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Self-Aligning Ball Bearings.jpg
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China Self-Aligning Ball Bearings Factory - High-Quality Suppliers for Radial Load Solutions

Self-aligning ball bearings are a type of double-row bearing widely used in various applications. With an outer ring featuring a spherical raceway surface that is concentric with the bearing's central point, these bearings offer unique self-aligning capabilities. The inner ring is designed with two rows of raceways, allowing the balls and cage to tilt freely during operation. This feature enables the bearing to automatically adjust for misalignment, which can result from shaft deflection or errors in machining and installing the shaft and housing. It is essential to note that the maximum permissible relative tilt between the inner and outer rings should not exceed 3 degrees for optimal performance, Manufactured in China, these self-aligning ball bearings are primarily intended for carrying radial loads, but they can also accommodate minor axial loads in conjunction with radial loads. However, they are not suitable for supporting pure axial loads. As a trusted factory and supplier, we ensure high-quality products that meet the needs of various industries
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    Product Details

    Self-aligning ball bearings are available in two main types

    • ⚙️ Basic design bearings
    • 🔒 Bearings with rubber seals on both sides

    Basic Design

    The basic design bearings are available with either cylindrical bore or tapered bore (taper ratio 1:12). Self-aligning ball bearings with a tapered bore can be directly mounted on tapered shaft diameters using a locking nut. Alternatively, they can be easily installed on cylindrical shafts using appropriate adapter sleeves or withdrawal sleeves. The radial clearance of the bearing can also be adjusted using an adapter sleeve.

    The internal design of the basic self-aligning ball bearings has been improved, providing higher load-carrying capacity compared to the original standard design. As a result, these bearings offer broader applicability—either enabling the same-sized bearing to carry heavier loads or, under unchanged load conditions, improving operational reliability and extending service life.

    Sealed Bearings

    Self-aligning ball bearings can be equipped with contact seals on both sides, such as 2RS or 2RS1 type seals. These seals are made of wear-resistant synthetic rubber reinforced with thin steel plates. The bearings are permanently lubricated and require no maintenance. They should not be heated or cleaned before installation.

    Dimensions

    The basic dimensions of self-aligning ball bearings comply with ISO 15:1981 and are listed in the dimension tables.

    Angular Misalignment

    Self-aligning ball bearings are designed to accommodate angular misalignment between the inner and outer rings.

    The maximum allowable angular misalignment under normal operating conditions is provided in the table below. Whether the maximum value can be utilized depends on the bearing configuration design and the type of seals used.

    Self-aligning ball bearings are manufactured with standard (normal) tolerance grades. Precision grades such as P6 and P5 are also available. Tolerance grades can be referenced in the corresponding tables.

    Radial Internal Clearance

    Standard self-aligning ball bearings are supplied with normal radial internal clearance. Bearings with a tapered bore are supplied with C3 group clearance as standard. Bearings with internal clearance greater or smaller than the standard value can be produced according to customer requirements. Radial clearance values can be found in the clearance tables.

    Cages

    The standard cage for self-aligning ball bearings is made of glass fiber-reinforced nylon 66. This material offers advantages such as good processability, light weight, and self-lubricating properties. It can accommodate higher operating speeds and withstand temperatures up to +120°C.

    For bearings operating continuously under high temperatures or harsh conditions, stamped steel cages or machined brass cages are available. For non-standard cage requirements, please contact the technical department.

    Minimum Load

    To ensure satisfactory operation of ball and roller bearings, a certain minimum load must be applied. This requirement also applies to self-aligning ball bearings. Otherwise, at high speeds, inertial forces acting on the balls and cage, along with friction from the lubricant, may adversely affect rolling behavior, causing destructive sliding between the balls and raceways.

    The minimum required load can be estimated using the following formula:

    Frm = kr · ( γ · n / 1000 )2/3 · dm3.3
    📌 Where:
    • Frm — Minimum radial load (N)
    • kr — Minimum load coefficient
      = 40 for series 12 and 13 bearings
      = 45 for series 22 bearings
      = 50 for series 23 bearings
    • γ — Operating viscosity of the lubricant at operating temperature (mm²/s)
    • n — Rotational speed (r/min)
    • dm — Bearing mean diameter = 0.5(d + D) (mm)

    The weight of the supported components plus external forces often exceeds the minimum load. If not, additional loads must be applied, such as increasing belt tension or using other similar methods.

    ⚡ Dynamic Equivalent Bearing Load
    P = Fr + Y1 · Fa    (kN)   when Fa / Fr ≤ e
    P = 0.65Fr + Y2 · Fa    (kN)   when Fa / Fr > e

    Values for Y1, Y2, and e are listed in the bearing dimension tables.

    🔷 Static Equivalent Bearing Load
    P = Fr + Y0 · Fa    (kN)

    The value of Y0 is provided in the bearing dimension tables.

    ❓ Frequently Asked Questions
    Q What are the two main types of self-aligning ball bearings?
    Self-aligning ball bearings come in two main types: basic design bearings (available with cylindrical or tapered bore) and bearings with rubber contact seals on both sides (such as 2RS or 2RS1 type), which are permanently lubricated and maintenance-free.
    Q What is the difference between cylindrical bore and tapered bore self-aligning ball bearings?
    Cylindrical bore bearings are standard and mounted directly on cylindrical shafts. Tapered bore bearings (taper ratio 1:12) can be mounted directly on tapered shafts using a locking nut, or on cylindrical shafts using adapter sleeves or withdrawal sleeves, allowing easy radial clearance adjustment.
    Q What cage materials are available for self-aligning ball bearings?
    The standard cage material is glass fiber-reinforced nylon 66, which offers light weight, self-lubrication, and temperature resistance up to +120°C. For high-temperature or harsh operating environments, stamped steel cages or machined brass cages are also available upon request.
    Q What radial internal clearance is standard for self-aligning ball bearings?
    Standard self-aligning ball bearings are supplied with normal radial internal clearance. Bearings with a tapered bore are supplied with C3 group clearance as the default. Custom clearance values—greater or smaller than standard—can be produced to meet specific customer requirements.
    Q Why is a minimum load required for self-aligning ball bearings?
    A minimum load is necessary to prevent destructive sliding between the balls and raceways. At high speeds, insufficient load allows inertial forces on balls and cage—combined with lubricant friction—to disrupt proper rolling motion. If external forces do not meet the minimum load requirement, additional preload (e.g., increased belt tension) should be applied.
    Q How is the dynamic equivalent bearing load calculated for self-aligning ball bearings?
    The dynamic equivalent load depends on the ratio of axial to radial load (Fa/Fr) relative to the factor e. When Fa/Fr ≤ e, use P = Fr + Y1·Fa. When Fa/Fr > e, use P = 0.65Fr + Y2·Fa. The coefficients Y1, Y2, and e are listed in the bearing dimension tables.