default choice for equipment that runs 24/7 with limited downtime.
Explore our range of sleeve bearings for industrial machinery.
Construction and Agricultural Equipment
Excavator arm pins, bulldozer track links, agricultural machinery pivot joints — anywhere you have high static loads, oscillating or slow rotary motion, and likely contamination, graphite-bronze or bimetal composite sleeve bearings are standard.
Marine
Stern tube bearings supporting propeller shafts must carry large radial loads while running water-lubricated — using seawater as the lubricant — and tolerating shaft misalignment and marine fouling.
Rubber-lined, polymer composite, and cutlass-type bearings are the common material choices here.
Aerospace and Defense
Control surface actuator bushings, landing gear trunnion bearings, and certain engine accessory drive bearings use high-performance composite sleeve bearings.
PTFE composite and PEEK-based bearings are common.
Energy — Wind Turbines
Wind turbine pitch control systems and yaw drives increasingly use large plain bearings.
Unlike rolling-element alternatives, plain bearings handle the slow, heavily loaded oscillating motion of these systems without the fatigue limitations that limit rolling-element life in this specific application.
Food Processing and Medical Devices
Self-lubricating polymer and PTFE composite sleeve bearings are essential wherever lubricant contamination would compromise product safety or sterility.
FDA-compliant materials, resistance to washdown chemicals, and corrosion immunity drive specification here. Both food-industry oil-embedded and dry-running grades with NSF certification are available for these applications.
How to Select the Right Sleeve Bearing
Work through these six factors in sequence. Skipping any of them is how premature failures happen.
Fig. 5 — Six-step selection process. Follow in sequence; each step constrains the next.
Define the load
Radial only, axial only, or combined? Calculate the projected bearing pressure: P = applied load ÷ (bore diameter × bearing length). This determines whether you need a cylindrical, flanged, or thrust washer configuration.
Establish the shaft speed
Surface velocity (V = π × shaft diameter × RPM) combined with P gives you the PV value — the primary material selection screen for self-lubricating bearings.
Determine the lubrication mode
Can you supply continuous oil? If so, hydrodynamically lubricated bronze is viable. If not — self-lubricating materials (sintered bronze for light loads, PTFE composite or graphite-bronze for heavier or higher-temperature service) are the practical path.
Identify the operating environment
Temperature extremes, exposure to moisture, chemicals, abrasive particles, and the presence of shock or vibratory loads all constrain material and design choices.
Consider shaft hardness and surface finish
Bronze and babbitt require shafts hardened to at least HRC 45–50 and finished to Ra 0.4–0.8 μm for best results. PTFE composites are more tolerant of shaft surface condition.
Choose geometry
Plain cylindrical for purely radial loads; flanged where axial positioning is needed; thrust washer where axial loads must be handled alongside a radial sleeve.
When in doubt, bring your operating parameters to the bearing supplier's engineering team. The conversation costs nothing; a misspecified bearing costs production time and replacement labor.
Common Failure Modes and Root Causes
Even correctly specified sleeve bearings fail when operating conditions drift. Knowing the failure modes helps with both root-cause diagnosis and preventive specification.
| Abrasive WearContaminant particles in the lubricant score and abrade the bearing surface. Fix: improve filtration, use materials with better embeddability (lead bronze, babbitt), or switch to sealed housing configurations. | SeizureMetal-to-metal contact from lubricant film collapse, inadequate clearance, or overloading. Often initiated at startup before hydrodynamic conditions establish. In self-lubricating bearings, indicates operation beyond the PV limit. |
| Fatigue CrackingCyclic loading causes subsurface cracks and surface pitting, particularly in babbitt linings under variable or shock loads. Indicates a load rating problem or unaccounted shock loads in the specification. | CorrosionEspecially in wet, marine, or chemically aggressive environments. Material selection is the primary defense: stainless steel, aluminum bronze, or PTFE composites depending on the chemical environment. |
| FrettingMicro-motion between the bearing OD and housing bore causes wear and loosens the press fit over time. Addressed through correct interference fit specifications and appropriate housing material selection. | OverheatingInadequate oil supply or excessive load breaks down the lubricant film; sustained high temp depletes self-lubricating reservoirs. Either path leads to seizure — catch it early through temperature monitoring. |
FAQ
What is the difference between a sleeve bearing and a bushing?
In everyday engineering usage, the terms are interchangeable — both refer to a cylindrical plain bearing that supports a shaft without rolling elements.
Technically, "bushing" sometimes implies a shorter, thin-walled press-fit insert used as a replaceable liner, while "sleeve bearing" can imply a longer, more substantial component for continuous heavy-load service.
In practice, most engineers and suppliers use both terms for the same product category. For bushing-specific materials and a dedicated selection framework, see our guide to bushing types and materials.
Do sleeve bearings need lubrication?
It depends on the type. Oil-lubricated plain bearings (bronze in hydrodynamic applications) require a continuous oil supply.
Grease-lubricated bearings need periodic re-greasing. Self-lubricating types — sintered bronze, graphite-bronze,
PTFE composite — carry their own lubricant and require no external lubrication under normal operating conditions.
How long do sleeve bearings last?
In full-film hydrodynamic conditions with clean lubricant, a properly specified sleeve bearing has no inherent wear mechanism — service life is limited by corrosion, contamination, or changes in operating conditions rather than fatigue.
Sintered bronze bearings in light-duty applications are typically rated for tens of thousands of operating hours.
PTFE composite bearings in automotive suspension applications are typically designed for the life of the vehicle.
What is the difference between a sleeve bearing and a ball bearing?
A sleeve bearing has no rolling elements — a shaft slides inside a cylindrical bore on a lubrication film or self-lubricating material.
A ball bearing uses small steel balls rolling between inner and outer rings to minimize friction.
Sleeve bearings are generally quieter at low speeds, more compact radially, lower in cost, and better suited to high radial loads with slow oscillating motion.
Ball bearings handle higher speeds, axial loads in both directions, and shock loads more effectively.
Can sleeve bearings handle both radial and axial loads?
A plain cylindrical sleeve bearing handles only radial loads.
A flanged sleeve bearing handles combined radial and axial loads through the flange face.
Where both load directions must be managed with a cylindrical bearing, a separate thrust washer is added alongside it to handle the axial component.
What causes a sleeve bearing to fail?
The most common causes are inadequate lubrication (film breakdown leading to metal contact), contaminant ingress (abrasive particles scoring the surface), operating outside the design load or speed envelope (exceeding PV limits in self-lubricating types), and incorrect installation clearance — too tight causes overheating, too loose causes vibration and uneven load distribution.
Sources
Copper Development Association — Selecting Bronze Bearing Materials: View technical reference
GGB Bearings — GGB-DB Self-Lubricating Bronze Bearing Solutions: Download GGB-DB catalog PDF
ASTM B438 — Standard Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated): Visit ASTM International
Wikipedia — Plain bearing: Read on Wikipedia
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