scope:

This standard establishes a uniform relationship between shaft size and key size for parallel and taper keys retaining similar basic sizing as found in the withdrawn B17.1-1943 standard.

This standard covers the size, type and tolerances of parallel and taper keys and keyseats, and their relationship to shaft diameters and bore diameters. The sizes and tolerances contained in this standard are intended for single key applications only.

Key strength and steel analysis entering into the makeup of stock for keys is not within the scope of this standard. Shaft diameters are listed for identification of various key sizes and are not intended to establish shaft dimensions, tolerances or selections.

This standard recognizes that there are two classes of stock for parallel keys presently used by industry. One is a broad negative toleranced bar stock and the other is a close plus toleranced keystock. Each is combined with appropriate keyseat tolerances to establish assemblies, respectively, designated as Classes 1 and 2.

Taper keys are established for Class 2 assembly only.