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68 Series
Home Deep Groove Ball Bearings 68 Series

6808-2RS Thin Section Deep Groove Ball Bearing For Robotics & Lightweight Assemblies | 40×52×7 mm

6808-2RS Thin Section Deep Groove Ball Bearing For Robotics & Lightweight Assemblies | 40×52×7 mm

The 6808-2RS is a single-row thin-section deep groove ball bearing from the 6800 series, fully sealed on both sides with contact rubber lips that ride directly against the inner ring shoulder. Featuring a 40 mm bore and a highly compact 52 mm outer diameter, it offers an exceptionally slim 7 mm cross-section. This geometry delivers essential weight reduction and space savings without sacrificing the contamination exclusion and long-term grease retention of a fully sealed unit. This combination—a large 40 mm bore within a narrow 52 mm envelope, integrated contact seals, and life-time lubrication—makes the 6808-2RS the optimal solution for precision machinery operating in dusty, damp, or debris-prone environments where standard-sized bearings would be too bulky or heavy.

6808-2RS Deep Groove Ball Bearing 40×52×7 mm | 68 Series | Contact Rubber Seals (2RS)

Engineered for lightweight mechanisms that require strict contamination control but cannot accommodate regular re-lubrication, the 6808-2RS integrates two resilient rubber seals onto a 40 mm bore platform. This sealing configuration establishes a physical barrier that reliably locks out fine particulates, moisture, and operational debris while trapping the factory grease charge inside the raceway for the entirety of the bearing's lifespan. It shares the exact 40 × 52 × 7 mm dimensions as the shielded 6808-ZZ and the open 6808, allowing it to seamlessly upgrade any housing machined for those types without modification. While the 6808-ZZ permits slightly higher rotational speeds due to its low-friction steel shields, the 6808-2RS trades a fraction of that speed capability for vastly superior environmental protection—a necessary compromise for applications subjected to outdoor conditions or industrial contaminants.

6808-2RS Thin Section Deep Groove Ball Bearing For Robotics & Lightweight Assemblies | 40×52×7 mm

Comprehensive Applications

The 6808-2RS is universally selected when a 40 mm shaft requires reliable, maintenance-free rotation within heavily constrained radial and axial dimensions:

Bicycles & Light Electric Vehicles (LEVs)
  • High-end mountain bike and E-bike bottom brackets
  • Oversized wheel hubs for low-friction, weather-sealed rolling
  • Electric scooter drive wheel supports and steering headsets
  • Suspension pivot points requiring high load capacity in narrow spaces
Robotics & Motion Control
  • Robotic arm joint articulations and harmonic drive assemblies
  • Hollow-shaft stepper motors and precision servo actuators
  • Automated Guided Vehicle (AGV) drive and steering pivot points
  • Exoskeleton and wearable robotic mobility joints
Drones & Aerospace Camera Systems
  • Large payload UAV gimbal mounts and camera stabilization rigs
  • Lightweight aerospace actuator pivot points
  • Radar antenna azimuth positioning assemblies
  • Airborne optical and LIDAR sensor rotational platforms
Medical Imaging & Optical Equipment
  • CT scanner and MRI machine lightweight rotational components
  • Ophthalmic diagnostic instrument adjustment mechanisms
  • Surgical robot positioning arms needing sterile environment protection
  • Precision optical telescope and tracking mounts

Key Performance Features

01. Ultra-Thin 6800-Series Profile for Maximum Space Efficiency

Sharing the identical 40 mm bore, 52 mm OD, and 7 mm width of the open 6808 and shielded 6808-ZZ, this bearing is a direct drop-in replacement. The true value of the 6800 thin-section series lies in its exceptional bore-to-OD ratio. For engineers looking to increase shaft diameter to improve torsional stiffness—without ballooning the overall size or weight of the machine—the 6808-2RS provides that structural rigidity alongside robust environmental sealing. Upgrading from an open bearing to this sealed version requires zero changes to your existing housing blueprints.

02. Factory-Sealed Lubrication for Zero-Maintenance Longevity

By utilizing twin contact seals, this bearing not only blocks external contaminants but also rigorously retains its original grease fill under varying operational loads. In enclosed robotic joints or sealed E-bike hubs, manual re-lubrication is often physically impossible. The 6808-2RS anticipates this by arriving pre-packed with premium grease engineered for its specific temperature and speed profile. This ensures consistent performance from initial assembly to eventual replacement, entirely eliminating the need for complex lubrication channels in the surrounding housing.

03. Resilient Rubber Seals on a Large 40 mm Shaft

Protecting a 40 mm shaft diameter from contamination is inherently more challenging than sealing a miniature bearing due to the much larger sealing circumference. The 6808-2RS tackles this by deploying premium, oil-resistant synthetic rubber lips bonded to steel inserts. These lips maintain constant, even pressure against the inner ring shoulder. This self-contained defense mechanism is vital in environments where the housing itself cannot be trusted to deflect dust, water splash, or grit.

Technical Specifications

Bearing Type Single Row Deep Groove Ball Bearing
ISO Dimension Series 6800 Series (Thin Section)
Basic Designation 6808
Suffix Double Contact Rubber Seal (2RS)
Bore Diameter (d) 40 mm
Outer Diameter (D) 52 mm
Width (B) 7 mm
Material (Races & Balls) High-Carbon Chrome Steel (GCr15 / SAE 52100)
Precision Class ISO Class 6 (ABEC-3) / Class 5 (ABEC-5) Available
Cage Design Pressed Steel
Dynamic Load Rating (Cʳ) ~5.10 kN
Static Load Rating (C₀ʳ) ~4.40 kN
Limiting Speed (Grease) ~6,700 r/min
Limiting Speed (Oil) N/A — permanently sealed
Weight (approx.) 0.033 kg

Interchange Part Numbers

The 6808-2RS is globally recognized and cross-referenced under various nomenclature conventions by leading manufacturers (Note: SKF frequently uses the 618xx designation for this series):

  • SKF: 61808-2RS1
  • NSK: 6808DD / 6808DDU
  • FAG (Schaeffler): 61808-2RSR
  • NTN: 6808LLU / 6808LLB
  • KOYO: 6808-2RS
  • NACHI: 6808-2NSE
  • Generic: 6808-2RS, 61808-2RS, 6808DDU, 6808UU, 6808VV, 6808EE

Design & Configuration

Operating on the Conrad assembly principle, the 6808-2RS is a single-row radial ball bearing optimized for the thin-walled 6800 series dimensional standard. Despite its slim 7 mm profile, the meticulously engineered raceway geometry and ball complement generate a dynamic load rating of approximately 5.10 kN and a static rating of 4.40 kN—delivering substantial load-carrying capacity for a bearing weighing merely 33 grams. While the contact seals induce a slight frictional torque increase compared to the metal-shielded 6808-ZZ, bringing the grease limiting speed to roughly 6,700 r/min, this trade-off is highly advantageous for most industrial applications. If an assembly demands speeds significantly exceeding 7,000 r/min in a perfectly clean setting, the 6808-ZZ is the appropriate alternative. However, for moderate speeds where the equipment faces dust, humidity, or outdoor debris, the 6808-2RS is technically superior. Available in precision grades up to ABEC 5 (P5), it easily meets strict runout requirements for sensitive motion control systems.

"When the design demands a large 40 mm shaft but restricts radial space to a mere 52 mm, the 6808-2RS thin-section sealed bearing solves the engineering puzzle. Providing a standard 6800-series footprint, self-contained lifelong lubrication, and aggressive contamination exclusion, it acts as a maintenance-free, drop-in solution for robotics, E-bikes, medical scanners, and aerospace mechanisms where saving weight and blocking debris are equally critical."

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Details
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Details

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