Two types of bearings are used to support a shaft, i.e., sliding and rolling bearings. With small friction, high rotation flexibility and easy to maintain, rolling bearings are widely used standard components of mechanical equipment. This chapter illustrates their codes, specified and simplified representation. 


 Structureof rolling bearings(滚动轴承的结构)

The structure of rolling bearings consists of four components, shown in Fig. 7-47.

(1) Inner race   Tightly mounted on the shaft and rotating with it.

(2) Outer race   Mounted on the bearing's bracket hole and fastened.

(3) Rolling elements   Located between the inner and outer rings. They include balls, columns, and cones.

(4) Cage   Used to isolate the rolling element.


(1)内圈   紧密套装在轴上,随轴转;

(2)外圈   装在轴承座的孔内,固定不动;

(3)滚动体   形式有圆球、圆柱、圆锥等,排列在内、外圈之间;

(4)保持架   用来把滚动体隔开。

Types of rolling bearings(滚动轴承的分类)

(1) Radialbearing   Used to bear the radial load. See deep groove ball bearingsin Fig.7-47a.

(2) Thrust bearing   It only bears the axial load. See thrust bearings in Fig.7-47b.

(3) Radial thrust bearing  It bears both the radial and axial loads. See the tapered roller bearing in Fig. 7-47c.

(1)向心轴承  主要用于承受径向载荷,如图7-47a中的深沟球轴承。

(2)推力轴承  只承受轴向载荷,如图7-47 b中的推力球轴承。

(3)向心推力轴承   能同时承受径向载荷和轴向载荷,如图7-47 c中的圆锥滚子轴承。

 Rolling bearing codes(GB/T 272—1993)(滚动轴承的代号)

According to national standards, structure, dimension,tolerance degree and technical requirements are represented by the codes of the rolling bearing.Codes are composed of pre-code, base code, and post-code. These quence is the following:

 Pre-code   Base code   Post-code

The base code is essential. The pre-code and post-code are supplementary codes and are added before and after the base code, respectively, when the structure, dimension, tolerance and techn ical requirements of the bearing change.If necessary, consult the relevant national standard. 


Some common basic codes arelisted below. The basic code consists of the bearing type code, dimension series code and inner diameter code (The dimension series code consists of width or height series). Code meanings are explained below:


Example 1  Bearing6206    (例1 轴承6206)

Rolling bearing marks should include the name, its code and the national standard number. The mark symbol of the above-mentioned deep groove ball bearing is the following: 

滚动轴承的标记内容:名称、 代号和国标号,所以上述深沟球轴承的规定标记为:

Roll bearing 6206  GB/T 276—1994       滚动轴承6206   GB/T 276—1994

Example 2  Bearing51210   (例2  轴承51210)

Specifiedsymbol: Rollingbearing 51210   GB/T 301—1995

The last two digits represent a 2-digit number of the inside diameter of the bearing. Multiply the number from 04 by 5, the result of which is the inside diameter of the bearing. Therefore, the inside diameter of the bearing is d=10×5=50mm.

规定标记为:滚动轴承51210   GB/T  301—1995


If the 2-digit number representing the inside diameter is below “04”, the standard specifies:


00 represents d=10mm,      00表示d=10mm;

01 represents d=12mm,      01表示d=12mm;

02 represents d=15mm,      02表示d=15mm;

03 represents d=17mm.      03表示d=17mm

Representation of rollingbearings(GB/T 4459.7—1998)(滚动轴承的画法)

There is no need to draw the part drawing for rolling bearing as it is a standard component. Therefore the specified representation and simplified representation that are specified by national standard can be used to represent the rolling bearing in the assembly drawing. In the drawing, the main dimensions of the bearing should be referenced from the national standards according to corresponding bearing code in terms of the external diameter D, inner diameter d, and width B. And then use these main dimensions as references, draw the dimensions of rest parts with the proportion of the main dimensions. The specified and simplified representations of rolling bearings are shown in Table 7-8. 


If the primary structure of the rolling bearing needs to be represented in a more detailed way, a specified representation can be adopted when drawing the assembly. If the primary structure of the rolling bearing needs to be represented in a simple way, the simplified representation, namely, the feature representation (table 7-8) or conventional representation (shown in Fig. 7-48) can be used.