Machinery's Handbook, 31st Edition
INCH KEYS AND KEYSEATS 2551 ANSI Standard Inch Series Keys and Keyseats.— American National Standard, B17.1 Keys and Keyseats, based on current industry practice, was approved in 1967, and reaf firmed in 2013. This standard establishes a uniform relationship between shaft sizes and key sizes for parallel and taper keys as shown in Table 1. Other data in this standard are given in Table 2 and Table 3 through Table 7. The sizes and tolerances shown are for single key applications only. The following definitions are given in the standard. Note: Inch dimensions converted to metric dimensions (enclosed in parentheses) are not included in the standard. Key: A demountable machinery part which, when assembled into keyseats, provides a positive means for transmitting torque between the shaft and hub. Keyseat: An axially located rectangular groove in a shaft or hub. This standard recognizes that there are two classes of stock for parallel keys used by industry. One is a close, plus toleranced key stock and the other is a broad, negative toler anced bar stock. Based on the use of two types of stock, two classes of fit are shown: Class 1: A clearance or metal-to-metal side fit obtained by using bar stock keys and key seat tolerances as given in Table 4 . This is a relatively free fit and applies only to parallel keys. Class 2: A side fit, with possible interference or clearance, obtained by using key stock and keyseat tolerances as given in Table 4 . This is a relatively tight fit. Class 3: This is an interference side fit and is not tabulated in Table 4 since the degree of interference has not been standardized. However, it is suggested that the top and bottom fit range given under Class 2 in Table 4, for parallel keys be used. Table 1. Key Size Versus Shaft Diameter ANSI/ASME B17.1-1967 (R2013) Nominal Shaft Diameter Nominal Key Size Normal Keyseat Depth Over To (Incl.) Width, W Height, H H /2 Square Rectangular Square Rectangular 5 ∕ 16 7 ∕ 16 3 ∕ 32 3 ∕ 32 … 3 ∕ 64 … 7 ∕ 16 9 ∕ 16 1 ∕ 8 1 ∕ 8 3 ∕ 32 1 ∕ 16 3 ∕ 64 9 ∕ 16 7 ∕ 8 3 ∕ 16 3 ∕ 16 1 ∕ 8 3 ∕ 32 1 ∕ 16 7 ∕ 8 1 1 ∕ 4 1 ∕ 4 1 ∕ 4 3 ∕ 16 1 ∕ 8 3 ∕ 32 1 1 ∕ 4 1 3 ∕ 8 5 ∕ 16 5 ∕ 16 1 ∕ 4 5 ∕ 32 1 ∕ 8 1 3 ∕ 8 1 3 ∕ 4 3 ∕ 8 3 ∕ 8 1 ∕ 4 3 ∕ 16 1 ∕ 8 1 3 ∕ 4 2 1 ∕ 4 1 ∕ 2 1 ∕ 2 3 ∕ 8 1 ∕ 4 3 ∕ 16 2 1 ∕ 4 2 3 ∕ 4 5 ∕ 8 5 ∕ 8 7 ∕ 16 5 ∕ 16 7 ∕ 32 2 3 ∕ 4 3 1 ∕ 4 3 ∕ 4 3 ∕ 4 1 ∕ 2 3 ∕ 8 1 ∕ 4 3 1 ∕ 4 3 3 ∕ 4 7 ∕ 8 7 ∕ 8 5 ∕ 8 7 ∕ 16 5 ∕ 16 3 3 ∕ 4 4 1 ∕ 2 1 1 3 ∕ 4 1 ∕ 2 3 ∕ 8 4 1 ∕ 2 5 1 ∕ 2 1 1 ∕ 4 1 1 ∕ 4 7 ∕ 8 5 ∕ 8 7 ∕ 16 5 1 ∕ 2 6 1 ∕ 2 1 1 ∕ 2 1 1 ∕ 2 1 3 ∕ 4 1 ∕ 2 Square Keys preferred for shaft diameters above this line; rectangular keys, below 6 1 ∕ 2 7 1 ∕ 2 1 3 ∕ 4 1 3 ∕ 4 1 1 ∕ 2 a 7 ∕ 8 3 ∕ 4 7 1 ∕ 2 9 2 2 1 1 ∕ 2 1 3 ∕ 4 9 11 2 1 ∕ 2 2 1 ∕ 2 1 3 ∕ 4 1 1 ∕ 4 7 ∕ 8 a Some key standards show 1¼ inches; preferred height is 1½ inches. All dimensions are given in inches. For larger shaft sizes, see ANSI/ASME Standard Woodruff Keys and Keyseats . Key Size versus Shaft Diameter: Shaft diameters are listed in Table 1 for identification of various key sizes and are not intended to establish shaft dimensions, tolerances or selec tions. For a stepped shaft, the size of a key is determined by the diameter of the shaft at the point of location of the key. Up through 6 1 ⁄ 2 -inch (165.1 mm) diameter shafts square keys are preferred; rectangular keys are preferred for larger shafts.
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online