Seven types of tapered roller bearings (in the international standard ISO classification, the code for tapered roller bearings is the "30000" series, often referred to as "Class 7 bearings") are rolling bearings that can simultaneously withstand radial and axial forces, and are widely used in fields such as automobiles, machine tools, and construction machinery. Its working principle is based on a drag reduction mechanism that replaces sliding friction with rolling friction, while achieving joint bearing of axial and radial forces through a unique structural design. The following is a detailed analysis of its core working principle:

1. Structural composition and geometric features

Basic components: Inner ring (conical raceway): in conjunction with the shaft, the inner ring raceway is a conical surface with a cone angle usually ranging from 10 ° to 30 °.

Outer Ring (Conical raceway): In conjunction with the bearing seat, the outer ring raceway forms a conjugate conical surface with the inner ring raceway.

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Conical roller: It is in the shape of a truncated cone, with the diameter of the large end of the roller greater than that of the small end, and the generatrix of the roller is parallel to the generatrix of the raceway.

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Cage: Divided rollers to prevent them from contacting each other, usually made of stamped steel plates or engineering plastics.

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Geometric relationship: The cone tops of the inner and outer race raceways coincide with a point on the bearing axis (called the "common vertex"). This design ensures that when the roller comes into contact with the raceway, the radial force can be automatically decomposed into axial force components, achieving balanced force transmission.

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2. Working principle: Decomposition and transmission of force

Radial force bearing: When the shaft is subjected to a radial load (force perpendicular to the axis), a normal reaction force (N) is generated at the contact point between the roller and the inner and outer raceway.

. Due to the conical surface of the raceway, the normal reaction force can be decomposed into radial component force (N_r): perpendicular to the axis, directly offsetting the external radial load.

Axial force component (N_a): Parallel to the axis, it pushes the inner or outer ring to produce an axial displacement trend.

. Axial force bearing: When the shaft is subjected to an axial load (force parallel to the axis), the normal reaction force at the contact point between the roller and the raceway is also decomposed into radial and axial components. By adjusting the relative position of the inner and outer rings (such as pre tightening), the magnitude of the axial force can be controlled to balance the external axial load. Dynamic balance of force: Under the action of composite loads (radial+axial), the contact point position between the roller and the raceway is dynamically adjusted to achieve balance between the axial component of the normal reaction force and the external axial load.

This process ensures that all rollers are synchronously stressed and avoids local overload through the uniform distribution of the retaining frame.

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III. Key Design Features

Cone angle design: The cone angle (β) determines the axial load-bearing capacity of the bearing.

. The larger the cone angle, the higher the proportion of axial force, and the bearing is more suitable for bearing axial loads; Conversely, it is more suitable for radial loads. Typical cone angle range: 10 ° (high radial load) to 30 ° (high axial load), commonly used values are 15 ° to 20 °. Clearance control: Radial clearance refers to the relative displacement between the inner and outer rings in the radial direction, which affects the rigidity and operational accuracy of the bearing.

Axial clearance: The relative displacement between the inner and outer rings in the axial direction, which can be eliminated by pre tightening (applying axial force) to improve bearing rigidity.

. Pre tightening method: spring pre tightening, nut pre tightening, or hydraulic pre tightening, depending on the application scenario. Roller and raceway contact: The roller and raceway are in linear contact, with uniform distribution of contact stress and higher load-bearing capacity than ball bearings (point contact). The large end of the roller is designed with a stopper to prevent axial movement of the roller and also participate in axial force bearing.

IV. Performance Advantages and Application Scenarios

Advantages: Composite Load Bearing: Can simultaneously withstand radial and axial forces, suitable for scenarios with high axial forces (such as car differentials, machine tool spindles).

. High rigidity: Pre tightening can eliminate clearance, improve system rigidity, and reduce vibration and noise.

Alignment ability: allows for a slight deviation (usually ≤ 2 ') between the inner and outer ring axes, adapting to installation errors or shaft deformations.

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Long life: The line contact design disperses stress and, when combined with high-quality lubrication, can significantly extend the service life.

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Typical applications: in the automotive field: differentials, transmissions, wheel hub bearings, bearing the composite load of the drive shaft.

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Machine tool field: spindle, feed system, requiring high rigidity and precise positioning.

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Construction machinery: Rotary supports for excavators and cranes, capable of withstanding heavy loads and impacts.

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Wind power field: Main gearbox bearings, suitable for variable loads and harsh environments.

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