Bushings and Plain Bearings - Nomenclature and Numbering System

There are many different numbering systems used in the bearing industry today. The boundary dimensions for certain series of bearings are defined in various standards, such as ABMA, JIS and ISO. In addition, most manufacturers have created their own numbering systems that are a combination of the actual part, or bearing, number and a series of codes that define additional specifications.

Interchanging bearing numbers between different numbering systems requires attention to detail and full knowledge of the codes that define the specifications. AST’s Engineers and Sales Reps are experts with all numbering systems and can assist you with breaking down any bearing part number.

There are four basic types of bushings and their respective part numbers describe the characteristic features of each. For inch series, dimensions are given in 16ths of an inch while, for metric series, dimensions are given in mm. The part numbers shown below are examples given to illustrate the nomenclature for each series’ part number. Actual dimensions can be found in our bushings online catalog.

Straight Bushings

Explanation: This AST 50 straight inch series bushing (IB) has an inside diameter of 0.250” (i.e. 4/16”) and an overall length of 0.375” (i.e. 6/16”).

Flanged Bushings

Explanation: This AST 650 flanged metric series bushing has an inside diameter of 55 mm, an outside diameter of 65 mm, and an overall length of 40 mm.

Thrust Washers

Explanation: This AST 20 inch series thrust washer has an inside diameter of 1.00” (i.e. 16/16”). Thickness and outside diameter are standardized for various inside diameters.

Strip Bushings

Explanation: This AST 11 metric series strip bushing is 150 mm wide x 500 mm long (standard supply size for all strip bushings) and is 1.50 mm thick.