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Smooth Self-Aligning Ball Bearings from China - Top Suppliers and Reliable Factory Options

Self-aligning ball bearings are a type of double-row bearing crafted to enhance performance and reliability. Manufactured in China, these bearings feature an outer ring with a spherical raceway surface that is concentric with the center point of the bearing. The inner ring is designed with two rows of raceways, allowing the balls and cage to tilt freely during operation. This self-aligning capability effectively compensates for misalignment resulting from shaft deflection or errors in machining and installation of 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, These high-quality self-aligning ball bearings are primarily engineered to handle radial loads, making them ideal for various industrial applications. Additionally, they can accommodate minor axial loads alongside radial loads, although they are not suitable for pure axial loads. As a trusted factory and supplier, we ensure our self-aligning ball bearings meet stringent industry standards, providing reliable solutions for your engineering needs

Product Details

Self-Aligning Ball Bearings — Available Types

① Basic Design Bearings
② 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.

▶ Improved Internal Design: 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.

▶ Tolerances: 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.

▶ High-Temperature / Harsh Conditions: 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:

F_rm = k_r · ( γ · n / 1000 )^2/3 · d_m^3.3

Where:

F_rm — Minimum radial load (N)
k_r — 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)
d_m — 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 = F_r + Y₁ · F_a (kN) when F_a / F_r ≤ e

· P = 0.65 F_r + Y₂ · F_a (kN) when F_a / F_r > e

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

Static Equivalent Bearing Load

P = F_r + Y₀ · F_a (kN)

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

Frequently Asked Questions (FAQ)

Q What are the two main types of self-aligning ball bearings?

Self-aligning ball bearings are available in two main types: basic design bearings (with either 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 Can self-aligning ball bearings be mounted on cylindrical shafts?

Yes. Bearings with a tapered bore can be mounted on cylindrical shafts using adapter sleeves or withdrawal sleeves. These sleeves also allow adjustment of the radial internal clearance of the bearing during installation.

Q What is the standard cage material for self-aligning ball bearings?

The standard cage is made of glass fiber-reinforced nylon 66, which is lightweight, self-lubricating, and capable of withstanding temperatures up to +120°C. For high-temperature or harsh operating environments, stamped steel cages or machined brass cages are available as alternatives.

Q Why is a minimum load required for self-aligning ball bearings?

At high speeds, if insufficient load is applied, inertial forces on the balls and cage — combined with lubricant friction — can cause destructive sliding between the balls and raceways. A minimum radial load must always be maintained to ensure proper rolling contact and prevent premature bearing damage.

Q What radial internal clearance is standard for self-aligning ball bearings with a tapered bore?

Self-aligning ball bearings with a tapered bore are supplied with C3 group clearance as standard. Bearings with cylindrical bores are supplied with normal clearance. Custom clearance values — greater or smaller than standard — can be produced upon customer request.

Q Are precision tolerance grades available for self-aligning ball bearings?

Yes. While self-aligning ball bearings are manufactured in standard (normal) tolerance grades by default, precision grades such as P6 and P5 are also available for applications requiring higher accuracy. Detailed tolerance specifications can be found in the corresponding tolerance tables.