6908 Bearing 40×62×12mm

Name: 6908 Bearing 40x62x12mm - RHD Bearings
Brand: RHD Bearings
SKU: 6908

6908 BEARING SPECIFICATIONS

Precision-engineered for reliability and performance

🔍 Common Search Terms

6908 bearing specifications 40x62x12 bearing dimensions 6908 bearing load rating 6908 bearing speed limit 6908 bearing price 6908 bearing cross reference

📏Dimensions

d - ID (Bore Diameter)

40mm

D - OD (Outer Diameter)

62mm

B - Width

12mm

d₁ - Shoulder Diameter

≈47.0mm

D₂ - Recess Diameter

≈57.55mm

r₁,₂ - Chamfer Radius

min. 0.6mm

6908 Bearing: 40 × 62 × 12mm

Cross-Sectional View

⚡Load Ratings

Dynamic Load (Cr) 13.7kN

Static Load (Cor) 9.9kN

Load Capacity (kN) 13.7kN

Load Capacity (kg) 1396kg

💡What This Means

Dynamic Load (13.7kN): Maximum force while rotating. Exceeding this causes rapid wear and failure within hours.

Static Load (9.9kN): 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 8000 RPM

Oil Lubrication 12000 RPM

RHD Z2V2 Bearings 1400 RPM

RHD Z3V3 Bearings 2880 RPM

RHD Z4V4 Bearings 6000+ RPM

💡What This Means

Grease Limit (8000 RPM): Heat generation increases exponentially above this. Grease breaks down, causing seizure.

Oil Advantage (12000 RPM): Better heat dissipation allows higher speed. Required for high-speed spindles.

Safe Operating Speed: Use 90% of limit (7200 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 6908 application worldwide

📊Vibration Classes

V2 Grade

Low: 180 μm/s

Med: 150 μm/s

High: 130 μm/s

V3 Grade

Low: 110 μm/s

Med: 90 μm/s

High: 80 μm/s

V4 Grade

Low: 82 μm/s

Med: 50 μm/s

High: 50 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 < 46 dB

Z3 Grade < 42 dB

Z4 Grade (Quiet) < 42 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) 1-11 μm

C0 (Normal) 6-20 μm

C3 (Loose) 15-33 μm

C4 (High Temp) 28-46 μm

C5 (Extra High Temp) 40-64 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

6908-ZZ

When to Use 6908-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

6908-2RS

Protected

Double rubber seals

Speed Factor: 0.7 (5600 RPM)

Protection: Moisture and dust

Lubrication: Sealed for life

When to Use 6908-2RS

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

6908

High Speed

Open bearing, no seals

Speed Factor: 1.0 (8000 RPM)

Protection: None

Lubrication: External required

6908-Z

Balanced

Single metal shield

Speed Factor: 0.95 (7600 RPM)

Protection: Light dust protection

Lubrication: Pre-greased

6908-RS

Protected

Single rubber seal

Speed Factor: 0.8 (6400 RPM)

Protection: Moisture and dust

Lubrication: Pre-greased, sealed

APPLICATIONS

Precision performance across industries

Gearbox Shafts

Automotive transmission shafts
Industrial gear reducers
Crane gearbox drives
Mining haul truck shafts
Heavy machinery gearboxes
Agricultural equipment gears
Elevator drive arms
Construction equipment shafts

Key Requirements: 40mm shaft with 13.70kN (≈1396kg) dynamic load capacity, 8,000 RPM grease lubrication, 62×12mm profile for gearboxes

Robotic Arms

Industrial robot elbows
Automated welding arms
Manufacturing robot wrists
Medical robot pivots
Assembly line robot arms
Inspection robot mountings
Material handling pivots
CNC arm rotation joints

Key Requirements: Precision 40mm bore with 9.90kN (≈1010kg) static load

Heavy Drives

Pump motor drives
Conveyor main shafts
Agricultural machinery spindles
Industrial mixer drives
Packaging machine drives
Mining conveyor rollers
Material handling shafts
Hydraulic motor drives

Key Requirements: 40mm bore, 12mm width for heavy load drives

Compatible Models & Shaft Requirements

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

🔄Related Models

🔧Shaft Requirements

Nominal Diameter 40.000mm

Tolerance Grade h6 (39.984-40.000mm)

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 40mm bore (ID) with 6808, 6008, 16008, so it can be considered where the shaft is fixed at 40mm. The 6908 is rated 13.70kN dynamic / 9.90kN static at 62mm OD — more capacity than the 6808 (5.10kN) and less than the heavier-duty 6008 (17.00kN).

💰Value Engineering

Best value in small-bearing category for 13.70kN performance. Quality bearings last 3-10x longer than cheap alternatives, reducing total cost of ownership.

FREQUENTLY ASKED QUESTIONS

Expert guidance for 6908 bearing applications

Bearing Selection & Replacement ▼

What makes the 6908 bearing suitable for high-speed applications?

The 6908 bearing is designed for high-speed applications with a grease RPM rating of 8,000 and oil RPM of 12,000, making it ideal for precision machinery and high-speed equipment.

Why This Matters

High-speed capability ensures reliable performance in demanding applications without premature failure or excessive heat generation.

How To Handle It

Select 6908 bearing for applications requiring speeds up to 8,000 RPM with proper lubrication and mounting practices.

For maximum speed performance, use oil lubrication and ensure proper shaft and housing tolerances (h6 shaft tolerance recommended).

Can I replace a 6908 bearing with other series bearings?

The 6908 bearing can be cross-referenced with 6008, 6208, 6308, and 6808 series bearings that share the same 40mm bore diameter, though load capacities and dimensions may vary.

Why This Matters

Proper cross-referencing ensures compatibility while allowing flexibility in bearing selection based on specific application requirements.

How To Handle It

Verify outer diameter (62mm) and width (12mm) compatibility before replacement, and consider load requirements when selecting alternatives.

Always check the specific application requirements and consult technical specifications before making cross-series replacements.

What is the load capacity of the 6908 bearing?

The 6908 bearing has a dynamic load rating of 1397.4kg (13.70kN) (1397kg) and static load rating of 9.90kN (1010kg), making it suitable for moderate to high-load applications.

Why This Matters

Understanding load capacity is crucial for proper bearing selection and preventing premature failure due to overloading.

How To Handle It

Calculate your application's equivalent dynamic load and ensure it doesn't exceed 1397.4kg (13.70kN) for optimal bearing life.

For applications with high static loads, ensure the static load rating of 1009.8kg (9.90kN) is not exceeded to prevent permanent deformation.

Installation & Maintenance ▼

What shaft tolerance is recommended for the 6908 bearing?

The 6908 bearing requires an h6 shaft tolerance with a nominal diameter of 40.000mm and tolerance range of 39.987-40.013mm for optimal performance.

Why This Matters

Proper shaft tolerance ensures correct fit and prevents issues like excessive clearance or interference that can lead to premature failure.

How To Handle It

Machine the shaft to h6 tolerance (39.987-40.013mm) with a surface finish of Ra 0.8μm maximum and runout tolerance of 0.013mm maximum.

Use precision measuring tools to verify shaft dimensions before installation, as even small deviations can significantly impact bearing performance.

How should I lubricate the 6908 bearing?

The 6908 bearing can be lubricated with grease (up to 8,000 RPM) or oil (up to 12,000 RPM), with the choice depending on speed requirements and application conditions.

Why This Matters

Proper lubrication is essential for bearing performance, reducing friction, preventing wear, and extending service life.

How To Handle It

For high-speed applications, use oil lubrication. For general applications, use high-quality bearing grease with appropriate viscosity.

Avoid over-lubrication as it can cause excessive heat generation and reduce bearing efficiency, especially in high-speed applications.

What is the recommended installation method for the 6908 bearing?

The 6908 bearing should be installed using proper bearing installation tools, ensuring even pressure distribution and avoiding damage to the bearing components.

Why This Matters

Proper installation prevents bearing damage, ensures correct fit, and maximizes service life while maintaining performance characteristics.

How To Handle It

Use bearing installation tools or sleeves to apply pressure evenly on the inner ring, never apply force directly to the outer ring or balls.

Heat the bearing to 80-100°C before installation to expand the inner ring, making installation easier and reducing the risk of damage.

Troubleshooting ▼

Why is my 6908 bearing running hot?

A hot-running 6908 bearing is typically caused by over-lubrication, excessive load, misalignment, or insufficient clearance, requiring immediate investigation and correction.

Why This Matters

Excessive heat can lead to premature bearing failure, lubricant breakdown, and potential damage to surrounding components.

How To Handle It

Check lubrication levels, verify load conditions, inspect for misalignment, and ensure proper clearance. Reduce speed if necessary and monitor temperature.

Use infrared thermometers to monitor bearing temperature during operation - temperatures above 80°C indicate potential problems requiring attention.

What causes excessive noise in the 6908 bearing?

Excessive noise in the 6908 bearing is usually caused by contamination, insufficient lubrication, bearing damage, or improper installation, each requiring specific corrective actions.

Why This Matters

Unusual noise often indicates bearing problems that, if left unaddressed, can lead to catastrophic failure and equipment damage.

How To Handle It

Inspect for contamination, check lubrication levels, examine bearing surfaces for damage, and verify proper installation and alignment.

Use vibration analysis tools to detect bearing problems early, as noise often precedes visible damage and can be caught before failure occurs.

How do I identify if my 6908 bearing needs replacement?

Signs that your 6908 bearing needs replacement include excessive noise, vibration, heat generation, increased friction, or visible damage to bearing components.

Why This Matters

Timely bearing replacement prevents catastrophic failure, reduces downtime, and protects other equipment components from damage.

How To Handle It

Monitor bearing performance regularly, conduct vibration analysis, and inspect for visual signs of wear or damage during maintenance intervals.

Establish a preventive maintenance schedule based on operating conditions - high-speed applications may require more frequent inspection and replacement.

Cost & Performance ▼

What is the cost-benefit of choosing the 6908 bearing over alternatives?

The 6908 bearing offers excellent value with 1397.4kg (13.70kN) load capacity in a compact 40x62x12mm design, providing 3-10x longer service life than cheap alternatives.

Why This Matters

Quality bearings reduce total cost of ownership through longer service life, reduced maintenance, and fewer unplanned failures.

How To Handle It

Calculate total cost of ownership including initial cost, maintenance, and downtime costs when comparing bearing options.

Consider the cost of equipment downtime and replacement labor when evaluating bearing options - quality bearings often pay for themselves through reduced maintenance costs.

How can I optimize the performance of my 6908 bearing?

Optimize 6908 bearing performance by ensuring proper installation, correct lubrication, appropriate load conditions, and regular maintenance according to manufacturer specifications.

Why This Matters

Optimized performance extends bearing life, reduces maintenance costs, and ensures reliable operation in demanding applications.

How To Handle It

Follow manufacturer guidelines for installation, use recommended lubricants, monitor operating conditions, and establish regular maintenance schedules.

Implement condition monitoring systems to track bearing performance and identify optimization opportunities before problems occur.

What factors affect the service life of the 6908 bearing?

The service life of the 6908 bearing is affected by load conditions, speed, lubrication quality, operating temperature, contamination levels, and installation practices.

Why This Matters

Understanding factors that affect service life helps optimize operating conditions and maximize bearing performance and longevity.

How To Handle It

Control operating conditions within recommended limits, maintain proper lubrication, prevent contamination, and ensure correct installation and alignment.

Keep detailed records of operating conditions and maintenance activities to identify patterns and optimize bearing service life over time.

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