Introduction to the Classification and Standards of Bearings

I. Definition and Classification of Bearing Grades

Bearing grades refer to the performance grades of bearings. They measure load capacity, deformation, and wear resistance. Bearing grades classify them into several types based on their performance and use. They are generally divided into three categories.

1. General Bearings: These are conventional bridge bearings. They bear general loads and deformations. Their grades are usually A, B, and C.

2. Heavy-duty Bearings: These are bridge bearings used to bear heavy loads and deformations, and their grades are usually I, II, and III.

3. Special Bearings: These are bearings for special applications, like earthquakes. They reduce vibrations and noise. Teachers base their grades on specific requirements.

Classification and Standards of Bearings

II. National Standard System and Industry Standard System

Bearing grade standards are mainly formulated by national and industry standards. The following are the relevant situations in the bearing industry standards:

1. National Standards: The main standards for bearing grades in China are GB/T 20672-2006 for “Highway Bridge Bearings” and JT/T 807-2015 for “Railway Bridge Bearings.”

2. Industry Standards: Besides national standards, some industry standards for bearings exist. These are TB/T 3000-2015 “Railway Bridge Bearings” and JTG/T J10-2019 “Highway Bridge Bearings.”

III. Commonly Used Bearing Standards

Bearing standards not only have grade classifications but also other classification methods. The following are commonly used bearing standards and their interpretations:

1. Classification by Bearing Material: A bearing’s material affects its quality and durability. It also impacts its service life and performance. Currently, common bearing materials include rubber, composite, metal, and hydraulic bearings.

2. Classification by Bearing Type: Different bearings suit different buildings and bridges. Standards divide them into five types: spherical, column, plate, cantilever, and direct bearings.

3. Classification by Bearing Form: Bearings come in many forms. Engineers use them in bridges and buildings of various sizes and shapes. Common forms include fixed, sliding, vibration isolation, and hinge bearings.