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6811 Bearing 55x72x9mm | 9.1kN Load | RHD Bearings

Fifty-five millimeter bore that's proof that good things come to those who optimize their footprint.

Meet the 6811: With 927kg (9.1kN) of engineering excellence and 55mm precision, this bearing delivers the perfect blend of personality and performance for your critical applications. The most widely used bearing in electronics, small motors, and precision instruments.

55mm
Bore Diameter
72mm
Outer Diameter
9mm
Width
9.1 kN
Load Rating
927 Kg
Load Capacity
0.07 Kg
Weight
Technical Specifications Applications 📞 Call +91-9702081858
6811 Bearing 55×72×9mm - RHD Bearings

6811 BEARING SPECIFICATIONS

Precision-engineered for reliability and performance

🔍 Common Search Terms

55mm bore bearing compact bearing 72mm outer diameter high speed small bearing 9.1kN load capacity bearing precision miniature bearing 6811 bearing specifications

📏Dimensions

d - ID (Bore Diameter)
55mm
D - OD (Outer Diameter)
72mm
B - Width
9mm
d₁ - Shoulder Diameter
≈60.5mm
D₂ - Recess Diameter
≈0.0mm
r₁,₂ - Chamfer Radius
min. 0.3mm
6811 Bearing: 55 × 72 × 9mm

Cross-Sectional View

6811 Bearing Cross-Sectional View

⚡Load Ratings

Dynamic Load (Cr) 9.1kN
Static Load (Cor) 8.4kN
Load Capacity (kN) 9.1kN
Load Capacity (kg) 927kg

💡What This Means

Dynamic Load (9.1kN): Maximum force while rotating. Exceeding this causes rapid wear and failure within hours.
Static Load (8.4kN): Maximum force when stationary. Use 80% for safety.
Calculate Your Load: Measure shaft forces, belt tensions, or gear loads. Include shock/vibration factors.
Failure Warning: Overloading causes bearing raceways to crack and balls to flatten permanently.

🔄Speed Limits

Grease Lubrication 7500 RPM
Oil Lubrication 9000 RPM
RHD Z2V2 Bearings 1400 RPM
RHD Z3V3 Bearings 2880 RPM
RHD Z4V4 Bearings 6000+ RPM

💡What This Means

Grease Limit (7500 RPM): Heat generation increases exponentially above this. Grease breaks down, causing seizure.
Oil Advantage (9000 RPM): Better heat dissipation allows higher speed. Required for high-speed spindles.
Safe Operating Speed: Use 90% of limit (6750 RPM) for maximum L10 life of 10,000+ hours.
Failure Mode: Exceeding speed causes cage failure, ball skidding, and catastrophic overheating within minutes.

🔧Material & Quality

Steel Grade SAE52100
Ball Grade G10
Carbon Content 0.95-1.05%
Chromium Content 1.40-1.65%
ISO Standard 15:2011 Compliant

💡What This Means

SAE52100 Chrome Steel: Premium bearing steel - harder than tool steel
G10 Balls: Ultra-precision balls with ±0.25µm tolerance
High Carbon: Superior hardness and wear resistance
Chromium: Adds corrosion resistance and toughness
ISO Standard: Fits any 6811 application worldwide

📊Vibration Classes

V2 Grade
Low: 210 μm/s
Med: 180 μm/s
High: 180 μm/s
V3 Grade
Low: 125 μm/s
Med: 110 μm/s
High: 110 μm/s
V4 Grade
Low: 95 μm/s
Med: 70 μm/s
High: 70 μm/s

💡What This Means

V2 Grade: Standard grade - good for general applications
V3 Grade: Low vibration - like a smooth car engine
V4 Grade: Ultra-smooth - for precision instruments
Frequency Bands: Measured across different rotation speeds

🔇Noise Levels

Z2 Grade < 53 dB
Z3 Grade < 50 dB
Z4 Grade (Quiet) < 47 dB
Application Precision Equipment

💡What This Means

Z2 Grade: Quiet as a library - good for most applications
Z3 Grade: Very quiet - like a whisper (40 dB = normal whisper)
Z4 Grade: Ultra-quiet - perfect for bedroom fans, medical equipment
Application: Ideal for sensitive environments

⚙️Internal Clearance

C2 (Tight) 1-15 μm
C0 (Normal) 8-28 μm
C3 (Loose) 23-43 μm
C4 (High Temp) 38-61 μm
C5 (Extra High Temp) 55-90 μm

💡What This Means

C2 (Tight): Precision applications - less play, more accurate
C0 (Normal): Standard choice - works for most applications
C3 (Loose): Better for hot environments - allows thermal expansion
C4 (Exta Loose): Hot or tight-fit setups — extra room for thermal expansion.
C5 (Max Loose): Extreme heat/tight fits or near-limit speeds — maximum expansion allowance

SEAL OPTIONS

Choose the right protection for your application

6811-ZZ

Most Popular

Double metal shields

Speed Factor: 0.9 (6750 RPM)
Protection: Dust protection
Lubrication: Sealed for life

When to Use 6811-ZZ

Best For: Electronics, small motors, skateboards, general machinery
Conditions: Dry environments, moderate dust, precision applications
Achieves: Excellent balance of speed and protection for most applications
Avoid When: Heavy water exposure, chemical environments, food processing

6811-2RS

Protected

Double rubber seals

Speed Factor: 0.7 (5250 RPM)
Protection: Moisture and dust
Lubrication: Sealed for life

When to Use 6811-2RS

Best For: Outdoor applications, appliances, automotive systems, dirty environments
Conditions: Moisture, dust, contamination, washdown areas, food processing
Achieves: Maximum protection and zero maintenance requirements
Trade-off: Lower speed limit but superior environmental protection

6811

High Speed

Open bearing, no seals

Speed Factor: 1.0 (7500 RPM)
Protection: None
Lubrication: External required

6811-Z

Balanced

Single metal shield

Speed Factor: 0.95 (7125 RPM)
Protection: Light dust protection
Lubrication: Pre-greased

6811-RS

Protected

Single rubber seal

Speed Factor: 0.8 (6000 RPM)
Protection: Moisture and dust
Lubrication: Pre-greased, sealed

APPLICATIONS

Precision performance across industries

Pump Drives

  • Centrifugal pump shafts
  • Hydraulic pump drives
  • Water transfer pumps
  • Oil pump shafts
  • Industrial fluid pumps
  • Chemical dosing pumps
  • Food grade pump shafts
  • Cooling system pump drives

Key Requirements: 55mm shaft with 9.10kN (≈927kg) dynamic load, 6,700 RPM grease lubrication, 72×9mm for pump drives

Heavy Machinery

  • Material handling equipment
  • Mining haul trucks
  • Construction vehicle pivots
  • Industrial press bearings
  • Aggregate crusher shafts
  • Farm equipment joints
  • Bulk material movers
  • Industrial mixers

Key Requirements: Precision 55mm bore with 8.40kN (≈857kg) static load

Conveyor Rollers

  • Warehouse conveyor rollers
  • Sortation system pulleys
  • Assembly line conveyors
  • Mining belt rollers
  • Material transfer rollers
  • Bulk goods movers
  • Packaging conveyor spindles
  • Log transport rollers

Key Requirements: 55mm bore, 9mm width for high-load conveyor systems

Compatible Models & Shaft Requirements

Find bearings with the same bore size and ensure proper shaft preparation

🔄Related Models

6911 (55×80×13mm) 16011 (55×90×11mm) 6011 (55×90×18mm) 6211 (55×100×21mm) 62211 (55×100×25mm) 62311 (55×120×43mm) 6311 (55×120×29mm)

🔧Shaft Requirements

Nominal Diameter 55.000mm
Tolerance Grade h6 (54.981-55.000mm)
Surface Finish Ra 0.8μm max
Runout Tolerance 0.013mm max

🎯Application-Specific Options

High Temperature: C3 clearance recommended
High Speed: RHD V3 & V4 bearings recommended
Corrosive Environment: SS (Stainless Steel) bearings recommended

Professional Expertise & Standards

Technical insights from 20+ years of bearing engineering and manufacturing excellence

📋ISO Compliance

ISO 15:2011 compliant dimensions ensure interchangeability with global bearing standards and seamless replacement in existing equipment.

🔬Material Science

Gcr15 chrome steel composition optimized for small bearing applications, providing superior hardness, wear resistance, and fatigue life.

⚙️Precision Engineering

C0 clearance standard for most applications, C3 available for high-temperature use. h6 shaft tolerance recommended for optimal performance.

🔧Professional Installation

Professional installation required for maximum 50,000-hour service life. Proper tools and techniques prevent 80% of premature failures.

📊Performance Comparison

Shares the 55mm bore (ID) with 6911, 16011, 6011, so it can be considered where the shaft is fixed at 55mm. The 6811 is rated 9.10kN dynamic / 8.40kN static at 72mm OD — the most compact 55mm-bore option, below the 6911 (15.90kN).

💰Value Engineering

Best value in compact bearing category for 9.1kN performance. Quality bearings last 3-10x longer than cheap alternatives, reducing total cost of ownership.

FREQUENTLY ASKED QUESTIONS

Expert guidance for 6811 bearing applications

Bearing Selection & Replacement ▼

What applications is the 6811 bearing suitable for?

The 6811 bearing is ideal for compact applications requiring high precision, including small motors, fans, precision instruments, and miniature machinery.
Why This Matters
Proper bearing selection ensures optimal performance, longevity, and prevents premature failure in your equipment.
How To Handle It
Consider load requirements (928.2kg (9.1kN) dynamic), speed needs (7,500 RPM), and space constraints (55x72x9mm dimensions).
For high-speed applications, consider oil lubrication for maximum 9,000 RPM capability.

Can I replace a 6811 bearing with a different model?

Yes, but only with bearings having identical dimensions (55x72x9mm) and similar or higher load ratings to maintain performance.
Why This Matters
Incorrect replacement can cause equipment failure, increased wear, and safety hazards.
How To Handle It
Always verify bore diameter (55mm), outer diameter (72mm), and width (9mm) before replacement.
Check load ratings - replacement bearing should have at least 928.2kg (9.1kN) dynamic load capacity.

What's the difference between open, shielded, and sealed 6811 bearings?

Open (6811) offers maximum speed, single shield (6811-Z) provides dust protection, double shield (6811-ZZ) offers better sealing, and sealed versions (6811-RS/2RS) provide moisture protection.
Why This Matters
Seal type affects speed capability, maintenance requirements, and environmental protection.
How To Handle It
Choose based on environment: clean indoor use (open), dusty conditions (shields), or wet/harsh environments (seals).
Sealed bearings reduce maintenance but have lower speed ratings - consider your application's priority.
Installation & Maintenance ▼

What shaft tolerance is recommended for 6811 bearing installation?

h6 tolerance (54.991-55.009mm) is recommended for optimal fit and performance with the 55mm bore.
Why This Matters
Proper shaft tolerance ensures correct interference fit, prevents slippage, and maximizes bearing life.
How To Handle It
Machine shaft to h6 tolerance range and ensure surface finish of Ra 0.8μm maximum.
Use proper installation tools to avoid damaging the bearing during press-fit installation.

How often should 6811 bearings be lubricated?

Open bearings require regular lubrication every 3-6 months, while sealed bearings are lubricated for life and don't require maintenance.
Why This Matters
Proper lubrication prevents wear, reduces friction, and extends bearing service life significantly.
How To Handle It
Use high-quality grease suitable for high-speed applications and follow manufacturer's lubrication intervals.
Monitor bearing temperature and noise - changes may indicate lubrication issues.

What's the maximum operating temperature for 6811 bearings?

Standard 6811 bearings operate up to 120°C, with C3 clearance versions suitable for higher temperatures up to 150°C.
Why This Matters
Exceeding temperature limits causes lubricant breakdown, dimensional changes, and premature failure.
How To Handle It
Monitor operating temperature and consider C3 clearance for high-temperature applications.
Use high-temperature grease for applications above 80°C to maintain proper lubrication.
Troubleshooting & Problem Solving ▼

Why is my 6811 bearing running hot?

Common causes include over-lubrication, insufficient lubrication, misalignment, excessive load, or contamination.
Why This Matters
Overheating leads to lubricant breakdown, dimensional changes, and catastrophic bearing failure.
How To Handle It
Check lubrication levels, verify load capacity (max 928.2kg (9.1kN)), ensure proper alignment, and inspect for contamination.
Use infrared thermometer to monitor bearing temperature - should not exceed 80°C under normal operation.

What causes excessive noise in 6811 bearings?

Noise typically indicates contamination, insufficient lubrication, bearing damage, or improper installation.
Why This Matters
Unusual noise often precedes bearing failure and can indicate serious mechanical issues.
How To Handle It
Inspect for contamination, check lubrication, verify proper installation, and replace if damage is found.
Use stethoscope or vibration analysis to identify noise source and severity.

How do I know when to replace a 6811 bearing?

Replace when you notice excessive play, rough rotation, unusual noise, overheating, or visible damage.
Why This Matters
Delayed replacement can cause equipment damage, safety hazards, and increased downtime costs.
How To Handle It
Perform regular inspections, monitor performance indicators, and replace preventively based on operating hours.
Keep spare bearings on hand for critical applications to minimize downtime.
Cost & Performance Optimization ▼

What's the expected service life of 6811 bearings?

With proper installation and maintenance, 6811 bearings typically provide 20,000-50,000 hours of service life.
Why This Matters
Understanding service life helps with maintenance planning, inventory management, and cost optimization.
How To Handle It
Track operating hours, monitor performance indicators, and plan replacements based on actual service life data.
Implement condition monitoring to optimize replacement timing and avoid unexpected failures.

How can I reduce bearing maintenance costs?

Use sealed bearings for life, implement proper installation procedures, maintain clean operating environment, and use quality lubricants.
Why This Matters
Proper maintenance practices reduce total cost of ownership and prevent expensive equipment damage.
How To Handle It
Choose appropriate bearing type for environment, follow maintenance schedules, and train personnel on proper procedures.
Consider sealed bearings (6811-2RS) for applications where maintenance access is difficult.

What's the cost difference between open and sealed 6811 bearings?

Sealed bearings typically cost 20-30% more than open bearings but eliminate lubrication maintenance costs.
Why This Matters
Understanding cost implications helps make informed decisions about bearing selection and maintenance strategy.
How To Handle It
Calculate total cost of ownership including initial cost, maintenance, and downtime costs over bearing life.
For applications with difficult maintenance access, sealed bearings often provide better value despite higher initial cost.
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